Introduction and Acknowledgements

Good grief. This was hard to write. It hasn’t been proofed and contains some errors (as well as allusions to sections that were never written). I take some solace in the knowledge that even if the reader despises the text, he or she can at least enjoy the pictures. Some parts are missing. I lost my canopy map and didn’t include a complete species list.
I’d like to acknowledge some people here. First, the other students in the group. Frankly, I used some of their pictures (but only when my pictures of the same animal were slightly-out-of-focus—there’s integrity and then there’s myopia). The staff at GIAS and Tiputini were very helpful. We didn’t go anywhere on this journey were hotel reservations or transportation wasn’t waiting for us. I’d especially like to thank Dr. Mackie. During our journeys through the rainforest and the Galapagos archipelago Dr. Mackie assumed many nick-names (the most prominent were “Big Mack” and “Mack Attack”). These monikers were applied lovingly. Dr. Mackie’s enthusiasm for wildlife and his desire that we make the most of our journey ensured we missed no opportunity to add depth and perspective to the multifarious life forms we encountered throughout Ecuador. Moreover, he granted me an extension when I was unable to finish this report by deadline, making the quality of this entire report considerably greater.
I didn’t write about many things that were just-as-worthy of comment as the things I did study. For instance, the time spent on lemon ants and lava lizards compared to blue footed boobies or giant tortoises does not reflect their relative worth. There are some extremely interesting observations I’d like to write about, but I’m all spent.
This journey was very nearly perfect. The only significant change I’d make would be to include a journey to Isabela Island. I’m very tired and past my extended deadline, so I’ll finish with this: I can guarantee you’ll enjoy reading this report more than I enjoyed writing it. I only hope you like it considerably more. I think you will.

May 24
The City of Quito The city of Quito literally leaves one breathless. At 2800 meters (~9200 ft.) above sea level, nestled on the eastern slopes of the still-active Pichincha volcano, the air is much thinner than in Chicago (at a paltry 179 meters). The effect is dizzying. Five flights of stairs feels like fifteen. Head-aches are common.
Our orientation was short, on account of the cancellation of our original flight due to storms over Houston. We arrived surreptitiously on Thursday, May 24 for Ecuadorian Independence Day. Like all Latin American countries (excluding only Brazil), Ecuador began as a Spanish colony. The first public calls for revolution in Latin America occurred in Quito on August 10, 1809. While May 24 is the date that Ecuador and Colombia became an independent republic (The Republic of Gran Colombia) most of the celebration occurs on the August holiday. Thus, the festivity we saw was underwhelming: a small band, no dancing, and lots of indifference.
We started our tour at the Virgin of Quito, an enormous statue of the Virgin Mary overlooking the city. A full 95% of the population in Ecuador is Roman Catholic (though one suspects the indigenous population must be under sampled). While on a balcony at the top of the Virgin, a group of school children walked by and said “Hola Estados Unidos!” (literally: “Hello United Americans!”). In the United States, we use “American” as a short-hand name for our own country, quite divorced from its literal geographical meaning. In Europe, similarly, “America” means only the United States. However, the inhabitants of South and Central America consider themselves very much American. Thus, in Colombia we are “norteamericanos” and most everywhere else “gringos”. Simply stated, the people from the United States lack a succinct national adjective in Latin America. Unfortunately, I see no hope for a solution.
After inspecting the Virgin, we visited a Fransican Church with a connecting monastery/museum. The Fransicans worship Mary, the official head of their order. Thus, in the choir room they built her a throne amongst the more humble seats of the order’s monks. If Jesus shows up, he will have to stand. The choir room overlooks the main church and houses an off-limits organ, collecting dust in the corner. The organ can never be played on account of the construction of the ceiling, which is made of decorative wooden tiles held together by nothing but pressure. Unlike a true vaulted ceiling, which maintains its form by gravity’s compression of the structural materials, the wooden tiles are neither stable nor load bearing. The organ was off-limits and the church goers protected by a recently added safety-ceiling. The vibrations can dislodge the tiles, causing a domino effect. Church goers were recently killed by falling tiles.
Inside the choir room itself we saw a device for turning the large, framed pages of lyrics so all the monks could see them. One unfortunate monk has to enter the base of the rotating pages through a tiny door and spin a wheel inside. Our guide revealed that he had once gone inside the little door. He then shook nervously and changed the subject.
Another interesting oddity was the “secret-box”. Senior members of the order were sometimes privy to sensitive information. They kept this information in a box with a series of drawers. For instance, a box might have one drawer for keeping things in, and then six additional drawers. The storage drawer can only be unlocked if the six other doors are opened in the correct sequence. Thus, the number of possible combinations per box equals the factorial of the number of non-storage drawers (for six drawers, 6!=6∙5∙4∙3∙2∙1=720 combinations). Only two people could know the combination for the secret-box: the box-maker and the senior monk. Of course, two people can only keep a secret if one of them is dead, so the monks typically had the box-maker killed.
While touring the monastery, we saw a secret box with 50 non-storage drawers (resulting in a number of possible combinations approaching the number of atoms in the entire universe). I thought briefly about a mischievous monk, dying to know what’s inside the secret-box, conspiring to try every combination on an 8 non-storage drawer box (40,320 combinations). At ten-permutations a day (he has to be stealthy after all) he could work no longer than 11 years before finding the correct combination. I imagine this monk, opening the special drawer, finds a hand-written letter congratulating him on his patience and systematic methodology. Of course, it would seem to be an exercise in futility to build a drawer with as many as 50 drawers (with a massive 3 with sixty-four zeros combinations). Anyone who would pilfer its contents could simply take an axe to it, rather than spend the eons of requisite time trying to find the proper sequence.
Inside the monastery, a dome-shaped acoustic ceiling was constructed to allow priests and monks to talk at a safe distance of six meters. The idea is similar to a set of tin cans connected by a string. The string acts as a conduit for the vibrations, carrying them from one can to another. Similarly, by talking into the wall, the ceiling picks up the vibrations and carries them to the opposite wall. The effect of having a conversation through the ceiling was eerily like having a voice in my head. These little oddities are really fascinating, inasmuch as they are ingenious solutions to the arbitrary demands of the order.
Our tour included an exposition of 16th and 18th century dolls. When the Spaniards arrived in Ecuador with Catholicism in tow, they came up against a language barrier. The indigenous peoples spoke Quechua. Art became an instrumental tool in successful conversion of the native peoples. These dolls vary minutely based on whether they were made by Quitian or Spanish artists. While I couldn’t reliably tell them apart, our guide spent considerable time convincing the group of the essential dichotomy of styles—often quizzing us on new specimens. As I inspected the dolls, which include haloed saints, apostles, pontiffs and the holy mother, I imagined a native Quitian trying to make sense of it all. Is there even the slightest chance the natives imagined Catholicism to be monotheistic?
After leaving the monastery we took a bus to the University of San Francisco de Quito (USFQ). USFQ has about 2,000 students, but a larger number of police cadets who go to school in uniform. It is a commuter school with no dormitories. The Chancellor, we were told, is a very philosophical man who personally named all his buildings after prominent artists and scientists. One building is named both Newton and Galileo Hall, presumably because he was torn between the two. After lunch, we headed to orientation for a discussion of the Tiputini Biodiversity Station (TBS) and Galapagos Institute for the Arts and Sciences (GIAS). Rather than describe the content of orientation, which was all over the place, I will incorporate its materials into relevant portions of the narrative.
After orientation we retired to our hotel and slept off the altitude fatigue. The next day would be a travel day, but unlike the one before. We’d be heading into the Amazonian rain forest, down two rivers, and into the “heart of darkness”.
Figure 1. Our route from Coco to the Tiputini Biodiversity Station (TBS).
May 25
Journey to Tiputini
Today we traveled. First, we took an airplane from Quito to Coco (a distance roughly equal to that between Chicago and Champaign). From Coco, we proceeded to the Rio Napo on a short bus ride. After a two hour boat ride downstream (southeast) on the Rio Napo, we took another bus to the north bank of the Rio Tiputini. Another two hours east on the Rio Tiputini and we arrived at the Tiputini Biodiversity Station (TBS) (see Figure 1 for our route from Coco).
Before our first river passage along the Rio Napo we stopped at a small town with an interesting assortment of domesticated animals. Here we handled Toucans and Toucanettes, squirrel monkeys, and brown capuchins. I will leave discussion of the monkeys for our journey back from Tiputini, when we had more time to observe them.
I spent the entirety of these combined boat rides up front, in the bow. As it rained heavily and I lacked a poncho, I simply covered myself with the unused portions of the luggage tarp. The water along the Napo and Tiputini rivers is brown with sediment, yet otherwise considered potable (with some minor treatment). The boat was piloted in the back and guides on the bow helped navigate by pointing out large branches and vegetable rafts floating down river. These rafts, which can consist of several tree boles and mounds of dirt caught in connecting root sections, are often posited as the natural vessels responsible for bringing un-seaworthy colonists to faraway islands (such as the new world monkeys from Africa to South America, or tortoises from South America to the Galapagos Islands). They also proved singularly treacherous to our boat, which was overloaded and in fear of capsizing.
In addition to the thirteen members of our group from the University of Illinois, sixteen additional students from Moravia College—a small liberal arts school run out of Bethlehem, Pennsylvania—would join us at TBS. These students were lead by a Dr. Bevington, a soft-spoken plant physiologist with absolutely no hair (not even eyebrows). We came to call these students “Moravians,” and they soon became the brunt of our insatiable desires for a good inside joke. Were the Moravians a cult, or a hereto unrecognized race of humanity? How many Moravians does it take to screw in a light-bulb? Three Moravians walk into a bar…
Our combined cargo weighed down the boat considerably, which forced us to come to a stop and confront oncoming wakes perpendicularly, all the while fearing vegetable rafts as an arctic captain fears icebergs. At one point along the Rio Napo we came close to the shoreline, which was red with oxidized irons. Red mud is common in areas experiencing high amounts of rainfall as the other nutrients are leached out of the soil. The plants do not require iron and it accumulates until the ground assumes the color of blood. The tropics, which provide a great exposition of competition and predation, further lend themselves to Alfred Lord Tennyson’s oft-quoted dictum “nature red in tooth and claw”. Add soil, and you’ve got the Yasuni National Park.
While we navigated the river close to shore, one lonely child attempted to hitch a ride. We all laughed at this somewhat pathetic display. I wonder, does anyone ever successfully thumb a ride along tributaries of the Amazon?
After the Rio Napo we entered oil country. The state of Ecuador owns all the mineral deposits in the nation and sells the drilling rights out to foreign companies—Sinopec, a state-owned Chinese firm chief among them. Guards armed with machine guns and lapels labeled “Oil Security” demanded passports and screened our luggage immediately after setting foot in the national park. Several students were told to put away their cameras—pictures were forbidden in the oil zone. This no-compromise attitude went with the wind when several female students asked permission to pose with the guards. You can’t put a short leash on human nature.
Untapped oil reserves less than a hundred miles northeast of TBS are estimated to contain upwards of one billion barrels of oil. Recently, Ecuadorian president Rafael Correa has ransomed these oil reserves to the world: for a payment of $350 million a year, the oil reserves will remain buried underground. This fee may sound unreasonable, but Ecuador owes $15 billion in outstanding debt--much of it to the World and Inter-American Development Banks. Is there any chance the world will pay (or relinquish some of the debt)?
“What do you think?” said Kelly Swing, the director of TBS, in a cynical voice that left no doubt he meant “of course not”.
The history of US relations with Ecuador and Nicaragua provides an interesting contrast. The story of US intervention in Nicaragua is one of shameful and nonsensical meddling—first we backed a military dictatorship, and then we spent years attempting to stifle contra rebels to prevent a communist domino effect in Latin America (using the same faulty logic that got the US into Vietnam). Nicaragua is an agrarian country and one of the poorest and least populous in Latin America. Ecuador, by comparison, contains a large impoverished population and lucrative nationalized industry (with close ties with China to boot). That is, Ecuador is clearly socialist, with a prominent poor demographic with a history of ousting presidents it doesn’t care for. Why did the US meddle in Nicaragua but ignore Ecuador? One might as well ask, why do fools fall in love?
While we were forbidden to take pictures, it isn’t clear why not. All we saw were an airplane hanger and some flatbed trucks hauling pipes and other supplies. The roads and infrastructure necessary to bring supplies and staff in and out of Tiputini is provided by the oil companies. Unfortunately, any study attempting to measure the ecological footprint left by the oil companies is stymied before it gets off the ground. Government sanctioned secrecy prevents an accurate measure—ironically, the measure which may add weight to Correa’s ransom. While we didn’t see the actual oil-drill site, I did notice that the forests surrounding the road were thick and untouched. It’s possible that an oil giant may be the lesser evil to population expansion and slash-and-burn subsistence agriculture. One thing is clear: the scientific tool-kit of the intrepid ecologist attempting to measure the oil footprint ought to include an entourage of feminine eye-candy.
It was dark by the time we arrived at TBS. The station is maintained by a group of live-in cooks and custodial staff, naturalist guides, and a few graduate students. The camp is split up into the main kitchen area, a water treatment station, a library and two main bungalow neighborhoods. Electricity is provided by a generator which is only on for a few hours in the morning, again in the evening, and off promptly by 8:30 pm. The library is the only air-conditioned structure, on account of the books. The humid atmosphere would reduce its hundreds of volumes to a pulpy mess without this special precaution.
After settling in and eating a light supper, we went back to our respective bungalows. We were told that the next three days (May 26-28) would be spent on biodiversity surveys to familiarize ourselves with the local flora and fauna.


Figure 2. The brown, sediment rich waters of the Rio Tiputini




May 26-28
Biodiversity Surveys at the Tiputini Biodiversity Station
Team Jose
Team Maller
Dr. Mackie
Eddie
Yukari
Lindsey
Megan
Brian
Stephanie D.
Stephanie M.
Katie
Jennifer
Kristen
Patrick









Waking up on the morning of May 26 I felt that peculiar sensation of complete ignorance of the surrounding landscape. What was hidden behind the dense heliconia shields cloaking the mid-canopy? What sorts of strange critters wandered under the leaf litter and along the tree boles? How close was I to a jaguar or an ocelot, stalking a herd of foul-smelling peccary along the salt-licks? Where were the anacondas hidden? What flowers were blooming that morning that would wither and die before evening? What machinations were capuchin monkeys dreaming up in their big brains? These thoughts buoyed my spirits and put me into a better mood than I am accustomed meeting in the early morning.
While on the trail to the kitchen I met a trumpeter bird, who eyed me curiously and kept pace directly in front of me. This bird is called Lecho—the fighter—and the scientists and staff at the camp take care of him in return for his alarm cry. When Lecho sees a snake, he ferrules his feathers and makes a deep bellowing noise. I can’t think of any comparable noise, so I’ll mention only that it sounds nothing like a trumpet. Lecho allowed himself to be pet lightly along his feathers. A few students (surprisingly, not including myself) tried lifting Lecho from the ground and gave him occasion to live up to his namesake. Lecho was quite popular around TBS. Everyone who saw him announced his name warmly.
After breakfast our group split in two, each with its own naturalist guide (see Figure 2 for the group compositions). I was placed on team Jose. Jose was a soft-spoken man with extremely sharp eyesight and a reliably dry sense of humor. For instance, asked whether one could eat the fruit of a clarisa tree, he responded “yes, and then one will die.” Jose would often call to Eddie, who could speak Spanish, in a long drawn out “Eddddddiiiiieeee.” These nuances rapidly became running jokes in our group. Team Jose and Team Maller also entered into a friendly rivalry, centering on which guide could spot the parasites in the fur of a wooly monkey at one hundred meters. Our goofiness knew no bounds.
Our first hike into the jungle was also the most eventful. Prior to departure, we spotted what looked like an owl in size and shape but turned out to be a great potoo. The potoo was spotted at the edge of camp and never would have been noticed if Jose didn’t already know the nesting tree. We also saw a red assassin beetle. This insect squirts a caustic chemical at predators. The chemical is inert under physiological conditions and activated only when mixed with a certain enzyme. The assassin beetle mixes these ingredients outside the body by secreting them from separate nozzles (attached to distinct exocrine glands). I learned these facts shortly after inspecting the beetle up close. One might attempt to isolate these compounds and mix them experimentally, measuring the temperature as a function of time.

Tiputini also houses an orchid farm. Orchids are a peculiar type of flowering plant belonging to the family Orchidaceae. They are monocoteyledons (containing only one embryonic leaf) with parallel veined leaves. These plants are known for specialized floral structures that facilitate in pollination. Orchids grow epiphytically along the surfaces of large perennials, thus the members of the garden were obtained mostly from tree-falls. Orchids possess startling beauty for the sake of attracting pollinators—one is filled with a healthy respect for Hymnepteran and Lepotern who settle for nothing less. Alternatively, one is awed by a flower that should so discriminately specify its pollen bearer. Our one encounter with a wild orchid was decidedly esoteric. During the last few days of our stay at TBS, the river rose by three meters. The steps we took up from the river up the steep banks were two-flights underwater. It was during this time that we were schedules to fish for piranhas—an event all the students had been looking forward to.
When the river floods the water is diverted through a series of channels. As high water levels are not conducive to fishing, Maller guided us through one of these channels to find a suitably shallow spot to throw in our line. Our gear was quite simple—some fishing line wrapped around a block of wood baited with raw chicken. While under normal water conditions this set-up is supposed to work so well the bait hardly has time to sink a few inches (according to the boatman), we failed to catch anything. However, as we navigated our boat through the canopy of trees we once stared up at from below, Maller suddenly grabbed at a branch and tore it free from its waterlogged bole. This branch contained a beautiful white orchid with a hint of purple along its petals. Our experience up in the canopy also exposed us to red ants, which swarmed us each time a branch snapped off at eye level was allowed to fall into the boat. Stephanie D. was bitten by several of these ants and reduced to tears—she described it as an aching burn that came in wave after excruciating wave.
The high water levels also gave us occasion to see a three-toed sloth. Sloths are indeed slow, their movements deliberate, and their faces always seem to betray a curious self-satisfied grin. The coat of these animals is slightly greenish in color owing to the algae that grows there (a stone rolling at sloth speeds tends to gather a little moss). While many people, both in Costa Rica and at TBS, described sloths as sacks of dirty laundry hanging from tree branches, this was not my impression of them (few things are filthy enough to compare to my dirty laundry). I saw them rather as a primate with some degree of cryptic coloration—not dirty nor demeaned by their slow movements. This particular sloth looked down at us without concern, scratched his backside, and hung from the underside of the branch. When we returned to the same spot an hour later, he was in the same position (and scratching at the same itch). While sloths are often described as entirely arboreal, these animals have a curious habit of coming down to the ground to defecate. Most arboreal primates simply allow their fecies to fall down to the earth from the upper-canopy. I can attest to this habit in mantled howler monkeys, who somehow manage to end an afternoon siesta with every member simultaneously crapping. Sloth fecies is described as a single solid pellet, which they burry at the base of the tree. Some authors (Forsyth & Miyata 1984) propose that this habit owes itself to the small day ranges of the sloth, who seeks to fertilize the few trees it exploits.
I will refer the reader to “The Ways of Tropical Leaves and Roots” for my observations on drip-tip leafs and stilt and buttressed roots. The rainforest is not particularly hot (never did the temperature exceed ninety degrees Fahrenheit). Although Tiputini lies near the equator where the sun beats down from directly overhead, several phenomena conspire to keep absolute temperatures down. Cold air moving into the tropics from the north and south aids in the rapid cycling of hot damp air into the upper atmosphere, where it cools down and precipitates. The high levels of rainfall, in turn, support thick vegetation, which provide an increased surface area on which water can be evaporated. This increases rainfall patterns further. Not only does moist air heat up more slowly than dry air (due to the high specific heat of water vapor), but the increased rates of evaporation cool the rainforest. Moreover, as much of the sunlight is shielded from the forest floor by the canopy above, the temperatures experienced by a naturalist on the ground are entirely bearable.
The trail to the north took us through some areas of dense vegetation characteristic of jungles and into perennial forests characteristic of climax communities. These two habitat types were neither sharply defined nor consistently populated. In jungle areas multilayered trees and large heliconia shields capture what little sunlight penetrates to the forest floor. Jungles are also rich in Cecropia trees—a fast growing, shade-intolerant colonizer of recently formed canopy gaps. In the climax communities, large woody trees with monopodial tree crowns block out most of the sun and no vegetation save for small (less than 2 meter) saplings grow in the dark under-canopy. Light intensity forms the most significant vertical gradient in the rainforest. For a longer discussion of the concept of jungle and climax community forests see “Canopy Maps”.
Along climax communities and jungles alike, lianas descend from the upper canopy all the way to the forest floor (sometimes as far as 50 meters below). Some vines and lianas form characteristic spirals, analogous to the spirals of a telephone cord, which allow them to stretch out should an attached tree fall to the ground. Thus, a vine can weave through the canopy of more than one tree. These climbers get their start in disturbed forests and grow upwards. Their presence in both climax and jungle communities likely reflects their ability to occupy multiple tree crowns, colonizing new member trees as they emerge from below. It’s interesting that climbers include members of families—such as legumes—that also contain large perennial trees. One type of vine, called the “monkey ladder” for its utility to fallen primates, has characteristic flat-disks along its spirals (but watch out, an almost identical vine contains poison!). I didn’t notice whether the spirals tended to be either right-handed, left-handed, or both. Considering that climbers do not form a monophyletic clade, there may very well be both. Climbing the lianas can be fun, as they can certainly support a human of sizable proportions (at least 225 lbs.), but it should be noted that what comes up must come down.
The forest floor is not covered with a thick layer of leaf litter. Only about 5-8 cm of detritus covers the mud. Millipedes, which differ from centipedes in having two legs per body segment rather than one, are an abundant constituent of the forest floor. These large insects (around 13 cm) eat decaying logs and leaf litter and can be handled without fear of injury. When threatened these millipedes roll up into a ball. Katydids and mantises are also common. These insects blur the distinction between camouflage and mimicry. Some mantises—often called stick bugs—literally had to be touched by Jose before we could distinguish them from green stems. These mantises fly away when handled, but they are not particularly agile. They likely rely on simply not being seen to avoid predators.
Once, walking along the trail, Jose pointed down towards some fallen leaves. “Look,” he said. I saw nothing. He pointed closer. Still, I saw nothing. Finally, he bent down and touched a leaf-colored object, which leaped in a very un-leaf like manner. He was pointing at a lanciferous frog so completely concealed that only movement allowed my brain to tentatively trace an outline. Spotting these cryptic creatures is extremely difficult and we undoubtedly missed many interesting specimens, but the skepticism required to look at a stem like something that may be a grasshopper, a leaf like something that may be a frog, and a vine like something that may be a boa constrictor, can be learned. It is somewhat ironic that the mimetism that interests us most is the most likely to escape observation.
However, some things really are just what they seem. One day, walking along the trail just behind Jose, I spotted a moth with a brilliant means of camouflage. This moth actually produced external mushroom caps, which protruded out of the exoskeleton to produce an effect indistinguishable from a fruiting fungus. In fact, it was no mimic at all, but a moth infected with Cordiceps. These fungal parasites are species specialists that ultimately kill their hosts, leaving them clinging to a tree. Jose was much amused as I wrote “fungus moth” in my notebook. Later we encountered two dead grasshoppers afflicted with another species of Cordiceps. We never had the chance to see a live insect struggling to survive with the fungus. These fungi call to mind the analogous case of the lancet fluke Dicrocoelium dendriticum. This fluke infects the brain of certain ant species, causing them to migrate to the tops of grass blades. When grass-grazing animals inevitably eat the ants, the fluke migrates to the animal’s liver and takes up residence. Might Cordiceps similarly infect the brain of its hosts, sending them scurrying up tree boles to facilitate in the dispersal of fungal spores? Shortly after these eerie encounters we ran into a tree that had twisted itself into a pretzel (presumably reflecting growth towards small light gaps, recorded in time as the tree matured and the bole became thicker). Paradoxically, in a rainforest the most absurd things are the most straightforward.


By far my favorite example of mimicry occurs in a species of katydid observed along the first of our night-walks. This insect mimics a dead leaf not only in coloration, but in the possession of false herbivory scars as well. Jose informed us that this particular katydid is common in deciduous rainforests during the dry season, due to the abundance of dead leaves to mimic. Some katydids are colored a brighter green to mimic live leaves, others living in the hallowed out center of a tree bole are colored black. Blending into a surrounding gradient requires more than accurate pigmentation, however. Many species are also countershaded—for instance the green iguana—in order to mismatch the color scheme one would normally expect in a monochromatic object. That is, the lizard is darker green on top but lighter as one observes the scales from dorsal to ventral surfaces. Along the ventral surface, the lizard is white. Countershading is common amongst fish that can be preyed on from above or bellow—it allows the fish to appear two-dimensional in a world where mortal threats come from all three. The iguana is arboreal, rather than terrestrial, and similar conditions are met (life in a tree is three-dimensional). This particular iguana was easy to catch and rather obliging come photograph time. I simply snatched it (sex unknown) from a tree bole and let it sit on my open palm. Later, I set it along the rim of my safari hat, where it would have stayed for some time if it wasn’t returned to its tree. I should note that even terrestrial species benefit from countershading if predators come at them from above.
Another interesting camouflage adaptation comes in the form of outline obfuscation. Some reptiles exhibit regular geometrical patterns on their scales to melt their outline into the surrounding gradient. We observed a species of anole lizard with a similar type of patterned camouflage, only it clashed with its gradient (a leaf, in this case) making it easy to spot. When scared onto the forest floor, this anole disappeared entirely.

However, just when stealth appeared to be the golden rule of the rain-forest, we observed a blue morpho butterfly (Morpho didius). These enormous (~15 cm wingspan) butterflies are abundant in the forest and around camp. Similarly conspicuous are the poison dart frogs. These frogs accumulate toxic alkaloids (a type of organic molecule that can be isolated in alkaline solution) in their skin. While we didn’t see many poison dart frogs, the rainforests along the La Suerte River in Costa Rica were swarming with them when I visited in December. During one walk we came upon a frog reputed to be so toxic that merely touching the surface would cause “immediate death”. This was probably Phyllobates terribilis. These frogs are called “poison darts” as their volatile alkaloids are used by natives in the tips of spears and arrows. I vividly remember allowing one of the Costa Rican variety (a black frog with green circles) to hop up onto my hand after a local guide told me their poison was only harmful when ingested or rubbed into the eyes. I washed my hands afterwards, though for the rest of the day I could feel an aching pain along the side of my palm where the frog had first landed. These dart-frogs belong to the family Dendrobatidae and a new species may have been found by Kristen, Ed, and Stephanie M. while hiking with Maller. I have reproduced an excellent picture of this frog taken by Stephanie M. If it does turn out to be a new species, they have gone on the record that it should be called Dendrabales mallerensis (or perhaps Phyllobates mallerensis). I wholeheartedly approve.
Similarly, a large spider with bright yellow abdomen—called the golden spider—was spotted in its web blocking the way of a narrow trail. When the sunlight hits this spider’s web it shines like strings of gold, hence the name. One reason cited in favor of conspicuous webs is that they prevent the capture of birds (which can tear the web apart). For instance, studies have shown that conspicuous zig-zaged strands of silk called
stabilamenta built on the webs of orb-weaver spiders decrease the number of bird collisions. Might the golden spider have “wanted” us to see its web, rather than walk right into it (thus ruining it)? If so, we were certainly on the same page.
Many tropical birds are brightly colored. On our second days of hikes we spotted a group of three bright red scarlet macaws ( Ara macao) feeding in a tree crown close to the ground. Macaws are parrots of the family Psittacidae, and many (if not most) species are gregarious and green-feathered (including the green chestnut-fronted macaw A. severa we would spot later on the canopy tower). I was able to get some great footage of these animals and would have been able to film them sweeping directly overhead if my camera didn’t malfunction due to the humidity. This is a common problem in the rainforest—electronic devices need to be kept dry. Mushrooms of all shapes and sizes were observed, from the toxic red-capped specimen to the devil’s penis. The red-capped mushroom is mortally toxic if ingested, while the devil’s penis merely excretes a putrid odor when it fruits.
Generally, the reasons for being inconspicuous are clear, even if organisms employ multifarious means of achieving that end. If you can’t be seen, you can’t be preyed upon (similarly, if you can’t be seen by your prey, you can feed upon them). However, the reasons for being conspicuous are varied. Some toxic organisms, like the Dendrobatidae tree frogs, exhibit colorful warnings to predators. It is interesting to note that Morpho butterflies are palatable. One might expect from their dazzling coloration that they are exhibiting a warning sign to predators, like the orange monarch butterfly, but this is not the case. Moreover, the familiar explanation for elaborate plumage in birds relies on the presence of sexual dimorphism (drab females select the most colorful males). However, both male and female scarlet macaws are bright red. As a student of ecology, I find the rainforest abounding with incongruence and aberrant beings. Considering that rainforests contain some 50% of all species on the planet, is it not unreasonable to say that either we are all aberrant, or none of us is?
Might the functional acuity of a conspicuous but non-toxic butterfly help explain the early evolutionary stages toward warning coloration (also called aposetism)? I suspect it does and would applaud anyone who could quantify the benefit a non-mimicking, palatable insect receives from conspicuous coloration. I’ll mention that the owl butterfly, another interesting specimen we saw on our hikes, displays a conspicuous white spot on its wings. The spots on these wings are thought to draw predators’ attention away from the insect’s main-body. This trade-off may sound about as reasonable as the no-win hypothetical of a man forced to choose between two loved ones dangling off the precipice of a cliff, but that remains to be tested. Also, though we only saw the morphos when they displayed their brilliant blues, they in fact possess a brown wing covering that allows them to blend into tree bark. Could a butterfly evolve coloration to distract predators away from more vital areas, assume a diet of that results in the accumulation of unpalatable chemicals, and finally co-opt the conspicuous coloration as an aposometic warning sign? Perhaps.
Tree frogs, with their bulging eyes and enormous hind legs, are the dominant amphibian in rainforests. Comparatively, in temperate latitudes the dominant amphibians tend to be salamanders (which are scarce in the tropics). For some reason, salamanders have failed to radiate as much everything else has in the neotropics.
While we did manage to see some monkeys, these sightings were always brief. Wooly monkeys are the most common at Tiputin. They tended to congregate around a fig tree adjacent the library. Tamarins, spider monkeys, red howlers, squirrel monkeys, and brown capuchins were also present. I was able to film a lone spider monkey nestled on the uppermost branch of a tree about a kilometer distant through the eyepiece of a spotting scope. This monkey sat all by himself and seemed to enjoy the isolation. Is it possible that gregarious animals need alone time? I will discuss the monkeys further as they relate to the research projects of TBS’s resident graduate students.
One day, walking across a stagnant stream filled with leaf-litter, Dr. Mackie suddenly stopped and exclaimed “Bio-gas!” As no one knew what this meant, he explained that the stagnant creek was bubbling. These bubbles were not coming from fish or any other aquatic animal, but from methanogenic bacteria. These charming bacteria are responsible for the breakdown of cellulose in ruminant animals (e.g., cattle) and flatulence in primates. Unlike aerobic respirators, like animals and plants, methanogens thrive in low oxygen environments like marshes and the cecum of large intestines. Methanogens belong to the domain archeabacteria, one of the three major divisions of all living things on the planet earth. The University of Illinois’ own Carl Woese is the man responsible for much of the brouhaha over methanogens, having placed them closer to eukaryotes (nucleated cells) than to common bacteria (or eubacteria). While most living things oxidize carbon fuels and emit CO2 for energy, methanogens use hydrogen gas to reduce CO2, releasing combustible methane gas (CH4). This is the source of the common myth (which is probably very true) that if a man lights a cigarette in a poorly ventilated outhouse, he’ll explode.
“So, if we mix up this creek and throw in a match it’d go poof?” I said to Dr. Mackie.
Dr. Mackie: “Mike, get a stick.”
Using a lighter, we attempted just this. While Mike stirred up the creek, it bubbled vigorously. Unfortunately, we failed to light this gas. The gas does not smell like a fart as methane is odorless. Sulfur is the guilty emission of flatulent animals.
Later still we came upon a pond and a large group (~10-15 individuals) of Hoatzin. These large and clumsy birds are known for one outstanding trait: they are the only Aves to utilize foregut morphology. As a rule of thumb, mature leaves tend to be rich in structural compounds (such as latex), while mature leaves are rich in toxic chemicals (such as terpenoids). Foregut morphology is common amongst folivores monkeys, who preferentially feed on young leaves. Howler monkeys (Genus Alouatta), which feed in large part of young leaves, possess a large foregut. Passing plant material through the foregut allows for the detoxification of defensive compounds before the food is passed through the rest of the alimentary canal. Comparatively, animals that eat on high-fiber plant material tend to have enlarged cecums (or hindguts). Oftentimes, when attempting to infer the adaptive value of some trait, it helps to see convergence onto that trait in separated lineages (see “The Way of Tropical Leaves and Roots”). The presence of an enlarged foregut in Hoatzin, which eat immature leaves rich in defensive compounds, adds weight to the argument that foreguts are evolved specifically for this purpose.
Alfred Russell Wallace, the co-discoverer of natural selection, once said: “Ants are found everywhere”. This is not hyperbole, it is the literal truth. One species of ant (Myremelachista schumanni) is the subject of an independent research project discussed at length in “Tending the Devil’s Gardens,” so I will pass over it here. Ants belong to the order Hymenoptera along with wasps and bees, all of which possess both eusociality and a unique pattern of inheritance called haplodiploidy. The ants are eusocial, as opposed to gregarious, as they contain sterile workers and only one reproductive queen. If one dwells on the lack of individualism possessed by each individual ant, one misses the beautifully complex associations these organisms form with other species. Leaf cutter ants (genera Acromyrmex and Atta) provide an interesting example.
One day, hiking through the rainforest, Jose had obviously gotten lost. We had strayed off the beaten path and he spoke softly to himself, often changing direction and then stopping suddenly and trying to reorient himself to some landmark. While we hiked aimlessly through the rainforest we came upon a column of leafs dancing along the forest floor. These dancing leaves were being carried by the leaf cutter ants, which picked out specific tree species, cut out leaf trimmings, and carried them into their nests underground. These enormous nests had several openings, up the ants streamed to and fro only three. I was already somewhat familiar with leaf-cutter ants from my experiences in Costa Rica, where I observed a colony on one side of the river harvesting trees from the other. This forced all of the ants onto a narrow rope bridge, spanning some fifty meters across the Rio Suerte.
Leaf-cutter ants do not eat leaves, but use them as a growth medium for specific species of fungus. These fungal species are never found outside the ant nest and ants never eat anything but the fungus. In the jargon of ecology, this is called an obligate-mutualism—neither member could survive without the other. Haplodiploidy is a phenomena caused by the unique reproductive habits of Hymentopterans. The queen ants receive a lifetime’s worth of sperm in one nuptial orgy (although there exists some evidence that multiple males take part in the orgy, these complications will be ignored for the sake of brevity—see “Journey to the Ants” by E.O. Wilson). Sex determination is mediated by whether a developing egg receives a sperm—which is controlled by the queen ant herself—or develops parthenogenically (e.g. as a clone with only ½ the queens DNA). The half-clones develop into males, while the fertilized eggs develop into females. I mention this fact only to point out the importance of ants in the development of certain concepts in evolutionary theory—the phenomenon of haplodiploidy helped evolutionary theorists describe the theory of kin-selection.
While observing these leaf-cutter ants, Mike decided it would be interesting to suddenly introduce a barrier to the ant highway. As you can see from the photograph, this caused an ant pile up on either side (on the left, ants are returning to the nest with leaves, while on the right ants are leaving the nest to return to the tree). I performed some on site experiments myself. For instance, I lifted ants from the highway from the tips of their leaves. These ants would continue holding onto the leaf with their mandibles and walk normally. If the ants were turned 180 degrees, they would right themselves quickly and head back to the nest. If the ants were removed from the trail, they would wander directly back to it and back into the nests. If, however, the ants were lifted and placed near one of the unused entrances to the nest, they would sometimes wander around confusedly, usually entering the hole.
Toying with the ants interested me for a while, and I got to thinking about how ants navigate certain barriers. For instance, if I placed a tall barrier (let’s say 30 cm, or about one foot) in front of the ant highway, would they walk over it or around it. Similarly, would they act the same way if instead of a wall, they experienced a depression of 30 cm? Also, would their decision to go over or under the barrier depend on its width? What if a tunnel were added to the ant highway, thick at one end but thin at the other. Unless the ants could respond like fluids (which move at a constant volume/time, increasing the fluid velocity as the cross-sectional area decreases), the small end would slow them down considerably. How might an ant navigate more clever obstacles, like mazes or long tunnels that terminate at one end, placed in their path by a capricious undergraduate? Unfortunately, though I wanted very much to answer these questions, heavy rains during our period of data-collection for independent research projects drove these ants underground.
One day our group hiked right through a mass of advancing army ants (Genus Eciton). These ravenous insects kill all the arthropods in their path, and Jose let his otherwise calm countenance falter when he turned around and told us to “hurry up!” during this display. We did not observe, however, the host of ant-birds commonly associated with these advancing armies. Surprisingly, only a few students were harassed by the phalanx of predatory ants. There were diverse species of ants everywhere we looked. Tejedoras ants make giant nests along tree boles, while Azteca ants nest in the hallowed petioles of Cecropia trees. During our canopy map project I climbed up and collected leaves from several Cecropia trees, but was never bitten. These ants are reputed to defend their host-trees fiercely—it must have been luck that I wasn’t swarmed. My least favorite ant (and, for that matter, animal) was the bullet-ant. The locals call this the Conga ant. It is black and about 2.5 cm long. Jose, who had been stung by this ant, always cautiously pointed them out on the trail. He told us that when he was bitten (he meant stung, as the bite merely allows the ant to hold on) he suffered from fevers and aching pain all night. During the canopy map project, Lindsey pointed to my walking stick and shouted “Brian! Conga ant!” I shrieked like a woman and tossed the stick away. After she admitted she was joking, I very reluctantly picked the stick back up.
At night, the rainforest changes dramatically. The stick-bugs and dead-leaf mimics are easier to see at night (with the aide of a good flashlight) than during the day. These insects are nocturnal to avoid both predation (dead-leaf katydids feed on green leaves, making them conspicuous while active) and desiccation (leaf-mimics, like leafs, have a high surface area to volume ratio—at night they experience less evaporation). Flash-lights also allowed us to see past cryptic coloration. The eyes of many nocturnal beasts contain a specialized reflective structure called the tapetum. When light is shined on the tapetum, the eyes glow (A bright red-orange in the case of caiman croc eyes. I should mention here that tropical naturalists don’t wear mining helmets merely to leave their hands free, but to decrease the angle light reflected of the tapetum has to travel before it meets the eyes. Thus, mining helmets increase the chances of catching the eye-glow of many nocturnal animals and I suggest students invest in them). We used this method to find dwarf-caiman crocodiles along the river at night.



Large spiders were more commonly seen at night than during the day. The most prominent among these was called the pseudo-scorpion (or was it the pseudo-spider?). The explanation given by Jose of whether this creature was a scorpion pretending to be a
spider, a spider pretending to be a scorpion, or something entirely different pretending to be either, led us round and round in circles. In fact, no one looking right at this spider would confuse it for anything else. While Jose handled it, it used its sharp front limbs to stab into his hand, probing the meaty parts until he let it go.
Snakes are also more common at night, though we didn’t see any. We also didn’t see any lizards, but tree frogs were common. Initially, I believed these night walks would be treacherous and frightening, but in fact a few powerful flashlights and a skilled guide took all the fear out of it. I was primed for these walks after studying mantled howler monkeys in Costa Rica. In order to find my troop of twelve monkeys, I would wander out into the jungle before sunrise. At dusk, they would howl at the rising sun, and I’d rush through the forest to their sleeping tree to prepare for a full day of observation. The night gave me something else, an exchange of dialogue impossible under any other circumstances.
As we were searching for Caiman crocodiles, each student with a flashlight and Maller on the front of the boat with a large spotlight, the tarp atop our skiff removed so we could observe the night sky, Eddie turned to the group and said “look, that’s the North Star.”
“The north star?” we said. “Can you even see the north star from here?”
“I don’t know,” said Eddie. “Which hemisphere are we in?”
I had to laugh at this strange question, which had never occurred to me before (having always known with absolute certainty which half of the earth I was on). However, in an attempt to answer him, I paused. Which hemisphere were we on? I wasn’t entirely sure.





The Ways of Tropical Leaves and Roots

Epithet after epithet was found too weak to convey to those who have not visited the intertropical regions, the sensation of delight which the mind experiences…The land is one great wild, untidy luxuriant hothouse, made by nature for herself.
--Charles Darwin
Voyage of the Beagle

Here no one who has any feeling of the magnificent and the sublime can be disappointed; the somber shade, scarce illuminated by a single direct ray even of the tropical sun, the enormous size and height of the trees, most of which rise like huge columns a hundred feet or more without throwing out a single branch, the strange buttresses around the base of some, the spiny furrowed stems of others, the curious and even extraordinary creepers and climbers which wind around them…These, and many other novel features—the parasitic plants growing on the trunks and branches, the wonderful variety of the foliage, the strange fruits and seeds that lie rotting on the ground—taken altogether surpass description, and produce feelings in the beholder of admiration and awe.
--Alfred Russell Wallace

Tropical vegetation has a fatal tendency to produce rhetorical exuberance in those who describe it.
--Paul Richards
The Tropical Rainforest

Figure 1. Team Jose posing in front of the buttress roots of a Cieba tree.
Figure 2. Characteristic drip-tip leaf shapeWalking out onto the trails of the Tiputini Biodiversity Station, I was not immediately struck with an appreciation for tropical diversity. The jungle seemed like one homogenous green mass. I worried the ecstatic homilies of Charles Darwin and Alfred Russell Wallace were lost on me. For starters, I couldn’t see overwhelming diversity in leaf morphology. In the temperate forests of Illinois, leaf shapes vary idiosyncratically. Thus, anyone introduced to the differences between the leaves of a maple and an oak tree can reliably tell them apart afterwards. To contrast, in the Amazon rain forest most leaves are large ovals with a characteristic drip-tip (Figure 2). There are compound and palmate leaves, but little serration. In short, there is a paucity of characteristic variation. Sameness, not diversity, reigns.
However, as is true of most things in the rain forest, once I learned what to look for I saw what I sought. For starters, the ubiquity of one feature amongst diverse tree families occupying the same range should be instructive and not merely frustrating taxonomically. Why should all the trees converge upon the common oval shape with drip tip? Jose had a ready answer: drip tips facilitate water run-off. The problem with simple answers like these is they fail to provide proper context. Carbon dioxide enters and water exits leaves through tiny openings called stomata. Thus, when leaves take in carbon dioxide they lose water. Many species in temperate latitudes, as well as the tree species we saw at the high altitudes of Cotopaxi, possess structural adaptations to prevent drying out. It’s not immediately obvious why a plant should seek to keep water off its leaves—it requires special knowledge of the peculiar climate conditions and species composition of the rain forest.
Drying out is not a problem for most tropical plants. Tropical rain forests are humid and usually experience no less than 8 inches of rainfall a month. However, this does not in itself explain why so many plant species should converge upon a similar leaf shape. Only an adaptive explanation will suffice for this task, and my search for it paradoxically opened up my eyes to the existence of the leaf variation I originally missed. But here I make a digression.
While walking along the paths of the rainforest we came upon a large (~50 meters) cieba tree with giant buttress roots. The tops of these roots were well above our heads when our survey group stopped to take a group photo (see Figure 1). On the basis of the roots alone, I concluded that this tree must have been the same as one growing near the Tiputini library. Jose quickly dismissed this notion. The leaves were completely different, he said. The buttressed tree growing near the library was a fig tree (this explained the frequency with which it was exploited by groups of wooly and tamarin monkeys). My mistake was made more embarrassing by the fact that the cieba is venerated by indigenous peoples and an icon of neotropical rainforests. Again, I somewhat embarrassedly decided that tree identification wasn’t one of my strong suits. When I looked up at the umbrella-like canopy cover of the cieba tree, I couldn’t even see the leaves. All I saw were the dense epiphytes growing along the branches.
Figure 3. Stilt roots Buttress roots are singularly awe-inspiring. It was humbling to be dwarfed by the supports of a giant cieba tree. Smaller trees have a similar means for providing structural support—stilt roots. Stilt roots emerge from above the soil and grow downward, like a series of inverted branches (Figure 3). One particular stilt rooted tree, the walking palm, has long emerging stilt roots capped at the end with smooth wood. Amongst our group (and all other groups independently), this plant assumed the epithet “penis-palm.” The phallic supports of the penis palm worked swimmingly as makeshift walking sticks. On rainy days, abundant clay deposits made the well-trodden trails slippery and falls were common. One rainy day, a student in our group uttered the droll lament: “If I had known it was going to rain I would have brought the ole’ penis stick.” Shortly thereafter I lost my balance, caught myself with my penis-stick, and marveled that we were using the stilt roots for essentially the same purpose as the trees. Rain water washes away the soil along the floodplains of rivers, eating away at the solid foundation trees require to stay upright. Tropical trees tend to have shallow roots to tap into the nutrient rich top soil (the quality of the soil decreases rapidly with depth). Stilting and buttressing are two solutions to staying upright without extensive underground supports. We had simply converged upon the same trick, via our oversized brains.
So why should distantly related plants converge upon a common leaf shape? I literally couldn’t see the answer from where I was standing. Luckily, Tiputini has a tower emerging above the top of the canopy (~55 meters). From this height, I was better able to appreciate the density of tropical epiphytes. Epiphytes are plants that grow along the branches and in the canopy of other plants. Bromeliads (belonging to the same family as pineapple trees), orchids, lichens and tropical cacti grow epiphytically. These plants form thick mats along the canopy of cieba trees. According to Jose it can be difficult to notice when a deciduous cieba sheds its leaves due to the abundance of shade-intolerant epiphytes living actively along its branches. As epiphytes do not strangle the host tree (like the matapalo, or strangler fig) or tap into its vascular tissues for water (like mistletoes), they are not considered parasites. In evolutionary jargon, the type of relationship between epiphyte and host plant is called commensalism—the epiphyte gains and the host plant remains unaffected.
Figure 4. Bromeliads growing along the branch of a tree
Epiphytes do not converge upon the common leaf shape of most tropical trees. The leaves of many of the bromeliads I spied from the tower seemed more apt at gathering and collecting water than facilitating its run off (Figure 4). Walking along the trail afterwards, Jose pointed out an interesting epiphytic structure known colloquially as the capuchin champagne glass. Amongst new world primates, only capuchins are known to use tools. These big-brained primates, which come to the ground occasionally, have been observed using the “champagne glass” to collect water. While I’m not certain about the species-association, I believe these champagne glasses are structures used by epiphytic flowers to gather protein-rich water. Some epiphytes attract insects to water pools held in specialized structures, trap them inside, and excrete enzymes to digest their water soluble organic structures. The flower can then “drink” this water soup. These insects provide some key nutrients to the epiphytes, which cannot access the soil on the forest bottom.
All plants take up water from their roots, and not their leaves. Epiphytes are no exception, only the roots cannot reach the soil. Lianas, by comparison, appear almost like epiphytes with a lifeline to the damp soil. When our group came upon a clearing and Jose pointed towards a free-hanging liana (“you play,” he said), this was my first impression. These lianas were easy to swing from and could be climbed all the way to the top of the forest canopy. However, lianas and vines both start on the ground and grow upwards. These plants are rooted in the soil like their hosts. Epiphytes root themselves in the crotches of their host trees and along the thin film of symbiotic lichen-bacterial mats along the tree bark. Crotches make ideal locations as they tend to collect leaf litter, which can be broken down by symbiotic fungi to provide the plant nutrients. Water also contains nutrients and must be collected by epiphytes. This explains some apparently incongruous facts. For instance, the distribution of epiphytes is limited to humid lowland and cloud forests—wet places. Epiphytes keep their stomata shut during the day and fix carbon at night to prevent drying out, unlike their earthbound host-plants that fix carbon dioxide during the day. Cacti, which thrive in arid climates, are epiphytic in the tropics (succulent leaves are adaptations to prevent desiccation). Epiphyte leaves and floral structures capture water, rather than shed it. All of these facts point towards one general conclusion—epiphytes are water-limited. The host plants, by comparison, have to grow from the ground all the way up to the canopy—they are light-limited.
But merely not being water-limited does not explain why so many tropical plants have converged upon the drip-tip shape. Perhaps the defensive compounds of leaves are leached by the rainwater, and the drip-tip prevents the water from pooling and penetrating the cuticle. However, an observation made on yet another walk led me to believe that the water collecting leaf shapes of the epiphytes might explain the water shedding leaf shapes of their hosts. Walking along just behind Jose, prodding the ground ahead of me with my walking stick, I suddenly came face-to-face with a conspicuously naked palm tree. Most trees in the rain forest were covered in bark, which in turn was covered with a mat of mossy lichens. This palm, Jose explained, sheds its bark periodically to prevent “damage” from these epiphytes. Could the drip tips be leaf adaptations to prevent the establishment of epiphytes?
Nature is not as discontinuous as the terms we use to describe it. Although it may be true that individual epiphytes do not parasitize a host-tree, the combined effects of an entire ecosystem of epiphytes may weigh down branches, forcing trees to allocate more resources to structural support. Moreover, epiphytes often develop dirt heaps in their aerial roots. How does the dirt get there? Jose claimed that the epiphytes collect airborne dirt molecules, aggregating it around their roots. This explanation may be true, but it sounds frankly untenable. First, in all of my hikes along the rain forest I have never been able to kick dirt up into the air, nor have I ever seen dust play in the air. In fact, the rain forest doesn’t possess much of what a temperate naturalist would describe as dirt—the soil is wet and muddy, held down by surface roots tapping into the fungal mats decaying the thin layer of detritus on the forest floor. Alternatively, epiphytes in the crotch of trees are able to catch leaf litter and convert it into soil. Thus, many of the larger dirt heaps are found in tree crotches. This truism is so reliable that many host plants grow aerial roots to tap into these rich soils.
The picture one gets from the species dynamics of epiphytes is one of successional change. First, lichens attach themselves to the tree bark and provide both the structural support (in the form of bark “soils”) and the fungal communities necessary for other epiphytes (bromeliads and the like) to take hold. These larger and more complex epiphytes develop means to capture nutrients and form soil mats along key structural points in the tree. The next successional wave may well come in the form of strangler figs whose seeds germinate in these soil mats (strangler figs often start out in the crotch of well established trees). Strangler figs send down vines that fuse and exert pressure on the host tree, cutting off the transport of nutrients through vascular tissues. Eventually, these figs completely take over the host tree. Indeed, our first experience with a cieba tree afforded us a glimpse of this process in action. The fig was growing out of the base of the tree crown and its roots were already starting to fuse around the cieba trunk. Perhaps epiphytes, in addition to never being truly neutral in their effects on trees, also provide fertile ground for late-successional strangler figs to take hold.
Figures 5 & 6. The expected results for a research project on the epiphyte/host-plant relationship. Just-so stories like this one may lie on a slippery-slope for evolutionists. Merely providing logic to a structure does not establish its development as an adaptation for a particular life strategy. However, wide-spread convergence in distantly related trees begs that such scenarios be considered. Perhaps the reconstruction is testable. A regression analysis between the density of epiphytes and the frequency of drip-tip leaves along different geographical plots could establish a correlation (or not). If trees shielded from epiphytes produce more viable progeny than trees exposed to them, their deleterious effects could be quantified. One might also test for the leaching of chemical compounds from the leaves, or see what effect occluding the drip tips has on the leaves (both in the presence of epiphytes and with epiphyte “shields”). It’s difficult to divorce the causal effects of epiphytes and the climate conditions that allow epiphytes to grow. However, with a little ingenious prodding, the ways of nature can be revealed. The hypothesis is well known enough to be cited in tropical guides—it’s time to test it.
Lest I be accused of idle speculation, I have provided two figures (5 & 6) which present predicted results for the hypothesis that leaf drip-tips are adaptations to prevent the establishment of epiphytes. Figure 5 shows the results for an ideal regression analysis (see the Devil’s Garden block for a description of regression) in which nearly all the variability in drip-tip leaf frequency can be explained by epiphyte density. Figure 6 provides all experimental permutations of the two variables—shelided/unshielded and occluded/unoccluded leaves. “Epiphyte density” in Figure 6 means the density of epiphytes on a single tree (whereas “epiphyte density in range” in Figure 5 means the richness and diversity of epiphytes occurring in a given geographical range). In short, the expected results indicate that trees without epiphytes are fitter (produce more viable offspring) than the trees with epiphytes, and also that trees with occluded drip-tips have a higher density of epiphytes. Additional regressions might include the diameter of the branches verses the density of epiphytes on each branch. A long-term study would be very difficult, as this hypothetical project requires good operational variables for fitness, a means for epiphyte shielding, and study plots along a geographical epiphyte gradient.
There is a connection between the ubiquity of drip-tips and support roots. The connection is one of similar form with independent origin. Perhaps the drip-tip is just an easy-fix, which is to say that natural variation in leaf morphology can easily be honed in by selection on the drip-tip design. Combined with strong selection for the benefits conferred by drip-tips, convergence is the expected outcome. The tropics are a place of great diversity and specialization. Specialization is thought to come about through competitive exclusion. Are drip-tips the exception that proves the rule? Do certain changes in leaf morphology have nothing to do with the niche assumed by the plant? What sorts of changes are these? I can guarantee only one thing: whoever uncovers the answers to these questions will need a lot of support. I recommend the penis palm (Figure 7).




Figure 7. Enough said.
Tending the Devil’s Gardens

“But of the fruit of the tree which is in the midst of the garden, God hath said, Ye shall not eat of it, neither shall ye touch it, lest ye die.”
--Genesis 3:3





According to the indigenous peoples of the Peruvian Amazon, there exists a mystical dwarf, the Chuycacaqui, who wanders the jungle on one human foot and one hoof, assuming the likeness of the friends and family of weary travelers so he can lead them in circles until they are lost. The Chuycacqui dwells in gardens, called “Devil’s Gardens,” composed principally of the lemon-ant tree (Duroia hirsuta). These “gardens” are remarkable in three aspects: they are almost entirely monoculture (D. hirsuta), they persist over long periods of time (as long as 800 years), and they are invariably associated with the lemon ant (Myremelachista schumanni).
I first encountered the devil’s gardens on the morning of May 26 while hiking in a group on the first of many surveys of the local flora and fauna at Tiputini Biodiversity Station. Dr. Mackie called attention to a circular tree gap composed entirely of small (less than 3 meters) D. hirsuta. On closer inspection, most of the trees’ internodes contained enlarged cylinders (1-3 cm in diameter), each with a small hole through which tiny ants emerged. These hallow structures (called domatia, Latin for “small house”) are a familiar feature of plants that form symbiotic partnerships with other organisms. For instance, cecropia trees contain hallow stems and some species of acacia contain hallow stipules to house ants (an outgrowth of the lower leaf). These ants held their abdominal sections erect while walking along the tree branches. The trunk of the tree was covered in a green moss cut into by clear white lines—the ant “highways” up and down the trunk. Our guide (or what appeared to be our guide) Jose tapped hard on the branch near the enlarged cylinders, and then cut the branch open diagonally with a pocket knife. The hallow section inside was teaming with ants. Jose dabbed his pointer finger against the tip of his tongue and pressed it against the branch (sticking the ants to his finger), and started eating the ants. He offered the branch to me, and I accepted. The ants tasted exactly like lemon juice (complete with the burning sensation).
Here I followed the most obvious course imaginable to someone trying to frame a working hypothesis: I simply combined the two most striking facts about the devil’s garden into a tentative explanation. Did the ants secrete some sort of acid (perhaps citric acid, in keeping with the lemon theme) that was leached into the soil by rainwater, preventing the establishment of non-lemon ant trees? Were lemon ant trees endowed with some special adaptation for growing in acidic (low pH) soil? Our resident expert, Jose, provided answers to these questions. Yes, he said, the lemon ants produce citric acid. He claimed they secreted the acid directly into the soil, preventing the establishment of non-lemon ant trees. Somewhat skeptical, and curious about the prospect of doing a project on the ant/plant mutualism, I consulted the scientific literature.
I found absolutely nothing on the lemon ants amongst the books and collections of scientific publications in the Tiputini Library. Was it possible no one had bothered to study the devil’s garden phenomena? Using the glacial internet connection and the University of Illinois Library’s online gateway, I searched the most up to date publications. Tantalizingly, the ants were only recently implicated in the devil’s garden phenomena. Most scientists had just assumed the plants themselves secreted a toxic substance into the soil, preventing the establishment of non lemon-ant trees (this mechanism is called ‘allelopathy’). However, in a letter to Nature a graduate student named Elizabeth Mary Frederickson provided the first experimental proof that the ants tend the devil’s gardens (Nature 437, 495-496). Frederickson planted common Amazonian cedar trees inside the devil’s gradens, excluding the ants from one group but not the other. She found that the cedar trees died in the gardens with ants. Similarly, she excluded ants from some, but not all, of the cedar trees growing in one devil’s garden, and found that only the unprotected trees were affected (a result that makes no sense if the ants poison the soil, either directly or through leaching).
Frederickson even described the mechanism the ants use to kill non-lemon ant trees. The ants injected formic acid directly into the leaves, which developed necrosis within 24 hours. Within five days of exposure to lemon ants, most cedar saplings had lost all their leaves. The lemon ant trees don’t possess special adaptations to live in acidic soil; they merely aren’t attacked by the lemon ant. Moreover, the ant/plant mutualism is not merely maintained by an ant behavior to abstain from attacking plants with nesting space (in the form of domatia). Frederickson found that ants attacked cedar trees with domatia, but not lemon ant trees without accessible domatia. This suggests that the mutualism is highly specific (perhaps facilitated by the ants recognizing a characteristic chemical signature of the lemon ant tree).
Here it is necessary to defend Jose’s false impression that the lemon ants secrete citric (rather than formic acid) directly into the soil. It seems likely that the identity of the acid meant very little to him. However, most people are probably more comfortable consuming citric rather than formic acid. The former is familiar to our diets in the form of fruits. The impression that the ants secrete it probably emboldens otherwise shaky students to taste them (Some in Maller’s group went so far as to lick a column directly off the surface of the tree. They reported unpleasant burning and conversion to the “less is more” camp.) Really, the gullibility of the class (myself included) is more outstanding than Jose’s error. The word formic comes from the Latin root formica, for ants, from which the acid was originally distilled. Formic acid is a common stinging agent of insects in the order Hymenoptera, including bees and ants. More embarrassing still, all ants belong to the family Formicidae. Formic acid is the simplest carboxylic acid, and can be easily metabolized and eliminated from the body (leaving the question of why the plants can’t evolve a defense to it unanswered). Citric acid, which is stronger and structurally more complicated, would be decidedly out of place in an ant. Moreover, the suspicion that the ants secrete the acid directly into the soil is an only slightly less egregious error than the idea that the gardens could be explained by allelopathy (the orthodox scientific view prior to Frederickson).
Returning to Tiputini, I had no difficulty deciding what I wanted to study for our independent projects. Dr. Mackie assigned me to a team along with Yukari Ohtomo (animal sciences) and Katie Carberry (chemistry). Our group became “the lemon-ant group”. Hastily (we had only two days to prepare) we set out a scheme for answering some specific research questions with standardized data. First, we agreed to test for a pH gradient in the soil. While Frederickson’s results specifically refuted the idea that the ants affect the soil, we wanted to provide a definitive negative result to go against what everyone had been told by their naturalist guide. I also wanted to demonstrate the benefits each tree received from the ants. We discussed some ideas for quantifying the number of ants on each tree, and settled on the operational variable of trunk circumference (the idea being that larger trees have more nesting space, and hence more ants). For benefits, we went with distance to nearest non-lemon tree neighbor (to gauge how effectively the ants had cleared the area of colonizing trees).
We ran into problems immediately. Tiputini outsourced its lab work and had no pH meter for us to use. Katie suggested we use cabbage juice. A simple pH kit can be constructed by grating up a cabbage and boiling it in water. The water should turn a dark purple color. A cut-up coffee filter can be dipped in the water and then dried. The purple paper should turn pink in acidic solutions, and green in alkaline solutions. Using some solutions whose absolute pH we could determine (such as lemon juice for acid, baking soda for alkaline, and the processed water as roughly neutral) we could have jury-rigged a respectable apparatus. We were spared the burden of this innovation, however, when one of the Maravians offered their own antique pH kit. This kit, a few plastic containers for collecting samples, a measuring tape and a notebook compromised our repertoire of tools.
We set out into the jungle on the morning of May 30th, after a night of heavy rains. We started out going to the southwest on the Lago trail, but found it completely flooded. Luckily, after backtracking, we ran into one large devil’s garden (22 trees) and one solitary lemon ant tree close to camp. We made measurements of the circumference of the lemon-ant trees and distance to the nearest non-lemon ant tree neighbor in both plots. However, while we were making these measurements a troubling notion hit me. We had supposed that larger trees should have further neighbors on the basis of ants, but even without ants (or allelopathy) this relationship is expected for any tree based on the negative effects of shading. Large trees shade a larger area, and should limit the distance at which any neighbor can establish itself. While Katie and Yukari collected soil samples, I decided to measure the circumference of the lemon ant trees to the nearest lemon ant tree neighbor. The rationale for such a measure can be seen in the following figure:

Benefit (+)/Detriment (-)
Lemon ants
Shading
Lemon ant tree
+
-
Non-lemon ant tree
-
-

In other words, lemon ant trees benefit from proximity to a larger lemon ant tree neighbor because the ants clear away more land (which can be used for the establishment of new seedlings and prevents the establishment of allelopathic plants). While both lemon ant trees and non-lemon ant trees are negatively affected by shading, non-lemon ant trees are also negatively affected by the lemon ants.
While taking this data I also had a chance to make some general observations. For instance, when a branch bifurcates, the large cylindrical domatia occurs along only one internode (hereafter called internode 1). The other internode (2) is shriveled and easier to snap off. Along the trunk I saw several shriveled internode 2s broken off at the flower-end. I’ve included a picture with labels below. The picture one pieces together from this pattern is one of iterated pruning of the flowers on internode 2. This leads to bifurcation, and the establishment of a pair of internodes (1 & 2). I’ll return to this interesting phenomena in the discussion.
Using a pocket knife, I cut open the cylindrical domatia and observed the insides. These large growths have hallowed insides and store the larvae of the lemon ant, along with several adult lemon ants. While collecting some lemon ants and their larvae for pH testing, about five or six ants crawled up onto my hand. I felt nothing as they walked with their abdominal sections erect, but suddenly and as if in concert they lowered their abdomens and rubbed themselves against my skin. I felt an irritating burning sensation and rolled the now wet and juicy ants up into little balls, flicking them off my skin. It appears that the ant does provide some protection from herbivores. Also, holding the abdominal section erect while on the lemon ant tree likely prevents the ant from inadvertently poisoning it. As yet, I have found no evidence that the lemon ant tree leaves are anymore immune to formic acid than the leaves of the Amazon cedar.
Unlike my first encounter with the devil’s gardens, I did not find the ants actively walking along the outside of the tree. I also didn’t see the ant highways—those cleared away sections of green moss on the trunk of the tree. This was somewhat disappointing, as I was now ready to interpret these highways under a new light. With an ear swab in tow, I intended to test the pH along the highway with the pH of the healthy moss outside the highway. Formic acid, acting as a natural fungicide, is often used as a food preservative. It occurred to me that the ants may clear the path by simply dragging their abdomens along the highway (safely out of contact with the leaves). But the rain seems to have altered the behavior of the ants and none were active. This is an analogous case to the leaf-cutter ants who work continuously 24 hours a day, but never in the rain.
Katie and Yukari, meanwhile, had collected soil samples around the solitary (though tenanted) lemon ant tree. We choose the single tree for the gradient measures to minimize the additive effects of the other trees and provide a simple means of performing a regression analysis for the plot of distance from the lemon ant tree (independent variable) to pH (dependent variable). Soil samples from well outside the devil’s gardens, near the entrance to the jungle, and at 1, 2, 3, and 4 meters from the lemon ant trees were collected. On the way back to camp, I also collected some red ants from under the wooden steps to compare the acidity of an insect that uses formic acid as a stinging agent with the acidity of the lemon ants (which use formic acid as an herbicide). The pH for the soil was tested by taking 2 grams of soil and mixing it vigorously with 5 mL of water (measured in a graduated cylinder). The pH for the insects was tested by smashing up 20 ants in 5 mL of water, and testing the water with the insects still inside. We prepared our results and I drew by hand a best-fit line (I have since used excel to perform statistical analysis). Our data was presented to a stunned audience at the Tiputini Symposium on the night of May 31.

Results
For brevity, I will refer to the lemon ant tree as LAT (see the figures below). The data from the LAT circumference vs. distance to nearest LAT neighbor and nearest non-LAT neighbor were entered into scatter plots. LAT circumference is the independent variable (x-axis) and neighbor distance is the dependent variable (y-axis). Using Microsoft excel, I performed regression analysis on the two data sets. Regression analysis works by forming a best-fit line for the data points (“best-fit” minimizes the mean squared vertical distance between the line and the data points).
The regression analysis of the LAT circumference vs. distance to nearest non-LAT neighbor demonstrates a positive correlation between LAT size and distance (the larger LATs are further from non-LATs than the smaller ones). To contrast, the regression analysis of the LAT circumference vs. distance to nearest LAT neighbor shows a negative correlation (the larger LATs have closer LAT neighbors than the smaller ones). Regression analysis can be used to determine the equation of the best fit line and the proportion of variability in the data that correlates with variability in the independent variable (the R2 value). R2 values vary between 1 (100% of the data variability is correlated with variability in the independent variable) and 0 (no relationship between the data and the independent variable).

LAT circumference vs. distance to nearest non-LAT neighbor

circumference
distance
0.34
2.2
0.15
1.8
0.22
2.1
0.28
1.5
0.16
1
0.04
1.3
0.07
1.1
0.03
0.53
0.035
1.2
0.1
1.6
0.2
1.6
0.11
1.3

Equation for the best-fit line: y=3.43x+.939
R2 value= .53









SUMMARY OUTPUT
















Regression Statistics







Multiple R
0.731074







R Square
0.534469







Adjusted R Square
0.487915







Standard Error
0.336443







Observations
12
















ANOVA









df
SS
MS
F
Significance F



Regression
1
1.299556
1.299556
11.48083
0.006905



Residual
10
1.131936
0.113194





Total
11
2.431492
















Coefficients
Standard Error
t Stat
P-value
Lower 95%
Upper 95%
Lower 95.0%
Upper 95.0%
Intercept
0.939716
0.175702
5.348336
0.000324
0.548226
1.331205
0.548226
1.331205
X Variable 1
3.43136
1.012697
3.388337
0.006905
1.17493
5.68779
1.17493
5.68779



























RESIDUAL OUTPUT



PROBABILITY OUTPUT










Observation
Predicted Y
Residuals
Standard Residuals

Percentile
Y


1
2.106378
0.093622
0.291852

4.166667
0.53


2
1.45442
0.34558
1.077294

12.5
1


3
1.694615
0.405385
1.263727

20.83333
1.1


4
1.900497
-0.4005
-1.24849

29.16667
1.2


5
1.488733
-0.48873
-1.52355

37.5
1.3


6
1.07697
0.22303
0.695261

45.83333
1.3


7
1.179911
-0.07991
-0.24911

54.16667
1.5


8
1.042657
-0.51266
-1.59813

62.5
1.6


9
1.059814
0.140186
0.43701

70.83333
1.6


10
1.282852
0.317148
0.988661

79.16667
1.8


11
1.625988
-0.02599
-0.08101

87.5
2.1


12
1.317165
-0.01717
-0.05351

95.83333
2.2


Figure 1. The LAT-circumference vs. distance to nearest non-LAT neighbor with best fit line (pink).

Figure 2. The LAT-circumference vs. residuals (a measure of deviation from the expected line) for distance to non-LAT tree.
Figure 3. The percentage of the sample (x-axis) found at or below the distance to non-LAT tree (the steady increase indicates little sampling bias).

LAT circumference vs. distance to nearest LAT neighbor

circumference
distance
0.17
1
0.12
0.7
0.2
1.05
0.26
1.8
0.21
0.29
0.21
1.04
0.14
0.88
0.07
1.4
0.32
0.62
0.16
1.1

Equation for best-fit line: y= -.67x+1.11
R2 value= .013



Lemon ants in cut away section of domatia




SUMMARY OUTPUT
















Regression Statistics







Multiple R
0.115149







R Square
0.013259







Adjusted R Square
-0.11008







Standard Error
0.439432







Observations
10
















ANOVA









df
SS
MS
F
Significance F



Regression
1
0.020758
0.020758
0.1075
0.751425



Residual
8
1.544802
0.1931





Total
9
1.56556
















Coefficients
Standard Error
t Stat
P-value
Lower 95%
Upper 95%
Lower 95.0%
Upper 95.0%
Intercept
1.11344
0.407043
2.735438
0.025629
0.174798
2.052082
0.174798
2.052082
X Variable 1
-0.67441
2.056925
-0.32787
0.751425
-5.41769
4.06887
-5.41769
4.06887



























RESIDUAL OUTPUT



PROBABILITY OUTPUT










Observation
Predicted Y
Residuals
Standard Residuals

Percentile
Y


1
0.998791
0.001209
0.002919

5
0.29


2
1.032511
-0.33251
-0.80258

15
0.62


3
0.978558
0.071442
0.17244

25
0.7


4
0.938094
0.861906
2.080391

35
0.88


5
0.971814
-0.68181
-1.6457

45
1


6
0.971814
0.068186
0.164581

55
1.04


7
1.019023
-0.13902
-0.33556

65
1.05


8
1.066231
0.333769
0.80562

75
1.1


9
0.897629
-0.27763
-0.67012

85
1.4


10
1.005535
0.094465
0.228012

95
1.8









Figure 4. The LAT circumference vs. distance to nearest LAT neighbor (m) with best fit line (pink).
Figure 5. The LAT-circumference vs. residuals for distance to LAT trees (notice the greater deviation compared to Figure 2.

Figure 6. The percentage of the sample (x-axis) found at or below the distance to LAT tree (notice that 25% are above one, compared to almost 88% in Figure 3)

Side by Side Comparison


Figure 7. A comparison of the best fit lines for LAT circumference to distance to nearest non-LAT neighbor (blue line) and distance to LAT neighbor (pink line).

Figure 8. A comparison of the R2 values for the LAT circumference vs. distance to nearest non-LAT neighbor (right) and distance to nearest LAT neighbor (left). The low value for “LAT to LAT” suggests that variables other than size determine the proximity of the nearest LAT neighbor.

The pH gradient

Sample
pH
Water
5.0
Control
4.8
1 meter
5.0
2 meters
5.0
3 meters
5.0
4 meters
4.5
Mature Lemon Ants
3.5
Lemon Ant Larvae
4.8
Red Ants
4.8
Figure 9. The distance samples correspond to the distance from a single lemon ant tree (a one-tree garden).

The pH results confirm Frederickson’s (2005) hypothesis that the ants do not tend the gardens by affecting the soil. The value for the lemon ants (3.5) compared to 4.8 in the red ants and lemon ant larvae indicates that the lemon ants produce more formic acid than a typical Formicidae and that the high acid levels are achieved sometime after maturity. The reader is reminded that pH is a logarithmic scale. A difference of 1.3 between the pH of lemon and red ants means that the lemon ants are about 20 times more acidic (101.3).

Discussion

Our data can be interpreted ways: as an explanation of the benefits the trees get from the ants and as an historical reconstruction of how devil’s gardens are created. Consider the strong correlation between LAT size and distance to non-LAT neighbor. One could call this a positive result for the hypothesis that more ants corresponds to increased benefits. The costs of housing the ants should increase linearly, while the benefits peak at a critical colony size (a figure I was unable to recreate would show a line y=x for the costs and y=log(x) for the benefits). Therefore, data points should fall below the best-fit line for larger trees. However, this might not be the case for the simple reason that the biggest trees were probably the first to colonize the tree gap. After the first tree establishes itself, other lemon ant trees would grow around it, increasing the radius of the garden. The effect of the growing garden, therefore, would tend to inflate the estimate of the benefit the ants provide in the currency of distance to nearest non-LAT. In fact, after the garden is established the original trees might benefit by having less ants (letting the trees on the garden’s perimeter pick up the slack). Mutualism, the feel-good phenomena of the life sciences, is in fact inherently plagued by a conflict of interests. The LAT “prefers” a colony size that maximizes the benefits and minimizes the costs. The ants, on the other hand, “prefer” unmitigated growth. It’s not clear what the costs are of housing an ant population in hallow domatia. However, the presence of two different types of internodes, one with domatia and one without, suggests that the trees are not providing the maximum nesting space.
Contrary to expectation, the line for LAT circumference vs. distance to non-LAT neighbor has a negative slope (and not just a shallower positive slope). However, the data points are all over the place (R2=.013). In one sense, the results are not entirely surprising. The LAT neighbors may just be seedlings of the measured tree. Large trees may have more seedlings established near to them. However, variation in tree size is not reliably correlated with variation in distance to nearest LAT neighbor. Part of this doubtless reflects our paucity of data points. However, it does suggest a complex trade-off between the detriment of shade and the benefit of ants. The means of dispersal of the LAT is itself a complex subject. Colonizing (early successional) trees tend to have wide dispersion in order to have their seeds ready to germinate when favorable circumstances arise. However, once the garden is established, there are benefits to staying closer to the parent tree. In effect, it is both in the ants interests to increase the nest space of the garden and in the plants interests to limit benefits to close kin. Perhaps the ants effect dispersal patterns directly to insure the production of devil’s gardens. Again, no evidence supports this proposition. However, it would be an interesting thing to look for.
There is no pH gradient in the soil. The lemon ants were 20 times more acidic than the red ants. The lemon-ant larvae, however, were of equal acidity to the red ants. It’s appears that more acid is needed to function as an effective herbicide than would be needed as a simple stinging agent. Moreover, this increased acidity is correlated with maturity.
Mutualism is a fascinating subject. The lemon ant/LAT mutualism is a great model of the phenomena in a natural setting. However, it should be recognized that evolutionary theory does not predict perfect harmony in its conflated partnerships. Evolution predicts conflicts when one member seeks to limit the population size of the other. These conflicts are brought out most vividly when the costs of taking part in the mutualism are considerable relative the benefits. Still, it is frankly inspirational that in the struggle for life nature has united uncommon bedfellows (a tree and an herbicidal ant) together. Doubly so, that a fanciful tale of a fiendish chimera tending these sacred gardens should yield to an even more interesting tale of a colony of ants, persisting for hundreds of years, extending the phenotypic effects of their nesting behavior out into the composition of the forest itself.











Few things inspire more of a comforting view of Mother Nature than the idea that cures for our most devastating illnesses lie hidden somewhere in the bosom of some tropical plant or insect. This hope inevitably gets tacked on to a short list of tangible benefits the rainforest might offer to humanity (besides aesthetic pleasure). What if we tore down the habitat of a cancer-curing beetle? The treasures of a biological species are not recoverable—each extinction heralds the permanent end of some particular type of novelty. Each hectare of tropical forest cut down may contain thousands of unknown species, one of which may contain the sought-for panacea. It’s almost maddening to think about it.
I’ve always been a bit of a skeptic when it comes to these sorts of arguments. For starters, they are inevitably hijacked by charlatans and snake-oil salesman with miracle-cure tablets that fly under the radar of orthodox medicine. Much of the alternative medicines widely available in the states are “alternative” only in the sense that they have never been double-blind tested. Moreover, many of the people who espouse the potential of ethnobotany (including my host-mom on San Cristobal) lack any scientific or medical training. Evolutionary theory certainly biases the biologist in the other direction—towards the idea that nature is capricious and unconcerned with our health. Still, my experiences in the rainforest offer an interesting perspective on “natural” medicines.
The native Waroni people, we were told, invest all of their faith in single hereditary shaman. These shamans imbibe in hallucinogenic alkaloids (toxic chemicals produced by many tropical plants and the Dendrobitidae frogs) in order to see into the spirit world, where the causes of physical symptoms originate. One particular flowering plant—the angel’s trumpet—offers its user a three-day “trip”, during which time the pupils dilate so large that the user actually goes blind. With confidence, I’ll mention that one student from Moravia College attempted to use this flower as a marijuana substitute. He picked the flower, which is quite distinct, out of a high-altitude cloud forest and dried it in an oven. He then crushed it with a mortar and rolled up the powder into a cigarette. The students who bravely tried this cigarette reported a lucid and relaxed feeling, but no hallucinations. In fact, none of them were aware that the plant was supposed to cause three-days of blindness, juxtaposed insensibly with the phantom apparitions and geometrical distortions commonly associated with a trip. When the shaman prepare the same flower, they boil it for several days and drink the water. It’s likely the route of transmission used by the foolhardy Moravians simply failed to tap into the trumpet’s terrifying potential.
Alkaloids are not special compounds produced by human beings selecting for plants with more intense highs—they are merely defensive compounds (often called plant-secondary compounds). Caffeine and cocaine are alkaloids, as is quinine, the anti-malarial substance produced by shrubs of the genus Cinchona. Morphine is an alkaloid produced by poppy seeds (and is used as a painkiller and the derivative from the drugs heroine and opium). The cacti alkaloid peyote is a familiar hallucinogen in the American Southwest. Tropical morning glory fruits also produce hallucinogenic alkaloids in their seeds. The raison de entre of these compounds is to prevent herbivory. Human beings merely control their intake of these compounds to produce their stimulant or other-worldly effects.
The shaman also incorporate the capybara into their diagnostic toolkit. This largish cousin of the guinea pig is vigorously rubbed onto the ailed until it is crushed to death. The shaman then cut open the abdominal wall and read the entrails. This is interesting indeed, as entrail-reading is also common in ancient Greek and Roman traditions (there are references in Homer). Is there really enough variation in gut-morphology to support an inter-observer correlation of interpretation (never mind a correlation between interpretation and the real world)? I cannot help but imagine here a shaman going through this esoteric ceremony, cutting open the capybara and pronouncing his patient a mere hypochondriac. “I’m sorry,” he might say, “but the entrails do not lie.”
Does this methodology sound likely to produce any actual cures? That is, cures that could provide anything more than a psychosomatic response (i.e., the placebo effect)? I would think not, but apparently they have.
Jose pointed out many plants he believed to contain medicinal value. With the language barrier and the use of common-names, these descriptions are necessarily vague. However, it ought to give the reader an appreciation for the ubiquity of reputedly curative organisms in the tropics.
Bordering our bungalows we observed a red flower Jose claimed stimulated lactation in females. The common-names of trees with medicinal uses are usually very linear—thus, this red flower was called simply the breast-milk flower. Sometimes, a perfunctory “of the tropics” is tacked onto the end. Similarly, one day Jose picked a large leaf off an understory plant and took a bite of it. He offered it to me and I obliged. This was a sour-cane plant and it tasted like lemons. Jose claimed to have personally used this plant to relieve the pains of urination. Jose once picked up a mushroom called the “dead-finger fungus”. When the stem of this mushroom is squeezed, a clear substance comes out. Jose claimed that ear infections were treated with this fluid by simply dripping it directly into the ear canal.
Jose did not subscribe to all of the traditional wisdom of tropical cures, however. He admitted having been twice stung by a Conga (or bullet) ant, and only once administered with the natural ailment (which is produced from some species of vine), that both events were equally miserable. “I couldn’t sleep all night. My arm ached. It was terrible,” he said.
Some “cures” are easier to understand. For instance, the mandibles of army ants can be used to cauterize wounds. The ant is simply held up to the wound and encouraged to bite at either end, holding it together. When the rest of the body (including the formic-acid filled abdomen) is pinched off, these mandibles hold fast and keep the wound pinched shut. Similarly, the fruit of the Crucia tree produces a natural adhesive that can be used to close wounds.
It is interesting to note that while large food-processors use formic acid as a preservative, indigenous people do not. This acid can be isolated from the abdomen of ants (particularly the lemon-tree ant, see “Tending the Devil’s Gardens”). Is it possible that subsidence style agriculture and hunting practices prevent the need for hygienic food storage? On our way upriver on the Napo we observed some armed Waroni tribesmen on their way to hunt monkeys. Perhaps they harvest only that which they can eat. Perhaps they eat putrid carrion. Perhaps they’ve modernized, and possess refrigerators and ESPN. They were hunting with rifles, after all.
Unfortunately, I was unable to test any of these cures. The only ailments I suffered from in the tropical rainforest were chronic diabetes and Montezuma’s revenge. And while Jose pointed us towards some fruits that relieved constipation, he never pointed us to a plant that would relieve diarrhea.
The common denominator in all of these curative compounds is that they serve purposes in the plants that possess them. For instance, the dead-finger fungus probably contains an antibiotic to prevent the infection of its own tissues. The potent antibiotic pennicillen was discovered by accident in a fungus-infected bacteria culture. Similarly, it is not difficult to imagine the precursor to certain hormones are present in some plant tissues (for instance, the breast-milk flower).
June 1
Returning to Quito from Tiputini
Today we returned to Quito from TBS. Surprisingly, the journey took us roughly the same time. We traveled on the same boat with the same number of people but this time traveled up river. Moreover, the river had risen some three meters! Clearly the boatman was heavier on the throttle.
As we traveled the Tiputini and Napo rivers I had a chance to reflect on the differences between TBS and the La Suerte Biological Research Station in Northeast Costa Rica. I’d done a study on mantled howler monkeys at La Suerte. That study site had only 700 acres of rainforest, surrounded on all sides by banana, coconut, and pineapple plantations (pineapples were the major crop after the tsunami devastated plantations in Indonesia). Whenever I think of that study site I remember hiking through dense jungles, thinking that overhead I must be a near-invisible speck amongst an ocean of green, and then suddenly coming upon the border of the rainforest.
Tiputini, by comparison, is deep within the Yasuni National Park (9,820 square kilometers). The rainforest really is thick and mostly undisturbed (save for the oil companies, which defy measure). I’ve included a satellite photo of the Yasuni with a yellow pointer indicating TBS to give the reader an appreciation of the isolation and density of undisturbed vegetation.
While in Coca, a small town on the banks of the Napo River, we interacted with some domestic monkeys. These monkeys came in two species belonging to the same family (Cebines). Squirrel monkeys (genus Saimiri) and brown capuchins (genus Cebus) were found playing with one another. The squirrel monkey genus has an appropriate name. They look to me very much like little samurai warriors (complete with black hair pulled back tightly, a beard, and an orange robe).
These monkeys came right up to us, sometimes jumping right onto our backs. They would curiously eye our equipment, sometimes trying to look through our sunglasses or the wrong side of our camera lenses. Some of the squirrel monkeys were thieves, stealing a pack of fruits snacks right out of a Moravian’s backpack. Several students received bites from these monkeys and a few were crapped on—an inherent risk of handling primates.
I was singularly fortunate in this area. One of the brown capuchins jumped up onto my shoulder and began fingering through my hair. Frustrated that he could find no parasites (I suspect he wasn’t looking hard enough), he pulled my hair and started licking my scalp. Meanwhile, a squirrel monkey got hold of my sunglasses and wouldn’t let go. As none of them would let go, I picked up an apple from my bag and threw it to the ground. They quickly jumped off my back and started wrestling for it. One squirrel monkey fled with the apple and the others soon lost interest. Stephanie Daly was not so fortunate. The same monkeys crapped on her and then refused to let go of her hair. The capuchin seemed to get some peevish enjoyment out of pulling on her red locks and listening to her squeal.
Squirrel and capuchin monkeys often associate with one another in the wild. This relationship is thought to be slightly-parasitic commensalism. The big-brained capuchins possess manual dexteritiy—the ability to move each finger independently—and can wrest the sugary aryl from fruits with complicated coverings. Squirrel monkeys—much like the lesser-brained Atelines—lack manual dexterity. That is, their hands can assume one of two positions: open palm and closed fist. The squirrels are thought to follow the capuchins around so they can eat the disassembled fruits the capuchins discard.
During our stay at TBS the resident graduate students gave a discussion of their research projects on monkeys. One student, who as absent, was supposed to give a discussion on color vision and social interactions in squirrel monkeys. This would have been my favorite discussion as the patterns of inheritance of color vision in New World primates are both peculiar and well understood. In short, all male Platyrrhini are color blind (from our own trichromatic perspective). The human eye possesses three classes of color-sensitive cones: red, blue, and green. In Platyrrhini (pardon me, the flat-nosed primates of South and Central America), the genes that encode the red and green cones are found at the same locus on the X chromosome. The blue cone is found on an autosomal (or non sex-linked) chromosome. Thus, females (with two X chromosomes) can either be trichromatic or dichromatic. Male (with only one X chromosome) must be either red or green colorblind. Amongst Platrrhini, only howler monkeys (genus Alouatta) possess invariably trichromatic males.
As sensitivity to color may be useful in determining when certain fruits are ripe or flowers in bloom, one can imagine that trichromatic monkeys are at a considerable advantage. However, as all males are dichromatic, these monkeys probably possess social patterns where color-specialists (dichromats) and color-generalists (trichromats) work together to find patchy resources like fruits and flowers. In fact, I’m not sure if this graduate student meant to talk about this, but it would have made for an interesting research project.
After returning to Quito and eating dinner we spent the night on the town for drinking and dancing. The next morning we would hike up to the refuge camp of the world’s tallest active volcano.

The squirrel monkey is the one looking through my sunglasses, while the brown capuchin is propped up on my arm
.

Cotopaxi is the world’s tallest active volcano. The night previous, we were out enjoying the nightlife of Quito. For a reasonable two dollars cover charge at the most legitimate dive in town we were offered free screwdrivers, rum and cokes, and shots of tequila. Being shrewd consumers, we recognized this as an opportunity to save money by buying in bulk. The mixture of booze and altitude proved harrowing.
Cotopaxi is a stratovolcano, composed of distinct layers of lava and organic ash. We arrived after a 75 mile bus ride south from Quito. This volcano, compared to the basaltic ones on the Galapagos Islands, spews forth acidic magma (high in silica). Surrounding the volcano are massive black boulders. These enormous (some of them about 2 meters in diameter) stones were not cast into the air by an explosive eruption. Cotopaxi rises to around 5,900 meters (19,000 ft.) and is capped by a glacier. A glacier may seem out of place on the equator, but the air temperature reaches the freezing point due to the high altitude. Air expands as it rises, losing energy in the form of heat. This expanding air is both cooler and thinner than air at lower altitudes.
In 1877 Cotopaxi experienced a major eruption. The sudden release of pyroclastic ash (highly gaseous) melted much of the glacier. This, in turn, caused the mudslides that carried the enormous boulders down the volcano. Only about one thousand people were killed in this explosion as the surrounding area was thinly populated with indigenous tribes. Our guide informed us that the glacier appears to be receding, indicating that temperatures around the cone are increasing. Although instruments are installed to measure seismic activity, he admitted that by the time scientists could accurately forecast an eruption, evacuation would be an impossibility. The mudslides causes by the eruption will cut off the capital city of Quito from Gualaquil (and hence from the sea). According to our guide, we have every reason to suspect an eruption will occur within our lifetimes.
Our challenge for the day was to hike three hundred meters to the refuge camp (at 4,800 meters). Climbers spend the night at this camp and head out to the summit in the early morning. This is done to avoid navigating the glacier during the mid-day sun, when the ice at the glacier surface melts (the wet rocks are too slippery to climb). The incline was not particularly steep, nor the absolute distance great, yet all but six of us (Katie, Patrick, Stephanie M., Jen, Dr. Mackie, and myself) turned around after a few dozen paces.
I started the climb strong, trying to will myself into ignoring the thin air and my pounding headache. This was a poor strategy and I was soon overtaken by Katie and Patrick, who stuck with a more-or-less steady pace the entire way up. When I reached about half-way, I needed to sit down and catch my breath. I could see the even strata of red oxidized lava and darker volcanic ash along the summit of the volcano, as well as the glacier at the top. This break helped me almost none, as for the second half of the journey I had to stop and catch my breath after every five paces upwards. For those who are not acclimatized to high altitudes, the risks of pulmonary edema can be very real. Even deep breaths at high altitudes feel shallow. No vegetation grows at these high altitudes, and without vegetation no organism of a higher trophic level can make a living. While climbing to the top, looking up at the summit, I thought about Pliny the Elder. This ancient Roman naturalist died in his boots trying to get a better look at Mount Vesuvius as it erupted. The land we tread upon would soon be covered with mudslides, the air choked with toxic gas, and the temperature blisteringly hot. Yet now we were able to hike right up to the mouth of the sleeping dragon. As my breaths grew deeper, the back of my throat parched. When we finally made it to the top and reflected on the mass of our miserable hung-over comrades in the insect-sized bus below, we realized it was all worth it. At the refuge camp we were able to roll up snow balls and toss them at one another.
The hike down was considerably easier. While descending we spotted a condor in flight—a rare good omen, as the condors you can’t see are usually eating your dead body. These large birds are carrion feeders with special adaptations for living at high altitudes quite unlike those found in plants. While plants at high altitudes have thick leaves with stomata on the underside in order to prevent dehydration, Condors leave their head and necks unfeathered to facilitate dehydration. This presumably sterilizes portions of the bird most likely to be doused in the bacteria-rich fluids of dead flesh. It’s always interesting to see two different organisms adapting in opposite directions due to differences in life strategies (see “The Ways of Tropical Roots and Leaves”). Later, as we rode the bus across the high-land planes at the volcanoes base, we saw a team of some hundreds of wild horses gallop across the road. These are not just images, but real parts of a large and diverse world we live in. That’s all for today.

The following arrows depict—roughly—the route taken (including the boat passages on Guantanamera).




June 3rd
Today we arrived on San Cristobal. This was the first island Darwin visited on his 22 day tour of the archipelago. Darwin landed at playa corolla in 1831, about two kilometers the docks where we disembarked.
San Cristobal has a small-town atmosphere. The airport was out-of-commission during our stay and this contributed to the silence. Santa Cruz draws more tourists. Most of the natives of San Cristobal don’t care much for Santa Cruz. “It’s too loud. Too many people.” It’s clear some of this resentment is just envy over their more lucrative tourist business and their proximity to a functional airport (on Baltra).
As on Baltra, the island has a large population of sea lions (but not the smaller fur sea lions). On Baltra we observed sea lions passed out on benches and along stair cases like town drunks. The sea lions of San Cristobal are restricted more to the beaches—thanks in part to barriers erected to prevent them from wandering into town. The sea lions of San Cristobal (los lobos to the locals) were ornery but not overtly aggressive. Each sea lion has a personal bubble with a radius of about one meter. If you step inside, they may lunge at you, but won’t chase you for more than a few paces.
I will refer the reader to “Physiological Color Change in Galapagos Lava Lizards” for my observations and experiments on lava lizards and pass on any additional observations here. When Darwin arrived on San Cristobal (what he knew as “Chatham” island) there were both wild tortoises and land iguanas. The recent extinction of both of these reptiles is thought to result from introduced goats, pigs, and rats, which perform extremely well on the islands and ravage the nesting sites of native fauna. The decline in the tortoise population may also be due to their intense exploitation by pirates and whalers, who harvested these giants by the thousands.
After disembarking, we made our way to the Galapagos Institute for the Arts and Sciences (GIAS) for orientation. GIAS is a small community college offering associates degrees in tourism and environmental sciences. Though the college accommodates only thirty students at a time, it contains a dormitory wing. One cannot help but come to the conclusion, looking at GIAS and talking with the faculty, that USFQ uses this outpost to entertain foreign students, running the community college only to keep a good relationship with the locals and bring in some additional revenue. For instance, though the college offers degrees in environmental science, we talked to no students pursuing this degree, nor did we see any laboratory where they might perform experiments.
GIAS overlooks playa man, a public beach with white organic sand bordered on either side by large basaltic boulders. On these boulders I observed many yearling marine iguanas (about 25 cm long), which were almost impossible to capture. These iguanas are apathetic to the large rock crabs that flee anything that moves, oftentimes leaping from boulder to boulder with surprising agility. More than one student commented “they are just like spiders!” I found, as Darwin noted before me, that marine iguanas can not be chased into the water. This makes them only a little easier to capture, as the wet rocks are extremely slippery. The juvenile marine iguanas were observed eating algae off the rocks, but were not seen in the water.
I should note here that the Galapagos National Park absolutely prohibits handling animals. I consciously and repeatedly ignored this rule—I’ll let the reader judge the ethics. While no animal was hurt by my handling, there are likely very good reasons for the park’s rules. My penchant for taking “hands-on” learning completely literally led to the creation of another long-running inside-joke. One day I half-seriously suggested that all biologists be exempt from the normal laws and procedures of national parks.
“How would they know you were a biologist?” asked an amused Megan Bales.
“I would have a badge,” I responded. “Any time a park official reproached me, I’d just flash it and exclaim: ‘It’s okay, I’m biologist!’” This motto was repeated hundreds of times while touring the archipelago.
Thus, to the reader who finds my actions inappropriate, I would like to offer this singular pre-emptive rebuttal.
It’s okay. I’m a biologist.
Playa man is also home to a large colony of bachelor-male sea lions. There are some females with suckling pups there as well, but males predominate (see “Sea Lion Project”). The large male sea lions are called “Machos”. Sex-determination is easy in machos as they possess a bulbous lump on their forehead. However, smaller males have no lump and can only be sexed by sneaking a peak at their genitals. It really is rather amazing that even the largest males have penises scarcely bigger than the nipple of a mid-sized female. When sea lions stand erect on their front fins the skin under their stunted tails looks like testicles, even in females. Males have a deeper, guttural grunt but are generally not more protective of their personal space. Machos who possess harems offer an exception to this rule. These large males spend all of their time patrolling the beach and may be provoked more easily than bachelor males.
Orientation was likely interesting, but I was too busy listening to the hilarious belching and barking of the sea lions. The pups make squealing noises which sound so adorably pathetic that they are inevitably followed by a chorus of human “awwwwwws!” These little pups spend most of their time on land trying to suckle their mothers. They can actually be quite aggressive, particularly when juveniles approach their mother. Surprisingly, they are largely successful in chasing off larger sea lions.
There are several palm trees in front of GIAS. These trees, which are common on oceanic islands, had to be introduced to the Galapagos archipelago. This is really quite surprising, as introduced palms have had no problem establishing themselves. The palm fronds in front of GIAS were covered in tiny (less than 1 cm in diameter) barnacles.
Opuntia cacti are common, particularly in the large arid zones that dominate the island (particularly on the north side, where the volcanic crater casts its rain shadow). We did not see any mangrove forests along the coasts near the town or university. These salt-tolerant plants come in three variety on the islands—green, orange, and black. Their stilted roots extend right into the water. The non-succulent leaves of plants growing on the islands are small and orientated perpendicular to the group (so that sunlight strikes them at an oblique angle). These are adaptations to avoid desiccation, as opposed the water shedding adaptations of tropical leaves. Most of the flowers we observed were small (to avoid drying out) and yellow. The prevalence of yellow flowers follows from the paucity of available pollinators. One species of carpenter bee specialized to pollinate yellow flowers on the mainland handles a majority of the pollinating in the Galapagos Islands. The plants themselves must have some adaptations to avoid inter-species pollination.
The most common land-birds observed were ground finches (genus Geospezia), yellow warblers, and an endemic mocking bird. The most common reptile observed was the lava lizard Microlophus buittatus, but at least five other species of gecko (including the endemic leaf gecko) were also observed. Besides sea-lions, the only other mammal observed were domestic dogs and cats. Some of the domestic cats were pouncing on the lava lizards.
San Cristobal is an eastern island, far from the hot spot sitting under the active volcanoes of Isabella. As the crater has long been inactive, the most recent major disturbances on the islands have been due to the increase of the human population, a major oil spill off the coast in 2001, and recent El Nino/La Nina events. While we were on the islands they were said to be in a “mild El Nino”.
When orientation wrapped up we gathered around the front of GIAS and waited for our host-families to pick us up. One by one each student left with their host-moms. The custom on the islands (which was never observed on the mainland) is to kiss the women on both cheeks. The men shake hands. Each student left in a taxi pick-up truck, which cost only $1 to go anywhere in town. My host mom was the last to show up (through the fault of GIAS, not her own negligence). Her name is Patti Iturraole, a petite woman somewhere in her forties (I was not bold enough to be scientifically precise in this measure) with two sons, one a student at the USFQ and the other a seven-year old elementary schooler named Armaritto. Patti lives in what is jokingly referred to as the Barrio (or the ghetto) immediately adjacent to the airport. I would learn later that her neighborhood was considered “bad”. In fact, it was “bad” by no absolute measure and many neighborhoods
in Champaign, IL could be called much worse.
Patti lives in a stilted bamboo house with a green roof. The inside is full of arts and crafts, musical instruments, and books of art prints. I noted with approval a worn down copy of The Origin of Species on her mantle. Her husband David was in Quito at the time “on business,” though with my limited Spanish skills I was unable to determine what business she meant. I went to sleep early that night and readied myself for my first full day on the islands.

Can you see the finch?June 4
Today was not an eventful day. After a light breakfast with Patti and Armarrito (two eggs, a bowl of fruit, a stiff cup of coffee and multiple denials that I wanted more bread) I prepared to leave for GIAS. Lectures were to be at 9 am and I didn’t want to be late. Patti sympathized and told me I could use David’s bicycle while he was out of town. I obliged and rode off into town while Patti prepared Armarrito for school. I learned she works at the cafeteria of Armarrito’s school and knows all the teachers. The boy can get away with nothing.
David’s bike was a rusty nine-gear number lodged permanently in third. Patti’s house is a little over two kilometers to GIAS and I was able to pass everyone up on the way to school. “Where did you get the bike?” they shouted. “They’re handing them out!” I responded. I will not simply summarize the lectures, but follow the same pattern I’ve been using all along and use the material as background information where it is relevant.
After the lecture and lunch we hung out at playa man for a while. Many fishing boats are anchored off the shore (outside of the intertidal zone). We visited the interpretation center and read up on the founding of the islands, the theory of evolution, and volcanology.
Later as I walked back to my home-stay, I realized two things. First, I had left my bicycle at GIAS, and second, I had no idea where I was. Luckily I was approached randomly by a woman named Beatrice who wanted to know if I was “Steven, the volunteer from the Darwin Station.”
“No,” I said. “Sorry.”
She waved her hand dismissively. “Don’t worry about it. You don’t look like Steven anyways. He’s supposed to be Asian.”
“Oh?” I said.
“Do you know where you’re going?” she said.
“No,” I said. “Do you know Patti Iturraole?”
“Is she a big woman?” she said.
“No,” I said.
“Maybe I know her,” she said. “Come with me.”
I walked with Beatrice, who was a particularly bizarre woman. I asked her where she learned to speak English.
“In the United States. I lived there for twenty years,” she said.
“What did you do in the United States?” I said.
“I taught people to speak English!” she said. Suddenly she realized this had not been obvious and apologized. As we walked she told me all about her problems.
Beatrice owned a dairy farm about an hour out of town. She was a widow and she inherited the farm from her husband, who was from the states. Her son went to school to become a mechanical engineer and she had hoped he’d return to the island to take over the farm. He had other plans.
“He did come back,” she said, “but all of the things he told the workers were ignored as soon as he left.”
“That’s too bad,” I said.
Beatrice was upset. She was convinced her farm needed modernization, but lacked the technical know-how to make it happen. She tried to cross breed her wild cattle with a domestic breed from the mainland. She was convinced that the progeny were worse off than the wild breed she was trying to improve.
“Do you know anything about embryo transfer?” she said.
“Ahhh….”
“They say you can get fifty cattle from one. Fifty cattle! Imagine that. How is that possible?” she said. After all, I was a biologist, and ought to know that sort of thing. I told her I didn’t know that it was possible, and suggested she talk to Dr. Mackie.
“I don’t know Dr. Mackie,” she said.
“He’s Diego’s friend,” I said. “From the University of Illinois. My school.”
“Diego!” she said. She knew Diego. She resolved to come meet Dr. Mackie.
After trying unsuccessfully to track down Patti Iturraole, recruiting Kristen’s host-mom in the search, we finally all decided to go back to GIAS and sort this mess out. Kristen’s host-mom told me if I ever wanted to come back to San Cristobal, I could stay at her house.
“Thank you,” I said.
“He won’t be back here for five or six years at the soonest!” boomed Beatrice, whose over the top candor never failed to impress.
When we returned to GIAS, Beatrice and Dr. Mackie discussed her dairy farm. She repeated a theme dear to her heart: “The University ought to prioritize cultivating the land. That is the most important thing.” Even on the mainland, the USFQ provides no school of agriculture. Most people in the life sciences view the native peoples of the Galapagos as an unfortunate reality—a reality that will destroy everything about the islands that people admired most: its virgin land and endemic flora and fauna. Thus there is little sympathy in academic circles for Galapagos farmers and fishermen.
Dr. Mackie agreed to go and take a look at Beatrice’s farm, maybe providing some technical advice. Beatrice looked me in the eyes.
“Things happen for a reason,” she told me. “And when they do, you have to run with it.”
Unfortunately, I knew all too well how she meant it. I had come into her life to segue the provincial dark ages of her destitute cattle farm into a modern, genetically envelope-pushing dairy empire. This is the magic-wand understanding of science—the idea that advanced technology can be used to bypass the need for experience and hard work.
Later that night we met up at the most happening bar on San Cristobal: the Aricife de Coral. If I know the other students well (and I do) the details of this karaoke hang-out have been described thoroughly. Allow me only to mention that I sung perhaps the most awesome cover of Survivor’s “Eye of the Tiger” ears are fit to hear (and provided several encores, though the audience was too shy to ask for them). Also, and slightly more objectively, I observed a common phenomenon amongst students transplanted into a foreign culture: They inevitably cling onto the most corny piece of Americana they can find. A karaoke ensemble of song and dance numbers from the musical “Grease” filled our aberrant need for something American as apple pie.




June 5
Today was unique in several respects. It was the day of our first visit to playa corolla, the site of Darwin’s landing some one-hundred and seventy years previous. The beach of playa corolla is larger than playa man and with fewer sea lions. The light tower at the north end is surrounded by the black basaltic boulders which seem to border every shoreline in the Galapagos. On these boulders we saw many large marine iguanas.
Large marine iguanas often appear fat. They congregate in large groups (around twelve individuals in an area of two square meters) of males and females. The males can be distinguished from the females by their dorsal crest. Marine iguanas have a broad snout, which is usually caked in salt. Every few seconds the iguanas eject salt from their nostrils. While this is supposed to be a sign of agitation, they do it continuously even when observed at a distance. This was the first day that I handled a marine iguana and I made a few mistakes.
As I approached the iguanas I felt a vague unease. I was familiar with their reputation for phlegmatic behavior but their bold habit of standing their ground and eyeing me indifferently forced me to acknowledge the risk that, if I grabbed one, the rest would simply attack me in a group and bite and claw me painfully. This risk does not exist, but a lizard larger than a meter long tends to encourage worse-scenario thinking in the uninitiated.
As I approached closer, many of the iguanas retreated. I was able to get much closer to the large adults than to the yearlings. It seems likely that their phlegmatic character increases with size. As I approached closer still, I reached my hand out and grabbed at the tail of a large male. He responded by immediately attempting to retreat. Many lizards (particularly iguanas) use tail-shedding as a defense mechanism. However, neither marine nor land iguanas use this strategy. In marine iguanas at least this makes some sense—a marine iguana without a tail would be unable to swim (and may be as good as dead as a result). I can think of no reason why land iguanas don’t shed their tails.
Not only do marine iguanas not shed their tails, but they don’t use them as whips either. I’ve handled many maladjusted green iguanas in my time and I can attest to the utility of the tail as a defense mechanism. However, this iguana neither attempted to whip me as I got close nor shed its tail as I held onto it. Instead, it tried to get a better hold of the rocks and pull itself from my grasp. Convinced that he wasn’t going to turn around a bite me, I went in for the neck-grab. I put my hand around his neck and lifted the large iguana into the air. In this position the iguanas do possess a natural defense. With his hind limb he reached back across my forearm and started scratching me with his large black claws. While I was able to get a better hold of him and prevent his doing this, the cuts he inflicted actually drew some blood across my arm.
In keeping with my experience with most of the reptiles I handled in Ecuador and elsewhere, these iguanas became more docile the longer I held onto them. This particular male was content to sit on my lap as I inspected him. Some lizards will open their mouths in protest while being handled, but I believed I could have probably put a leash around the neck of this particular iguana and convinced it to walk home with me. It’s fortunate these gentle beasts do not share a habitat with introduced animals as they would never survive. After some time looking at the iguana I set him down on the rocks and watched him take a few quick steps and then settle down on a rock.
That same day we went snorkeling off playa corolla. This is only possible at high tide due to the abundant sharp edged boulders along the entrance to the water. These boulders are treacherous if one tries to walk over them. They must be swam over and so there must be enough water over their tops to clear them and get into the intertidal zone. Marine life can be seen immediately in the form of zebra fish. These cryptic fish change color rapidly (this is called physiological color change, and it is discussed in my lengthy discussion of the phenomena in lava lizards). The most abundant living thing is certainly the pencil urchins. The pencil-like extensions of these creatures wash up onto the beach in abundance and they litter the ocean bottom (they look vaguely like mines, inasmuch as they are a spherical core with finger-like projections).
We saw many other tropical fish which I did not recognize. I saw one octopus with a similar color change mechanism as the zebra fish, only more impressive. This little mollusk swam from the rocks to the white sand with a wave-like contraction of colors instantaneously in sync with the color of its surrounding gradient. Octopi are commonly referred to as “smart”. An appreciation of the physiological color change in octopi is an appreciation for intelligence inasmuch as it requires advanced neurological machinery to see the colors and patterns of a gradient and memorize it on the surface of one’s skin through precise contractions of pigmented muscle cells. One can be sure that nerves are involved because the changes are too rapid to be explained by a chemical pathway (electric signals travel much faster than chemical signals).
Water carries sound waves better than air. While I was snorkeling I could hear a sort of rapid crackling noise (like the sound of Rice Crispies). I’m not sure what caused this sound, but I’ve heard from a few people who have snorkeled off the Great Barrier Reef in Australia that fish eating at coral cause a similar noise, which can get quite loud when enough are feasting. There are only two types of coral in the waters of the Galapagos archipelago—white coral and white-brain coral. While the nutrient rich upwellings caused by the Humboldt current from the south provide form a rich diversity of marine life most coral require warmer water to survive. Parrot fish are the principle grazers on these corals and most of the white sand of organic beaches is formed by the physical break-down of corals as they pass through the alimentary canals of these fishes. It’s very liberating merely to allow yourself to float passively over an entire marine ecosystem, free to observe all of its intricacies from a birds-eye view.
June 6
La Lobriea and Puerto Chino
Today we conducted a marine animal survey at la lobriea and visited the beaches of puerto chino. The normal strict rules of the national park were treated with benign neglect as we picked up all matter of marine life we could find along the rocky shores. Hermit and rock crabs, echinoderms, sea slugs, and some other critters were rounded up in plastic collection bins and turned over to a USFQ graduate student for identification. By far the most interesting thing we saw that day was a red polycheate. These marine flat worms are poisonous—a fact I’m proud to report I observed before our graduate student told us about it. I knew the worms were poisonous because they’re so colorful. This is a good rule of thumb for those students like me infected with the Steve Irwin bug—if it’s colorful, don’t touch it!
The beaches of Puerto Chino were the most beautiful on the island. We spent some time riding waves. This was the first day that I attempted an experiment on lava lizards. I caught one along the rocks and placed it on the cool wet sand. I hoped to observe some color change associated with the change in gradients. Perhaps due to my searching eye, I saw the color change I was looking for and decided on my research project (see “Physiological Color Change in Galapagos Lava Lizards”).
Today was interesting for another reason altogether. My conversations with Patti had been progressing in complexity steadily since I first met her. I brought her a gift—a large picture-book of the city of Chicago at night—and we discussed it at length. She told me her sister lived in Texas, in the city of Chicago. I showed her a map and explained the relative positions of Texas and Chicago. I asked her how many states she figured the U.S. contained. Her answer was twenty. She asked me if Illinois had a tropical climate. I laughed, as this was one step more absurd than the notion that Texas is a district of Chicago.
With me as her English teacher Patti was at a decided disadvantage. I was introduced to her brother and his “husband”. Only his “husband” was his wife. At our first meeting, Patti had searched for the English equivalent to espousa (or spouse). I told her “husband”. For the remainder of the trip I tried to sell her on “wife” as the female equivalent, but she held out strong in favor of “husband” for all spouses. Thus, I was introduced to several female “husbands” who looked at me confusedly as I chuckled.
Finally I got up the courage to ask Patti what her husband David was doing in Quito. The answer was confusing and the only word I thought I recognized I knew must have been a mistake. She kept saying “muppets”. Finally I said “What means ‘muppets’?” She laughed and took out a thick scrap book. Its contents were priceless.
David is a puppeteer. He was in Quito for an international exposition of different puppeteering styles. He got his start as a theatre student in Argentina. Patti showed me photos from his teenage years, when he performed in a sort of vaudeville act with some Rocky Horror Picture Show style drag queens mixed with elaborate costumes, historical reenactments, religious satire and pure slapstick. David was Don Quixote and Sancho Panza, twice Hamlet and once the clown, sometimes kings but more often than not somber and irreproachable clergymen. I learned with some amusement that David even performed a puppet show about Charles Darwin. Luckily, I would have a chance to meet him.
Later that night the town was holding a festival near the docks. The locals were celebrating a new piece of environmental legislation relating to the Galapagos Marine Reserve and they called out some Ecuadorian pop signers to draw a crowd. This festival was as toned down as any I’ve ever been to. When some of the locals were asked why they weren’t dancing, they answered simply “Because it’s a weekday.”
Everyone had to be at work in the morning. What was there to dance about?

June 7
El Junco and La Galapaguera
Today we went to the freshwater lake El Junco at the crater of San Cristobal. We also visited the Galapagera tortoise-breeding station. While we took the bus from the low arid-zones up to the crater we had a chance to observe some of the distinct vegetation zones.
The distinct vegetative zones are created by differences in rainfall along an altitude gradient. Along the shores there is also a small littoral zone where salt-water mangroves grow (though not around Wreck Bay, as mentioned earlier). The littoral zone quickly gives way to the arid zone, which is rich in optunia cacti and palo santo (Bursera graveolens). Many times I stood facing a thick brush of palo santo. During our stay the islands had entered the beginning of the dry garua season and none of the palo santos possessed leaves. However, when the wind catches the wood of these trees a pleasant fragrance fills the air.
The arid zones (80-120 meter elevation) are the largest and the centers of island endemism. This is in part due to the fact that cash crops grown on the Galapagos are planted in the highland Scelasia and Miconia zones (from an altitude of 200-1,000 meters above sea level). Inevitably, when I close my eyes and try and conjure up an image of the islands I think of the dry arid-zone, a land iguana digging a burrow, a saddle-backed tortoise reaching up to eat at the succulent leaves of an opuntia, and a large beaked ground finch hopping around in the shade.
The islands are considerably more diverse than this. As the bus drove through the transition zone into the scalesia zone (200-400 meters) I was somewhat let down. The scalesia forests were described as a dense tropical jungle. The trees were more patchy than I expected and nowhere could I see the beautiful epiphytes of the tropical rainforest. In their place hung masses of brown moss and one could hardly see the white-flowers underneath. The brown mosses, or liverworts, fall from the scalesia trees and carpet the ground. This is called the brown-zone.
The next “zone” commonly cited in books on the islands simply does not exist along the incline of incline of the San Joaquin crater. Miconia trees are monocotyledons with parraellel leaf veins. These trees require abundant rainfall and exist only on the windward side of volcanic craters along the archipelago. However, on San Cristobal introduced guava trees, banana plantations, and raspberries have ousted the miconia. I can only for certain say that I saw half-a-dozen of these trees along our journey to the highlands.
When we arrived at laguna el junco (at around 700 meters above sea level), we’d entered the fern and grass zone. El junco is the only freshwater lake on the islands. Its diameter is 260 meters and its depth is 6 meters. We observed some frigate birds, but were unable to determine from a distance whether they were great or magnificent (This was not a debate about their majesty, but a specific taxonomic argument. Great and magnifiscent frigate birds are different species. We would often joke that the evolution of frigate birds proceeded from an insensible graduation from the lowly to the magnificent frigate, with the it-has-its-moments frigate as a perfect intermediate.)
The uncertainty over the species was the result of our distance from these interesting aves. These large birds have white-breasts and black feathers along their back. The beak is curved downward at the end (like a predatory bird), the wingspan is as large as that of an albatross, and the males possess a red leather pouch under their beaks that they inflate in order to attract mates. The magnificent frigate bird differs only in having a purple sheen along its black feathers. Female magnificent frigates also possess a black triangle on the white feathers of its throat. The most conspicuous differences between these birds is their feeding zones. Great frigate birds are pelagic—they feed far offshore. Magnificent frigates are inshore feeders (like the blue-footed boobies).
However, as we were offshore and el junco contains no fish, we could not observe any nesting or feeding behavior. Instead, these birds appear to use the lake to wash the salt off their feathers. While we could see the red patches under the male beaks, none of these patches were inflated. Our guide informed us that though these patches undoubtedly help the males attract mates, the most successful males are not always those with the largest patches. Rather, the males who build the largest nests attract the most females. Thus, we joked that the females knew that the red-pouch was just “an extension of the males nest.”
A few years previous, Diego had dived to the bottom of this lake to collect sediment deposits. These deposits can be removed in cydrical cores and subjected to radiometric dating techniques. One would expect that San Cristobal have considerably older deposits than Santa Cruz (which should have older deposits than Isabella). Moreover, these differences in the sediment ages combined with the distances between each volcanic crater ought to yield a rate of drift from the volcanic hot-spot that mirrors known rates of subduction under the continental plate of South America. After discussing this idea with the guide he admitted that he wasn’t sure whether anyone had bothered to measure the shifting of tectonic plates through this independent measure.
As el junco provided an area where frigate birds congregated for the common purpose of bathing, one can’t help but wonder what these birds do on other islands that lack freshwater lakes. Do the frigatebirds merely get along with saltier feathers or do they find some other ingenious solution to this problem?
After touring around el junco we got back onto the bus and headed for the tortoise-breeding station. We sited more mockingbirds along the highlands than in the arid-zones. La Galapaguera is a station further west from el junco where saddle backed tortoises are breed in captivity. These tortoises possess a raises carapace in front for feeding on vegetation—from optunia cacti to poison apples. As we walked along the trails of Galapaguera we came upon a tortoise making his way to a watering hole. As we approached, he drew into his shell. The act of pulling its head and legs into the shell causes air to be released, forming a hissing sound. Thus, the tortoises do not actually leer at human beings, hissing aggressively. They merely defensively tuck into their shells.
However, these tortoises do make noises on other occasions. According to our guide, the males make noises as they battle one another during mating season. Similarly, while having sex the males grunt and moan. We heard of this several times, and each person who witnessed it laughed while telling us. I imagine this is either an hilarious display or else the most well-known lie told to gullible tourists.
Several large tortoises (about one meter from head to tail) were observed drinking water and almost entirely submerged in the drinking pool. Tortoises love water. This observation saddened me, as they are also capable of going without it for years on end, turned upside-down in the hold of a pirating ship. Are these tortoises great stoics, or was their pain and longing for water the sole occupation of their tortured minds during their long-journeys over the sea (ended in the boiling pot of a hungry buccaneer).
We had a chance to see some of the yearling tortoises as well. Dr. Mackie commented on the growth of one small tortoise named “Genisis”. Genisis had just turned two years old and Dr. Mackie was able to comment on his growth (which was considerable). Our guide told us that the characteristic differences between the large dome-shaped tortoise of the high lands and the smaller saddle-backs of the arid zones can only be seen sometime after the tortoise reaches maturity. This is interesting in terms of the embryonic laws of Ernst von Baer, who proposed that those qualities general to a group are expressed earlier in development than qualities specific to a species. Does the homogeny of form of these developing tortoises tell us anything about the routes and rates of evolution? I have no idea. I suspect yes it does.
A tortoise reaches sexual maturity at age twenty and can live to be two hundred years old. As males are not involved in the upbringing of young tortoises, they are presumably free to copulate with multiple females during the mating season. The mating season takes place during the wet season (December to May) and each female can lie anywhere from twelve to fifteen eggs. Thus, one can imagine a robust and virile male tortoise could sire some thousands of offspring throughout its long life (two copulations per mating season for a two-hundred year tortoise could mean 5,400 offspring). Moreover, a male tortoise might compete with a great-great-great-great-great-great grandson for a mate! Might the long life, seasonal mating, and relatively early sexual maturity of these marvelous tortoises have paved the way for rapid population increase? Even rare fortuitous mutations could become fixed in a population with tortoises who re-introduce them into the gene-pool thousands of times. Here the tortoise may rival the hare in terms of pure fecundity.
The tortoise carapace develops from the rib cages of the developing embryo and exhibit some discrete diamond shaped portions along the surface. These sections have growth-rings similar to those of a tree. Trees only exhibit growth rings in temperate forests (where they grow in discrete bursts, entering a period of quiescence during the cold season). Tortoises presumably also grow discontinuously (this is true only if the rings really are reliable indicators of age, which is often disputed).
A truly remarkable day I will not soon forget.
June 9-13
Sea-lion project

Dr. Mackie assigned our class a project on sea-lions. This project would involve measuring the group composition (in terms of age/sex demographics) and observing behaviors. The groups would split up on different beaches (Figure 1). Observation periods were split up into high tide, low tide, and bedtime (6:00pm) (see Figure 2). Monday (6/10) was skipped due to our visit to Kicker Rock and Isla Lobos.
Playa Mann
Playa Corolla
Town Plaza
Lindsey
Stephanie M.
Kristen
Figure 1 (above). Team composition at each observation site.Brian
Eddie
Patrick
Yukari
Jennifer
Mike
Megan
Stephanie D.
Katie


Day
Low Tide
High Tide
Saturday (6/09)
Sunday (6/10)
Tuesday (6/12)
Wednesday (6/13)
9:01 am
10:01 am
6:27 pm
12:52 pm
3:32 pm
4:34 pm
11:57 am
6:46 am
Figure 2 (above). Dates and times of observation vs. the tide


Our data for the group compositions (with both total number and percentage) are listed in Figure 3 on the following page. I will here make some general observations about the differences between the compositions made at the other beaches and the behavior of our sea lions.
Playa Mann houses a bachelor community of males (ranging from 12-38 members) and a few females. With the exception of our first two observation days, when the sex ratio of adult sea lions actually favored females, on most days we observed more males than females (peaking at 90% males on 6/10). These males live in relative harmony with one another, though the designation of 6 pm as the “bedtime” count was singularly misleading. The males spend all night fighting with one another—not drawing blood, but chest bouncing and barking aggressively. Dr. Mackie attested to this fact as he was sleeping at GIAS, right outside Playa Mann.
Originally I had planned to use a focal-animal observation technique. For the first few days everyone in the group selected an animal (we split it up so we all had different demographics—for instance I watched a pup while Kristen observed a Macho). However, this technique failed to yield any data we could use to answer a specific research question. Pups spent all of their time suckling. The rest of the demographics spent all of their time napping on land and few behaviors could be observed (except yawning, scratching, and rolling over). The problem with this method is we were unable to follow the sea lions out to sea. Using this method to watch sea lions only on land is like watching monkeys only during nap time. Beach behavior excludes feeding, play, and copulation—in short, the most interesting sea lion behaviors one can observe.
However, we were able to make a few interesting observations. First, the sea lions on Playa Mann were more aggressive than at Corolla and Plaza. As these sea lions also constitute a bachelor colony this was not the expected result. Bachelor males are supposed to be more phlegmatic—almost on vacation from the rigors of unremitting copulation and harem defending he will soon return to. The sea lions seemed to have a particular reversion for me. As this could not possibly have anything to do with my personality, I can only suppose that my greater size put them into a defensive mood. As to the phenomenon of aggressiveness in particular, we concluded that harassment from humans is probably greatest at Playa Mann. Little kids were often observed kicking sand and throwing bales of water onto the sea lions. This observation held true wherever we went—the sea lions most habituated to people were the most aggressive.
Comparatively, the sea lions at Playa Corolla and Town Plaza were much more approachable. Diego told us that they had just recently built a large barrier around the beach of Town Plaza, as the sea lions had been crossing the street and entering the town. Mike, who spent his time measuring the distance at which sea lions will illicit an aggressive response, was only once chased at Town Plaza. The sea lion that gave chase was the resident Macho. Town Plaza housed a harem of females. When Mike approached the Macho around the area where the waves break, he was chased onto the beach. To contrast, I was chased all around Playa Mann by males and females alike.
The Town Plaza group also observed large juvenile sea lions suckling. Whereas we only observed pups suckling (pups being defined as sea lions less than a meter from head to tailfin), the juveniles suckling at Town Plaza were in some cases just as large as the lactating females. I’ll come back to this observation later when I discuss our visit to Genovesa Island, where I observed the same thing.
Sea lion pups do not go out fishing with their moms. Anytime we observed a discrepancy between the number of females and the number of pups this was probably because the females were out fishing. Sea lions gorge themselves on sardines and the females must remain well fed in order to their pups for as long as two years. The mother sea lions recognize their pups distinctive cry. Pups were not observed attempting to suckle from more than one female. While be suckled, the mothers often get up and relocate, sometimes covering their sore nipples and gently pushing their pups away. These efforts are in vain, for the pups will inevitably suckle for as long as they please (which is almost permanently).
Some sea lions were easy to recognize. Originally, I fancied myself a particularly photographic memorizer, and I named all the lions. The big machos were Christened in honor of famous movie gangsters—Vito, Clamenza, Barzini, Tesio, Pesci, Scarface, and Moe Green (whose coat always seemed to be stained green). However, these names soon became jumbled and only a few sea were distinguishable from one another. One female possessed a scar in the shape of a bowtie (so we called her “bowtie”). Another female had a circular scar around her neck (so we called her “collar”). One petite female, with bottled up aggression that belied her small stature, chased me across half of Playa Mann. I named her for a girl I once knew.
I’d like to note here one additional observation on the expectation that bachelor groups should be the most docile. Bachelor groups are said to occupy the lowest quality beaches. Might a low-quality beach be one filled with mischievous apes? If people make a beach low quality and upset sea lions, perhaps our expectation ought to be that sea lions in highly populated areas should be the most dangerous in bachelor troops! This observation also holds true for lava lizards and marine iguanas. Vigilance on the part of all living things on the islands is greatest where people are the most densely populated.



Date and Time
Males
%
Females
%
Juveniles
%
Pups
%
6/9/2007
9:00
19
35.8
23
43.4
9
17
2
3.7
6/9/2007 15:30
12
37.5
13
40.6
4
12.5
1
3.1
6/9/2007 18:00
29
78.4
6
16.2
1
2.7
1
2.7
6/10/2007 10:00
15
50
8
26.7
6
20
1
3.3
6/10/2007 16:30
33
86.8
1
2.6
1
2.6
3
7.9
6/10/2007 18:00
37
90.2
3
7.3
1
2.4
0
0
6/12/2007 11:30
18
85.7
2
9.5
1
4.8
0
0
6/12/2007 18:00
38
84.4
2
4.4
3
6.7
2
4.4
6/13/2007 7:30
37
75.5
5
10.2
5
10.2
2
4.1
6/13/2007 11:30
15
71.4
3
14.3
2
9.5
1
4.8

Physiological Color Change in the Galapagos Lava Lizard Microlophus biuttatus on San Cristobal Island

“There is one small lizard belonging to a South American genus…”
--all Charles Darwin ever said about Galapagos lava lizards

Figure 1. A lava lizard on Baltra Island.
I. Introduction and Background
Setting foot on the arid landscape of Baltra island, looking around at the abundant apuntia cacti and the yellow-orange basalt cooking in the sun, my first thought was “where are the reptiles?” Of all the fauna of the Galapagos, reptiles excited me most—the giant dome-shaped and saddle-backed tortoises, the land and marine iguanas, and the little lava lizards scampering across lava tubes. With what little free-time I had at the airport, I wandered into the desert to look for some interesting specimens.
Figure 1. A lava lizard on Baltra Island just outside the airport Lava lizards immediately caught my attention (Figure 1). These little (less than 25 centimeters) lizards belong to the endemic sub-genus Microlophus, with seven species on seven different islands. The lizards, sprawled out in the noon-day soon, allowed me to approach to within a few paces before darting off. Often, as I approached, the males (identified by their dorsal crest) would start doing “push-ups”. Unlike the head-bobbing displays in iguanas and anoles, the lava lizard uses its forelimbs to raise and lower its torso. Push-ups serve as both territorial displays to other males and solicitation to females. Mating, as it has been described to me, involves the female encroaching on the male territory, being seized forcibly in the male’s mouth, and carried off into the crevice of a rock. Here, they copulate safe from predators. Afterwards, the male returns immediately to its perch and tries again.
It was quite amusing to see the lava lizards directing a territorial display at me, while I dwarfed the size of its largest predators (which include snakes, hawks, owls, herons, mockingbirds and introduced dogs and cats). This is a great example of insular naivety, or the peculiar stupefying effect of long isolation on an island with low mortality by predation (insular dwarfism and gigantism, by contrast, describe the evolutionary increases and decreases in size in the lineage of an island colonist). This same concept explains the approachability of the land and marine iguanas.
I tried several times to capture these lizards, which are spread out along almost every rock surface. The easiest way to handle a land or marine iguana is to grab hold of the tail with one hand and then just behind the head with the other. This same method does not work well with the smaller lava lizards, which possess the ability to drop their tails in moments of danger. Many lava lizards had scars and large rings around their tails at the previous site of auto-amputation. Instead of grabbing for the tail, the entire body needs to be flattened (albeit gently) against a hard surface with one hand and scooped up carefully with the other. Surprisingly, these naïve lizards proved spree. A failed attempt would excite the lizard into a bout of terrified retreat, oftentimes clumsily running into rocks and other barriers.
After leaving Baltra and arriving at San Cristobal I noticed a different species of lava lizard (Microlophus buittatus). These lizards, which also performed the push-up display, were extremely abundant. The males are distinct from the females in size, coloration, and the possession of a dorsal crest (Figure 2). Looking at the lizard with a birds-eye view, the dorsal crest is a thin red stripe bordered by alternating thick black and white stripes (about 1.5-2.0 centimeters wide). Where the sides meet the ventral surface, the lizard’s scales have a yellowish hue, cut into by vertical black stripes. The females, by comparison, are smaller and lighter in color. The scales are yellow and the ventral surface is white with red borders. Likewise, females have red coloration underneath their jaws (while also present in some males, this coloration is much duller and less pronounced).
As the rest of the students walked towards GAIS, I fell behind and watched for lava lizards. Both sexes appeared to vary in coloration. Some of the males were jet-black between their white stripes, while others had white splotches along their black stripes. Those lizards with jet-black stripes always appeared to have a red dorsal stripe, while those with white splotches possessed a white dorsal stripe. Likewise, the females were not uniformly colored—some appeared much lighter than others. The differences in the lizards’ coloration appeared to mirror the coloration of their gradient. I shared these observations with Dr. Mackie, who wondered if separate varieties of M. buittatus were specialized for life on different gradients. The white organic beaches are formed from the break-down of corrals (mostly after being passed through parrot fish). Black basaltic rock is the most common gradient, but red basalt with a high concentration of oxidized irons and yellow basalt formed from sulfur were also common. Moreover, many black basaltic rocks (particularly those to the north of playa corolla, where the blue footed boobies nest) were covered in layers of white guano. The island has a number of gradient color choices. Perhaps it also contains room for different specialized varieties?
I considered this idea over several days, always watching the lizards and noting their colors and proclivities for specific gradients. This explanation requires a barrier to gene flow. Most speciation models advocate allopatry (speciation by geographical separation) as the preferred model of evolutionary divergence. Even the numerous finches occurring sympatrically on the same islands were presumed to have evolved separately, only to later colonize and assume their distinct niches. As outcrossing between subpopulations would exert a homogenizing pressure on the distinct color patterns, the idea requires sharply defined microhabitats. But the different gradient
Figure 2. A male (top) and female (bottom) M. buittatus on San Cristobal.
patches are anything but sharply defined. Black rocks spill out right onto the white sandy beaches of San Cristobal. Moreover, much of the color variation I sought to explain occurred between lava lizards occupying the same gradients. What gene flow barriers could possibly maintain such closely related, neighboring varieties?
However, active-camouflage could easily explain the observed differences. Perhaps the lava lizards simply change color in order to blend into their surrounding gradient. This phenomenon, familiar in the form of chameleons and octopi, is called physiological color change. I searched the literature on lava lizards and found documentation of color changes with reproductive maturity, pregnancy, and “mood”, but not active-camouflage or thermoregulation. Of these, mood-mediated color change is the only one that would qualify as physiological (assuming that the lizards change moods with some frequency). Physiological color changes happen on the short-term in response to local stimuli. Male marine iguanas take on red and blue coloration during mating season, but this change in pigmentation occurs through the long accumulation of chemicals found in their food. Octopi, on the other hand, rapidly change color to blend into the ocean floor—the effect is almost instantaneous. Thus, the color changes of male marine iguanas and lava lizards at different maturity levels or stages of sexual readiness are not characterized as physiological, while the color changes in the octopi are. As a sort of arbitrary cut-off point, I call all color changes that occur within thirty minutes “physiological”, and ignore gradual color changes that occur over larger timescales.
I confided in several people my suspicion that lava lizards change color physiologically but received little in the way of encouragement. Everyone from Diego, our naturalist guide at el Junto, and my host-mom Patti demurred (of these, only Patti would be won over by evidence). Undeterred, I proposed a project that involved capturing the lizards and performing experiments. While Dr. Mackie enthusiastically endorsed the idea of a controlled experiment, the staff at GAIS was somewhat less enthusiastic. Handling animals requires special permission from the Galapagos National Park. Collecting the lizards for experimentation was held-off until permission could be secured. Moreover, my ideas, in addition to being without precedent in the scientific literature, were far from inductive. Essentially, I just had a hunch the lizards changed color. Few people save for myself were excited by the prospect of venturing into the ambiguous grey areas of the law to chase the proverbial wild-goose.
Soon enough I was talking about the lava lizards like Lewis Carroll’s Cheshire cat, who could appear and disappear at will. Finally, one night Diego simply told me the lava lizards “are not like chameleons.” While I had done my research and knew no one had actually tested this proposition, I was nevertheless at a loss for a ready rejoinder. This comment forced me to realize, with a start, that I did not know what a chameleon was like. How does color change occur in species in which the phenomenon has been well documented? I meant to find out.

Chromataphores and Physiological Color Change

The dermis of reptiles, amphibians, fish and cephlapods (squid and octopus) contain pigment-containing cells called chromatophores. Chromatophores are organized depending on what type of pigment molecules they contain. The following bullet points characterize the major chromatophore families:
•Xanthrophores (yellow)—pteridines
•Erythrophores (red)—carotenoids
•Iridophores (iridescent)
•Leucophores (white)
•Melanophores (black/brown)
•Cyanophores (blue)—common in poisonous frogs

These dermal cell types tend to be organized into three dimensional dermal-chromatophore units (DCUs). Light reflected off the iridescent iriodphores is captured by overlaying xanthrophores and erythrophores, giving the animal its color. For instance, the green color of the iguanas at Tiputini was caused by xanthrophores filtering yellow out of light reflected off the iridiophores. Light reflected off the iridiophore is not always filtered by overlaying pigment. The metallic color of many teloest fish is caused by light reflecting unfiltered off dermal iriodphores.
Physiological color change occurs when pigment in the chromatophore layers aggregates around the cell nucleus or disperses into the cytoplasm. The aggregation/dispersal of the black pigment melanin in melanophores is the easiest to observe. When melanin is aggregated around the nucleus, light is allowed to reflect off the iridiophores and scatter according to the concentrations of the other chromatophores. When melanin disperses into the cytoplasm, the cell goes dark and no light can get through. The effect is rather like opening (aggregating) and closing (dispersing) blinds along a window pane. As M. buittatus appeared to vary only along a gradient from dark to light, my discussion will focus primarily on melanophores.

II. Hypothesis

While observing the lizards and performing the requisite literature searches, I came up with a number of hypotheses. I have listed these as they appear in my notebook along with some predictions made by each.

Active Camouflage

Rationale

The lava lizards change color in order to blend into their surrounding gradient. The lizards detect the gradient color through thermal cues. Black gradients soak up more sun than white gradients and consequentially reach higher temperatures. Thus, hot lizards turn black and cold lizards turn white.

Predictions

The color-change rate should follow the general pattern for positive feedback mechanisms. Thus, when a lizard turns black on a hot surface, it should soak up more sun and accelerate the rate of body temperature increase. Similarly, when a lizard turns white on a cool surface it should soak up less sun and increase the rate of body temperature decrease. This mechanism would increase the temperature range experienced by the lizard, requiring it to be poikliothermic (like marine iguanas, whose body temperature fluctuates widely during the day). Small lizards should change color faster than large lizards since surface area to volume ratios decrease with size. Also, it should be possible to coax lizards into assuming a color opposite the gradient by providing false-whites (or hot white surfaces) and false-blacks (cold black surfaces).

Thermoregulation via Temperature

Rationale

The lava lizards change color in order to maintain a constant body temperature. The lizard changes according to body temperature, but does so in order to mismatch the gradient.

Predictions

The color-change rate should follow the general pattern for negative feedback mechanisms. Thus, when a lizard starts heating up on a black surface, it should turn white and decelerate the rate of body temperature increase. Without a gradient choice, the lizard should turn the opposite color of gradients kept outside its homeostatic temperature range (this is the exact opposite of poikliothermy). Contrarily, the lava lizards should match false-whites and false-blacks.

Thermoregulation via Light

Rationale

The lava lizards change color according to the rhythms of day and night in order to maintain metabolic rates appropriate to the time of day. The lizards appeared darkest in the early morning and on overcast days and lightest in the late afternoons—both fluctuations correlated with changes in light intensity.

Predictions

Lizards kept in the dark should be darker than lizards exposed to the light on either gradient. Similarly, lizards kept hot but shielded from the light should show no differences in coloration with lizards kept in a cold-dark. See discussion for a more in depth explanation.




III. Methods and Additional Observations

After waiting for several days, word came back that the project would be permitted. The lemon-ant group—myself, Yukari, and Katie—was reunited in order to carry out an experiment. Unfortunately, we lacked lab apparatus of any kind. The lizards could not be stored in a terrarium. Instead, a half-dozen cardboard boxes were obtained gratis from a local snack-foods merchant named Maximo. We would have to make-do without integral adjuncts such as a thermometer to measure gradient temperatures and a spectrometer to quantify the intensity of light reflected off the lizard. The only lab supplies we possessed were string from Yukari’s host mom and a Tupperware complements Patti Iturole.
Our experimental design was simplicity itself. We walked out onto the trail between playa man and playa corolla collecting the hottest lava dirt I could find. Temperature was determined simply by feeling the ground with the palm of my hand, an activity I’d grown accustomed to during the long hiatus between project proposal and data collection. Later, we obtained white organic sand from the beach of playa man. These two gradients were loaded into a cardboard box with a central divider. One side was filled with organic sand, the other with black lava dirt. These two substances formed the experimental gradients.
Collection began at 2:40 pm while the lizards were still sunbathing. The males were found perched up atop tall boulders—prime real estate for attracting a female. Due to their insensible habit of directing territorial displays at me rather than fleeing directly, the males were considerably easier to catch. There exists a size gradient of lava lizards that matches their vertical gradient—the largest males occupy the tallest boulders, while the smaller juveniles scramble along the lower rocks. This undoubtedly reflects the pecking order amongst M. buittatus. As afternoon became evening I saw females with a greater frequency. These yellowish lizards ate flies voraciously and were very difficult to approach. My success percentage at the beginning of the collection was around 20% for males and females, peaking at about 75% for males and only 50% for females. I found that both males and females were equally likely to bite (about 1 of 6, or 16%) and that the effect of being handled calmed them down considerably. Thus, the lizards would permit me to inspect and pet them under their jaws, closing their eyes in a manner comparable to a domesticated iguana receiving a similar caress. Of course, given any opportunity to flee, they would leap from my hands and run away. When I had collected twelve lizards (six males and six females) I called it a day and stuffed Patti’s tuperware, now full of lizards, in my backpack. Naturally I provided air-holes and left the bag slightly unzipped.
Our first day of data collection was a mess. Each lizard had spent the night in a covered cardboard box with absolutely no sunlight. Lacking a means to standardize lizard coloration measures, we choose to simply photograph each lizard at zero-time (immediately after being removed from the box), 15, and 30 minute time intervals. At 2:30 pm, on June 10th we split up the lizards according to size and sex. The following figure describes our experimental set-up:

Lizard ID
Gradient
A [♂s]
Organic Sand
B [♂d]
Lava dirt
C [♀s-nongravid]
Organic Sand
D[♀d-gravid]
Lava Dirt
E [♂s]
Organic Sand
F [♀s-nongravid]
Lava Dirt

Several lizards were released due to time-constraints. During the delay between lizard collection and observation I provided the lizards with insects which happened to fall into the foot-wash basin outside of GAIS. While the lizards ate these proffered meals, they were singularly uninterested in dead prey. Handling the lizards on June 10th I noticed many had lost some girth, though none appeared emaciated. Interestingly, no lizards were cannibalized in captivity. While collecting lizards I observed a juvenile with a tail hanging out of its mouth. Several students observed a similar phenomenon and asked me, wryly, how such a small lizard could consume a conspecific of roughly equal size. After observing the lack of cannibalism in captivity, the ubiquity of auto-amputation scars, and the normal insectivorous feeding habits of these lizards, I consider it unlikely that the juveniles were truly cannibalistic. Perhaps these lizards merely feed opportunistically on severed tail segments, which move around like an unearthed worm after being dropped. If someone could capture cannibalism on film, that would be quite astounding (and a complete refutation of this hypothesis). Why should only juveniles be observed eating other juveniles, and no adults observed eating juveniles, when adults would presumably make for better cannibals?
At 2:30 pm, the sun was not directly overhead, and the tall sides of the cardboard boxes provided shade over half the gradient. This confounded our experimental set-up, as the temperature differences between shaded gradients is less than gradients allowed to heat up in the sun. Moreover, both lizards showed marked preference for the shady gradients after short exposure in the direct sunlight (but the lizards on the lava dirt more so). To reduce shading, the sides of the boxes were trimmed down. However, this posed the immediate problem of allowing the lizards a means to escape. Several times I would have to chase the lizards down and re-capture them. I built a “lip” around the top of the box with packing-tape, and this helped keep the lizards from escaping, but every time I moved in to take a picture they would all attempt to jump out simultaneously. One lizard dug a burrow in the lava dirt and emerged underneath the barrier in the organic sand on the other side. This was beyond frustrating. A word of wisdom: it’s not possible to anticipate all the difficulties of working with animals.
I came up with an idea to both reduce shading and keep the lizards where I wanted them on our second day of data collection (June 11th). This time, observation started at 12:00 pm, with the sun directly overhead, and continued until only 12:30 pm. The tape-lip was removed and adjustable lizard-leashes were constructed out of string. I fastened these leashed anterior the hind legs and tethered the other end to the side of the cardboard box. The lizards hated these leashes at first, opening their mouths and biting at my fingers when I attempted to handle them, but eventually they settled down. Digital pictures were taken with no flash in the shade at the four time intervals (0-time, 15 min., and 30 min.). See the results section for an exposition.

IV. Results
A0
A0
A15
A30
Figure 2. A male (top) and female (bottom) M. buittatus.
B15
B0
B30
C0
C15
C30
D0
D1515
D30
E0
E15
E30
F0
F15
F30
Note that the letter corresponds to the lizard ID and the number to the time interval (0-time, 15 minutes, and 30 minutes). The results demonstrate that the red dorsal crests of the male lizards turned white when placed into the sun. Similarly, the red scales adjacent the dorsal crest disappeared. The white scales over the male lizards appear brighter and more pronounced. The males kept on the white sand appear brighter than the males on the dark lava dirt. The females show little variation in color.

V. Discussion
Male M. buittatus exhibit physiological color change, while females do not. Moreover, when placed in the light, males on either gradient changed in the same direction (towards a white dorsal crest, brighter white scales, and no red scales). However, the color change in the males kept on the cooler white surface was more pronounced than the males kept on the hot lava dirt. With these facts it is possible to evaluate some of the hypothesis mentioned in section II.
First, the active camouflage hypothesis is refuted. Males on either gradient became lighter. This hypothesis expected the lizards to become light on the white sand and dark on the hot dirt. Thus, the appearance of gradient matching in males is not caused by any causal effect of the gradient.
The thermoregulation via temperature is strongly contradicated. This hypothesis expected lava lizards to be darkest after being kept in the cold (which they were) and then turn white when heated up (which they did). However, the lizards on the black gradients heated up faster but experienced a less pronounced color change. If the lizards assume a lighter color in order to cool off when heated above a homeostatic temperature, they should change most at higher temperatures.
This leaves thermoregulation via light, which is generally supported by the results. This hypothesis makes the same expectations as thermoregulation via temperature but can also tentatively explain the greater color change on the white sand. Here it is necessary to make a short digression.
The melanin dispersal/aggregation mechanism mentioned in section 1 dealt with the changes within chromatophores that accounted for physiological color change. However this discussion left the issue of what triggers the dispersal of melanin unanswered. Melatonin is one neurohormone commonly associated with melanin dispersal. This hormone is familiar to many humans as a non-narcotic sleep aid. In mammals melatonin is a hormone used to measure the circadian rhythms of day and night. The pineal gland, a pea-sized projection of the epithalamus once described by Descartes as the “seat of the soul”, secretes melatonin into the bloodstream at night. The familiar phenomenon of jet-leg is caused by feedback delays between the cycles of melatonin dispersal and the cycles of light and darkness.
Reptiles also possess a pineal gland with a connecting third-eye. This third eye (also called a “parietal eye”) communicates through the skull with the pineal gland. The third eye senses light but not motion or objects like the other two eyes. Might the third eye trigger melatonin secretion in the absence of light? Might heightened levels of melatonin cause melanin dispersal, giving the male lava lizard its dark color? This explanation is both testable and suggested by our data.
First, the lava lizards were darkest when kept out of the light. Similarly, prior to data collection I noticed lizards were darker in the early morning and on overcast days. Oftentimes, the intensity of sunlight and gradient heat are proportional, making it difficult to separate the effects of heat and light. However, lava lizards on the white organic sand assumed a lighter color than the lizards on the hotter lava dirt. Could this be due to the fact that a gradient that reflects light exposes the third eye to higher light intensity? It is somewhat difficult to imagine this being an issue with the third eye mounted atop the lizards head, but the lizards in our study group were often engaged in tilting their heads sideways to see over the walls of their enclosure. Also, on the first day of data collection the organic sand portion was mostly shaded while the lava dirt section was exposed to more direct sunlight (see Figure #). This photograph, taken at fifteen minutes (and only shortly before the experiment had to be rescheduled due to escaping lizards) after the lizards were placed into the sun, shows an opposite result as the one yielded when both portions received equal amounts of sunlight.
A direct test of this hypothesis would involve building parietal blindfolds to prevent the third eye from detecting light. I predict the lizards that are blind-folded will show no color change at all (retaining a red dorsal crest). This is a test I would loved to have done, but the lizards were losing weight, the entire experiment was illegal, and we simply lacked time and resources.

June 14
Goodbye San Cristobal

Today was our last day on San Cristobal. We presented the results of our sea lion project and watched a puppet show put on by my host-dad David (who had just returned from Quito). I also had some free time to check out some blue-footed boobies near playa corolla.
Blue footed boobies have blue feet. This shouldn’t be surprising, but the explanation as to why they have blue feet seems particularly lacking. In short, blue footed boobies are supposed to have blue feet because of the high circulation of blood through foot-tissues. This blood is used to keep booby chicks warm.
This may be completely true, but it strikes a nerve with me. I’m an emergency medical technician, and I know from experience that when a patient turns blue, he or she is not experiencing excellent circulation. Blue is the color of oxygen-deficient blood. Blue is the color of suffocation. If blue footed boobies have blue feet to keep their chicks warm, what about red footed boobies? These questions plagued me during the trip and I still have no good answer for them. One naturalist guide suggested that the blue feet played a role in attracting mates. That seems promising, but females also have blue feet. Without sexual dimorphism it’s difficult to posit an explanation of a trait via the theory of sexual selection.
Blue feet define the booby, but one of its fishing behavior is the most awesome thing about them. Blue footed boobies dive into the water at a ninety degree angle. They aim for under the fish and then grab hold of it on the way back to the surface. This is a rather direct solution to the problem of diffraction. Light travels at different speeds in different media. This phenomenon causes light to bend where media meet (for instance, water and air). From above the surface of the water fish appear to be shallower and larger than they actually are. Coming at fish from directly above and/or diving down and confronting them under the water allow the boobies to secure their catch.
Today many of the students were coming to terms with leaving their host families. David agreed to put on a puppet show for the entire class so I invited everyone to my homes-stay for a little pre-presentation entertainment. David did not disappoint.
I suggested he perform his Darwin puppet show. He obliged. This, in short, is the plot of this show (a David Itturaole original):
A swallowtail gull is born mysteriously with a red rim around his eyes. None of the other gulls possess this trait and he becomes an outcast. One day as he flies around the islands, he’s swallowed by two frigate birds. One frigate bird puppet is made out of an umbrella (which he opened and closed to simulate flying). The other frigate bird is supposed to be played by a human actor. This bird was to be a traditional comic foil—the dim witted henchman to the puppet’s clever honcho. The gull spends many nights inside the stomach of the frigate bird where he learns to use his red rim to see in the dark. After hatching a daring escape, the gull goes to the Great Owl for advice.
The Owl tells him to convince the other gulls to learn to fish in the dark, when the frigate birds will be unable to harass them. The gull tells the others and the rest is history—the swallowtail gull becomes nocturnal. Darwin makes a late entrance. Already possessing his recognizable white beard, he shows up on the island and goofs off for a while. He grows bored, says that he’s hungry, and walks right past the swallowtail gull without making a single observation.
Eddie asked my host mom if the show as supposed to be anti-evolution, an allegation she denied. She had an interesting view on the scientific theme of the puppet show. Patti saw selection as a way to produce harmony in nature by specializing each living thing to its own niche. Thus, the blue footed boobies fish inshore, while the red footed boobies fish out at sea. The frigate birds are diurnal, while the swallowtail gulls are nocturnal. In short, she felt that the message of nature was one of conflict-avoidance. I was surprised by the passion with which she explained her views, as we had yet to discuss any “deep” topics (due to my meager vocabulary). Her ideas were interesting, but they are not my own. The parsing out of organisms into different niches belies the competitive struggle that brought it about. Evolution occurs via the process of non-random death—the grim reaper. Many species are driven extinct through the same physical processes that mold others into organisms specialized for a different niche. In short, Patti’s view of nature simply wasn’t macabre enough for me.
I’ve discussed the results of the sea lion study elsewhere and will pass over it here. Our final night on the islands afforded me a view of the most beautiful sunset I’ve ever seen. As I stood on the beaches of playa mann I though “will I ever set foot on this island again?” I decided it was just as likely as anything. I thought: who knows what the future will bring? It’s better to not think about it and just watch the sunset.

June 15
The Highlands of Santa Cruz


Today we left San Cristobal and took a boat to Santa Cruz. After lunch at Puerto Ayora we met our naturalist guide Fabricio. Fabricio had been up all night drinking and was worse for the wear.
We took a bus to the highlands to check out some dome shaped tortoises. The vegetation around the tortoise reserve of caseta and el chato are rich in scelasia trees and pega pega grasses. These tortoises are considerably larger than the saddle-backed variety we saw on San Cristobal. Again we observed the tortoises wallowing in small freshwater ponds. We also had a chance to inspect some empty carapaces. These shells were large enough for several students to crawl inside (they entered through the front and stuck their legs through the two holes in the back. When I flipped these shells over it was easy to see which sex they belonged to. The male shells have a concave underside, while the females are convex. I observed the same thing in sea turtles. However, the male green turtles I swam with off playa corolla on San Cristobal were smaller than the females. As these turtles copulate in the water, the males’ smaller size insures they do not drown the females.
I’m going to engage in some off-the-wall speculation here. I ask for your patience.
As I was looking at the dome-shaped tortoises I found myself thinking about the differences between the Galapagos tortoises and their closest relative on the mainland Geochelone chiliensis. G. chiliensis is a small-bodied tortoise (about 20 cm from head to tail) while the Galapagos varieties of G. nigra can grow larger than 1 meter. Certain qualities change size as a function of the square of linear dimensions while others change as a function of the cube of linear dimensions. For instance, brain-size is scaled towards the surface of an animal (square of linear dimensions) even though body weight is scaled towards the volume (cube of linear dimensions). As a result brain weight increases at a lesser rate than body weight when the dimensions of an animal increase. Thus, small bodied animals have relatively larger brains than larger bodied animals.
Some qualities that scale to a square of linear dimensions (such as brain weight or egg size) change size at a lesser rate within lineages than between lineages (see Stephan Jay Gould’s Bully for a Brontosaurus for an interesting essay on this phenomenon in New Zealand kiwis). For instance, brain size in human beings decreases at a lesser rate than brain sizes between human beings and other apes as body size decreases. Thus, if a large animal evolved towards a smaller size it might end up with an abnormally large brain (or large eggs or some other trait that scales to a square of linear dimensions).
If the size of the tortoises that originally colonized the islands is similar to that of the small G. chiliensis then those qualities in tortoises that scale to linear dimensions should fall well below the expected size (“expected” based on the sizes found in other reptiles). For instance, the eggs might be particularly small or the brains particularly puny. Is this true? I have no idea. I’ll chalk it up as another in a series of untested hypotheses.
The sex of tortoises is determined by the temperature of the eggs. It’s hard to imagine an entirely environmentally system of sex determination. There may be some adaptive value to biasing the sex ratio in a clutch of eggs under certain conditions. For instance, in times of low food availability a clutch of females may be a safer bet than a clutch of half males and half females. Females don’t compete for mates—most females that are able to survive to sexual maturity experience equal reproductive output (they can only produce one clutch per mating season). However it would seem presumptions to suggest that the conditions under which certain sexes are favored can be defined with a single measure.
Such were my thoughts at the tortoise reserve. Later we returned to Puerto Ayora and boarded the Guantanamera, a mid-sized cruise boat with a kitchen, open-bar, and small cabins for all the students. That night we would make a passage to Rabida island.

June 15
Rabida and Bartomelo Islands

Today we woke up to the sound of the dinner bell. The night previous, our boat made a gentle passage from Santa Cruz to Rabida, where we’d make our first dry landing. Rabida is a small island (only 5 square kilometers) with no human inhabitants. Unfortunately, we were unable to see any flamingos in a salt-water lagoon about twenty meters inland. Flamingos eat brine shrimp, which require a high salinity environment (20% salt, compared to 13% in the sea). When water evaporates off the surface of a lagoon the salinity increases, making for an ideal reservoir for the salt-living brine shrimp. Unfortunately for the flamingos (and the brine shrimp, for that matter), Rabida’s resident sea lions had been using the lagoon as a toilet. Its stagnant waters were an uninviting yellow-brown. As no brine shrimp could survive in this lagoon, no flamingos could survive on the island.
The optunia on Rabida sprout succulent leaves close to the ground, presumably on account of the lack of herbivores. No land iguanas or giant tortoises roam on Rabida. . We had a chance to see some blue-footed boobies. These birds have the insensible habit of laying two eggs, though only one chic can survive. This is common amongst inshore birds. For instance, pelicans (whose nests we also observed at Rabida) lay two eggs and fish close to shore. The explanation for this phenomenon seems to contradict itself—presumably the birds that feed in shore can afford to feed two chicks. However, if only one bird survives, the effort of developing and incubating two eggs then feeding two chicks during the first few weeks of development is a complete waste. In the case of blue footed boobies, one chic ejects the other forcibly from the nest. The nests of the blue footed boobies are formed from white excreta (the bird points its butt in each direction and craps in each direction, forming a crater of guano). When the ejected bird is pushed outside the circle of excreta the mother denies it re-entry into the nest.
Adult males reputedly know a special dance to gain entry into the nest. The ejected chicks cannot perform this dance correctly and die shortly after being ousted. Nature can be macabre in its solutions to life’s problems. It’s been suggested that the costs of rearing two offspring to an early stage of development is low enough for inshore feeders that it doesn’t overshadow the benefits of producing two ‘prototypes’. To insure that the better of the two is the only one fed the parents make no distinction between a foreign invader (for instance a black rat) and an ejected chic. Each blue-footed booby and pelican we observed had already come out on top in this infant-gladiator game. Thus one can imagine that there selection strongly favors chicks that come out of the egg ready to fight. Necessity is the mother of invention.
After lunch we left Rabida and proceed to Bartomelo Island. I spent the midday passage at the bow of the ship and I can attest it was one of the strangest sites I’ve ever seen. We set up a respectable stereo system and listened to music as the shoreline of Santiago passed by our leeward side. I can see why pirates called these islands “enchanted”. The black-boulders take on an other-worldly character when viewed from the sea.
At Bartomelo I had a chance to go scuba diving. I admitted to Fabricio that I didn’t have a license. This was not a problem. He’d show me how to retrieve my regulator and adjust my depth and a few other tricks (like clearing my facemask of water). We wouldn’t be going down further than 15 meters anyways—a very safe introduction for a novice. Of all the students, only Yukari, Stephanie D., and myself opted to go diving (probably due to the largish $75 cost involved). This experience was thrilling.
While there is not much you can see diving at 15 meters that you couldn’t observe snorkeling from the surface, the ability to stay submerged and inspect marine life up close more than justifies the added equipment. While diving I saw several variety of ray (including one small enough to fit in the palm of my hand), several tiger ells, reef sharks and a red-lipped batfish. The red-lipped batfish was a singular oddity, even on a journey filled with nature’s most extraordinary beings. This fish appears almost like an underwater frog. The pelvic fins are analogous to the hind limbs and the pectoral limbs to the forelimbs. While we observed this fish, it simply walked around on the bottom of the ocean paying us little mind. This creature looked like a throwback to the Devonian epoch, when fish first crawled out onto the sea and became amphibians.
Later we walked up to a lookout point and saw one of the archipelago’s most iconic images—pinnacle rock. As we reached the summit of this lookout we had a chance to see some spatter cones where lava flows were diverted as pressure built up in the magma tube of the main crater. The scene of pinnacle rock was created when an enormous section of rock simply fell into the sea. This is an image to inspire awe.

June 16
Genovesa Island

Today we visited Genovesa Island, one of the jewels of the archipelago. The night previous we had our roughest passage yet. I was tossed around the small cabin as it rocked back and forth without reprieve.
Fabricio wanted to wait until later in the day to make a wet landing on the beaches along Darwin Bay. This bay is a volcanic caldera collapsed along the south end. We started out the day with some snorkeling and a dry landing. Walking along the beach we saw swarms of petrals. We were on the look out for barn owls, which pounce on these petrals and tear their wings off. The left overs form owl feasts could be observed—a pile of discarded wings covered in white guano. This would have been interesting to see, as the owls are scarcely larger than their prey. We tried to peak inside several caves but none could be seen. The mockingbirds on Genovesa are attracted to water bottles. I set mine down for a moment and one hopped right up along side of me.
Later we had lunch. As the scraps from lunch were thrown overboard a mass of fish came to feed. With the fish came sharks. The leeward side of the Guantanamera quickly became a bloody feast. This inflated our egos considerably—we were only hours before diving off the top of the boat with garish abandon.
Our wet landing on Genovesa was the highlight of our tour of the Galapagos Islands. The island is covered with red footed, blue footed, and masked boobies, as well as great and magnificent frigates. These birds were more densely packed than anywhere we’d previously visited. Finally we saw male frigate birds with inflated red pouches. Many students marveled that the pouch didn’t catch on the nesting materials and deflate like a balloon. Fabricio said simply that this didn’t happen. He’d spent ten days sitting on the islands with David Attenborough just watching these frigates a few years ago. Attenborough was filming a documentary on the archipelago and needed a shot of a frigate bird stealing nesting materials. It’s hard to imagine this took ten days. We saw this happen repeatedly within the course of a few hours.
Frigate birds are called kleptoparasites—they steal food and nesting materials from other birds (particularly red-footed boobies). Many times we observed frigate birds dive bomb the boobies, who fled rather than fight.
Red footed (top) and Nazca (bottom) boobies
Female (top) and male (top) great frigate birds While on Genovesa I had a chance to observe a phenomenon alluded to in my discussion of the sea lions of San Cristobal. A large juvenile was suckling at an adult female of roughly equal size. As I approached, the juvenile looked up at me and whined with a very pup-like drawl. Comparatively, non-suckling (or “free-living”) juveniles made more adult-like sounds. Adult females use the characteristic feeding cry of their cubs to pick them out of the pack after a fishing bout. It’s possible that the late weaning of large juveniles may be caused by the retention of pup-like calls. This would be interesting to study. One animal hardly constitutes solid evidence, but I’d wager that free-living juveniles have more adult-like calls while suckling juveniles sound more like pups.
It was singularly unfortunate that we were unable to see flamingos on Baltra as they would have provided the perfect contrast with the penguins we saw on Genovesa. The Galapagos penguin is the smallest in the world and the furthest north. They thrive on the islands due to the cold waters of the Humboldt Current. It’s not particularly surprising to find the smallest penguin occurring in the warmest regions. Warm blooded animals generate heat along their volumes (measured as the cube of linear dimensions) and lose it across their surfaces (measured as the square of linear dimensions). Thus, smaller animals radiate proportionately more heat off of their surface than larger animals and have a difficult time thermoregulating. This problem is diminished by the warm climate of the islands.
Red footed boobies nest up in trees and lay only one egg. They are pelagic birds and are not endemic to the islands. However, these birds are also possess a color polymorphism—some are white and others are brown. The relative proportions of white to brown on the islands and the mainland are completely reciprocal. Stated less ridiculously, 95% of the boobies on the islands are white and 5% brown, while 95% of the mainland boobies are brown and 5% white. These birds do not mate preferentially with one another—“interracial” couples are common. The relative differences likely reflect random genetic drift and not selection. Perhaps the original red footed colonizers of the islands just happened to be predominately white (through mere chance). On the islands this rare color type would not be weighed down by the genetic inertia off the brown types on the mainland. This is pure speculation (a common dominator in many of these hypothesis).
We saw mating on the islands as well. Two frigate birds began copulating while we were all facing in the other direction. When someone pointed it out, I grabbed for my camera but was unable to fish it out of its case before the event was over. We observed many swallowtail gulls. These birds were invariably seen in groups of two. Fabricio pointed to two gulls attempting to mate. “It’s too windy,” he said. “The male’s gonna fall off.” Shortly afterwards, the male did fall off. I must admit here that I am frankly unable to see how swallowtail gulls mate. The male perches up on the females back, but never appears to go in for the vaginal kiss. In every picture I’ve seen of swallowtail gulls “mating” they are similarly postured—the male standing atop the female.
After dinner we prepared for our trip to North Seymore island (separated by a narrow channel from Baltra). The passage to Genovesa was rough and Fabricio assured us that the way back would be even worse. Thus, I decided to spend the night on a lawn chair on the bow of the ship. The cool breeze helps immeasurably. As we made our journey south I looked up at the night sky. Never has the sky seemed more beautiful—not even in Tiputini, when I marveled that I wasn’t sure which hemisphere I belonged to. Shooting stars flew across the sky at a rate of about two every hour. Nocturnal swallowtail gulls followed our boat. That night, as we crossed the equator, I felt like a citizen of the entire Universe.
North Seymore to Santa Cruz


Today was our last day on Guantanamera. We started the day with an early dry land on North Seymore and then went from Baltra to Santa Cruz.
During World War II Ecuador allowed the Unites States to set up a naval base on Baltra. The US soldiers, I’m sorry to say, used the land iguanas on Baltra for target practice. Soon there were no land iguanas left. Recently the Darwin Station has attempted to introduce some land iguanas on North Seymore (as sort of a natural breeding ground that could generate iguanas for Baltra). The project failed miserably—the soils of North Seymore are rich in oxidized irons that heat up in the sun. None of the eggs could incubate properly and the introduced iguanas died. Darwin Station then breed and reintroduced iguanas to Baltra directly. This effort was successful.
The optunia on North Symore have succulent leaves close to the ground. This is a feature of all of the cacti in herbivore-free areas. On the islands, herbivore is synonymous with large reptile. According to the oft-repeated wisdom, optunia grow tall in areas with herbivores and short in areas without them. However, as I walked the streets of Puerto Ayora I came across many potted optunia. They were all tall (despite the lack of herbivores). Now this could be interpreted merely as a statement of the lack of phenotypic plasticity in optunia cacti. However, perhaps optunia respond directly to the soils. This would make for an interesting experiment. The guides gave me every reason to believe that the correlation of herbivore presence and tall cacti was used to infer causation (rather than a direct test). Would a tall-growing optunia still grow tall in high-iron soils?
Later at Santa Cruz we visited Tortuga Bay. Here several students invented a brilliant and complicated game. They called it Frig Ball. In short, Frig Ball consists of grabbing hold of thick tufts of kelp and throwing them at someone of an opposite gender. The game got its name as it involves stealing other players kelp balls (just as frigate birds steal boobies nesting material). Interesting stuff.

More than 170 years since he first set foot on the islands, Charles Darwin continues to cast a shadow over the Galapagos archipelago. Tourist traps and interpretation centers are pregnant with Darwin paraphernalia. His bust is printed on t-shirts and coffee mugs, almost always in its venerable, white-bearded variety. The burgeoning young naturalist of the HMS beagle—the Darwin who visited the islands—is not as readily recognizable (and hence not as easily marketable). The elder Darwin is an icon established and sage (albeit moribund); as far convinced and advanced in his evolutionary musings as he’ll ever get. He’s the Darwin staring back at me, nodding approvingly with an adorable bobble-head.
But the name exploitation is not limited to the niche of t-shirt retail. Every island has its Darwin Avenue (and probably its Evolution Boulevard, and Finch Street as well). The naval base on San Cristobal features a prominent statue of the elder Darwin, a man who wasn’t shy about his near-pathological sensitivity to sea sickness [wrote Darwin, in the preface of A Naturalist’s Voyage (1845), as advice to young naturalists interested in seeing the world: “If a person suffer much from sea-sickness, let him weigh it heavily in the balance. I speak from experience: it is no trifling evil, cured in a week.” Privately, he referred to his collected sea passages as “one continual puke”]. Perhaps most tellingly, the technical advisory center for the Galapagos National Park and the Marine Reserve is called “Darwin Station”. Yet Darwin no more founded the research center than he did the “Charles Darwin Travel Agency” (found at 132 Darwin Ave., Santa Cruz).
Even the finches bear Darwin’s moniker, though for priority’s sake they might be called Gould’s finches (after the English ornithologist John Gould), and for peat’s sake they ought to be called the Grants’ finches (after Peter and Rosemary Grant of Princeton University). But folk-history tends to record scientific discoveries as being precipitated by a startling impetus, followed by almost immediate understanding: Archimedes sitting in a bathtub exclaims “eureka!”, realizing the volume of an object can be measured by submerging it in water, Newton conceiving the idea of gravitational attraction after being struck in the head by a falling apple, and Darwin unraveling the mysteries of evolution in a paltry twenty-two day stay on the Galapagos Islands. Rarely in these popular accounts can one find mention of collaborative efforts or the circuitous process of gathering evidence or trial-and-error, of science “warts and all.” Science, like any discipline, needs its heroes. However, after visiting the islands and being subjected, repeatedly, to the canonical tale of Darwin’s discovery, amidst a plethora of Darwin merchandise, I’m convinced it sorely needs some perspective as well.
According to the popular account, Darwin was a seminary student convinced of the immutability of species before he got to the islands. Afterwards, having come face-to-face with evolution, he set the course for all his later work. The purpose of this scientific block is to investigate the evolution of Darwin’s thinking and the actual role the Galapagos flora and fauna played in the formulation of his ideas on descent with modification. Here I seek to unravel the popular account and see if it has any utility as a historical explanation. In so doing, much light will be thrown on Darwin, the islands, and the process of scientific discovery.
The first parts of the canonical story are essentially accurate. Darwin was a medical school drop-out and, before departing for his voyage around the world, he received a Bachelor of Arts degree from Cambridge (the normal preliminary degree for a seminary student). However, it is not true that work in the Church of England precluded the study of science. Two of Darwin’s mentors at Cambridge, the geologist Adam Sedgwick and the botanist John Stevens Henslow (who recommended him for the Beagle expedition) were ordained in the Church and pursued active scientific careers. Theology and science were intimately bound in the early-to-mid nineteenth century. Entering the church was neither inimical nor anachronistic to the career of a young naturalist in Darwin’s age.
Another aspect of the official story holds that Darwin came from a strongly religious background, and that this either delayed his acceptance of the mutability of species or presented a barrier to his understanding, requiring a revolutionary secularization in the field (perhaps amongst the basaltic rocks on the shores of the Galapagos themselves). But there is no record that the Darwin’s were religious enthusiasts. A young Darwin was tutored in religious matters by the Reverend George Case, a Unitarian minister. Darwin’s father used to chide (albeit approvingly) that Unitarianism was merely a featherbed to catch a falling Christian (Browne 1995 p. 12).
It’s also important to consider the effect previous works on evolutionary theory had on a young Darwin. The French anatomist Jean Baptiste Lamarck had already published his Philosophie Zoologique (1809), in which he delineated an evolutionary mechanism involving the inheritance of creatively adaptive variation (as opposed to the dichotomy of random variation and nonrandom selection Darwin later favored). More importantly, Erasmus Darwin, Charles’ paternal grandfather, described the concept of progressive natural flux abetted by sexual congress as a source of new species in the verses of his poetical Zoonomia, or the laws of organic life (2 volumes, 1794-1796). While neither of these books provided the synthesis of facts or the rigorous theoretical model provided by the younger Darwin in The Origin of Species, both would have been familiar works. As an intellectual (though lazy) student inclined towards natural history, Darwin would have been comfortable enough with evolution to consider it an interesting hypothesis, worthy of additional attention.
By the time Darwin made it to the Galapagos Islands (near the end of 1835) he had been geologizing all around South America. While Captain Robert Fitzroy piloted the Beagle around the east coast of South America making detailed plots of the coastline for the Hydrographer’s Office of the Admiralty, Darwin had spent most of his time on land. Here he speculated on the gradual ascension of the Andes, discovered a fossilized skull of the giant Megatherium, made surreptitious deductions on the formation of corral atolls (finding support only after visiting Australia towards the end of his journey), misidentified a geographical variety of the ordinary South American rhea (later learning from his mistake, a common denominator in many of his most important revelations), and rejected the polygenist version of human history in favor of a model of common origin for all races. The Galapagos were not in the original Beagle itinerary. Darwin, perhaps goaded on by the writings of Captain George Byron and the buccaneer-naturalist William Dampier (both of whom described visiting the islands), convinced Fitzroy to make a digression.
It is here that the chief myth of t-shirt purveyors and brief biographical sketches reaches its crescendo of inaccuracy. None of Darwin’s evolutionary musings appear in his notes contemporaneously with his stay on the islands. His first hints at transmutation (in Darwin’s day, the word “evolution” was associated with an absurd homincular theory of development, in which a tiny fully formed human being merely increases in size during embryonic growth) occur in a small private notebook two years later, in 1837. What is today known as The Voyage of the Beagle was originally released in 1839 under the lengthy title Journal of Researches into the Natural History and Geology of the Countries Visited During the Voyage of the H.M.S. Beagle Round the World (for brevity’s sake, hereafter referred to simple as Voyages). In Voyages, Darwin describes the islands in only one chapter, 27 pages in length. Voyages’ most important contributions to Darwin’s later publications on descent with modification are the result of collaboration, one he acknowledges in the preface. The classification of the bird specimens of the Galapagos (including the finches, provided in large part by Captain Fitzroy and Darwin’s manservant Syms Covington) by the ornithologist John Gould and the reptiles by herepetologist Thomas Bell provided him the hard facts he needed to form his analogy between spatial and temporal separation as a means of facilitating biological change.
Nor was the Galapagos experience so intellectually jarring that Darwin couldn’t delay publishing on evolution and spend the next twenty years pursing more conventional natural history pursuits: a monograph on the formation of corral atolls, five volumes on the zoology of the Beagle expedition, three more on geology, and eight years investigating the minutiae of barnacles. These studies provided Darwin with a wealth of facts and experience in natural history, a prominent position the elite scientific circles of Great Britain (which would later aid him in recruiting the help of naturalists around the world through the burgeoning English postal service), and credibility as a scientific author (with audiences and publishers alike). However, this long period also reflects lingering doubts, delayed priority and scientific celebrity, and periods of reflection and frustration as he slowly accumulated materials for his “big book on species”, a never realized multivolume work represented as a condensed abstract in the Origin. While preparing these materials, Darwin also made the essential connection between the writings of Thomas Malthus [Principles of Population (1798)] and the natural world. The three main aspects of his theory of natural selection—variation, heritability, and struggle—came together during this interval between the Origin’s publication and his return from the Beagle voyage.
The effect of the Galapagos Islands appears to have been largely retrospective, as if hidden from view until the essential theoretical framework and the central analogies of Darwin’s argument were worked out. However, the islands formed an indispensable support for his later argument. It’s interesting to approach the Galapagos with the methods toolkit available to a nineteenth century naturalist, noting which key observations Darwin used (both in the Origin and foreshadowed in Voyages) and which escaped him. The main arguments from the natural world available to Darwin were as follows:
1. Biodistribution. The theory of special creation held that each organism was perfectly adapted to its surroundings. One prediction of this hypothesis holds that anywhere an exploitable niche for an organism exists, so will the organism. If Darwin could show that the distribution of species was limited by physical constraints (for example, a continental plant that doesn’t occur on an oceanic island with similar conditions because its seeds can’t germinate after immersion in salt water), this technical claim could be refuted.
2. Variation. The pre-Darwinian concept of a species was static. Anatomist looked at members of a species as clustering around an abstract ideal (similar to Plato’s concept of art as an imperfect representation of an essential ideal). If Darwin could show that members of the same species varied according to local conditions, or, even better, if he could show variations insensibly intermediate between naturalists’ notions of “variety” and “species”, he could undermine the fixity of species.
3. Derivation. This is essentially a combination of the first two points. If a colonizing species had varied upon arrival to an oceanic island, it ought to appear derivative of some continental form. Going along with Darwin’s central analogy of geographic and temporal separation, this could demonstrate how speciation occurs.
4. Vestiges. Organisms with vestigial parts (i.e. parts that once had a function, but now remain as reduced or unused appendages) advertise their historical origin. Darwin compared vestigial parts to the silent letters retained by words rooted in other languages. Vestigial parts reveal an historical design process.
These five points are somewhat arbitrary and can be mixed together, but they set out a reasonable framework for evaluating the islands and Darwin’s publications. The third point, “Derivation”, includes homologous structures (structurally similar but functionally dissimilar, like the arm bones of a bat and a monkey).
In Voyages, Darwin correctly identified the islands as oceanic and recent in origin (“correctly”, inasmuch as modern methods of radiometric dating and paleomagnetism definitively vindicate him). From a transmutationary perspective, this is extremely important. Any colonizing species would not have had enough time to change drastically from its continental stock. The continental stock, in turn, would have neither the time nor the pressure of adapting to new conditions for great change. Thus, the continental forms appear ancestral to the colonists (though technically they must be as distantly related—genealogically—to the ancestors of the actual colonists as the colonists themselves). The great analogy, between time and space, is upheld. To quote Darwin (referring explicitly to the Galapagos): “Hence, both in space and time, we seem to be brought somewhat near to that great fact—that mystery of mysteries—the first appearance of new beings on this earth (Darwin 1839 p. 337).”
Darwin also noticed several tantalizing facts about the endemism and biodistribution. Only five of nineteen species (25%) of sea birds in the Galapagos are endemic (the Galapagos penguin, the flightless cormorant, the lava gull, the swallowtail gull and the Galapagos waved albatross, to be exact) (Constant 2006 p. 102). Comparatively, 22 of 29 species (76%) of land bird and all reptiles (with the exception of a few recently discovered introduced geckos) are endemic (p. 137). Then, as now, the island contained only one native terrestrial mammal (the rice rat), no amphibians, and thriving introduced pigs and goats. Darwin considered all of these facts amenable to a materialistic explanation.
First, he explained the greater number of endemic land birds in terms of the “greater range which these latter orders have in all parts of the world (Darwin 1839 p. 339).” In other words, endemism is more common in species “shipwrecked” on islands—like Daniel Dafoe’s famous Robinson Caruso—than in those species with greater means of dispersal. Darwin’s own mechanism of heredity theorized that offspring should appear intermediate between two parents (so-called “blending inheritance”). While this mechanism later turned out to be incorrect, it did emphasize the need for barriers preventing the interbreeding of colonists and their parent population. Interbreeding with the larger parent population would exert a homogenizing influence on the new population, preventing speciation. Today biologists still favor this model—dubbed allopatric speciation—as a source of new species (essentially for the same reasons).
Darwin likewise supported the idea that the absence of amphibians and large terrestrial mammals was a general law of oceanic islands. On the presence of endemic reptiles, but no amphibians, Darwin (1839) wrote: “may this difference not be caused, by the greater facility with which the eggs of lizards, protected by calcareous shells, might be transported through salt-water, than could the slimy spawn of frogs?” Moreover, Darwin considered the absence of frogs and toads a singularly surprising result “considering how well suited for them the temperate and damp upper woods appeared to be (p. 341).” It was not difficult for him to explain why large terrestrial mammals were not found on the islands—they couldn’t survive the 600 mile trek over the sea. More difficult to explain, under the theory of special creation, was the success of introduced goats and pigs (indeed, they are so successful the national park is constantly employed in their eradication).
The geologist Sir Charles Lyell, a young Darwin’s idol and elder Darwin’s friend and colleague, had set down much of the epistemological framework for Darwin’s “geologizing” around South America. Lyell’s uniformationism—the theory that the same physical processes occurring today occurred in ancient times—became a central feature in Darwin’s theories on corral atolls and the formation of the Andes (as well as his later theory of natural selection). But Lyell’s Principles of Geology (three volumes, 1830-1833) predicted that species should be inextricably tied to their geological conditions. The data from the islands, once reconstructed, plainly demonstrated the error of this view (and allowed Darwin to bud from simple acolyte to scientific revolutionary).
In fact, Lyell’s influence was so great that Darwin failed to properly separate his specimens according to which island they came from. It was just obvious to him that their local distributions should be roughly homogenous, given the similarity of the geological and climate conditions [Darwin (1839 p 352): “I never dreamed that islands, about 50 or 60 miles apart, and most of them in sight of each other, formed of precisely the same rocks, placed under a quite similar climate, rising to nearly equal height, would have been differently tenanted”]. As a result, Darwin had “partially mingled together” his samples from the different islands, and missed a key insight. Only after consulting John Gould (birds), Thomas Bell (reptiles), and Joseph Hooker (plants) could he recreate his most important argument for transmutation (via biodistribution) on the islands. Simply stated, different species of the same group occur on different islands. In Voyages Darwin calls this the “most remarkable feature in the natural history of this archipelago”. This simple fact—that each individual island is an endemism hotspot--introduces two important concepts: adaptive radiation and competitive exclusion.
For instance, Joseph Hooker (using Darwin’s samples) identified six species of scalesia tree on the islands (one each on San Cristobal, Isabela, Floreana, two on Santiago and a third of unknown origin), none of which occur on two different islands. Scalesia is an endemic genus of the Compositae (also known as the Asteraceae) or “sunflower” family. It’s now known that there are at least fifteen species of scalesia on the islands, with two species (Scalesia atratyloides and S. stewartii) very similar to each other. Scalesia come in twelve species of shrub and three species of tree. Yet trees are rare amongst the Compositae family, as well as amongst the Galapagos Archipelago. This illustrates an important aspect of adapting to an island with a paucity of established colonists: organisms converge upon forms and assume niches usually reserved for other species on the mainland. Hooker also classified seven endemic species of the widely distributed euphorbia genus, and noted that no island has more than one species.
Galapagos fauna show similar patterns of island endemism. In Voyages, Darwin regrets that he was unable to use finches in his key argument due to his poor notes on the origin of his specimens. Similarly, he relies on the notes of others (including Captain Porter of the U.S.S. Essex) and the claim of the Vice-Governor of the islands, a Mr. Lawson, that “the tortoises differed from the different islands, and that he could with certainty tell which island any one was brought (p. 351)”. His notes, however incomplete, do provide illustrating and accurate examples. For example, Darwin notes that three species of mockingbird occur on separate islands [Mimus trifasciatus on Floreana, M. parvulus on Isabela, and M. melanotis on Santiago and San Cristobal]. While he describes their forms as “highly characteristic of America,” he does not specifically identify the longtail mockingbird of Ecuador (M. longicaudatus) as an ancestral stock [a claim made by Constant (2006)]. This is the argument from derviation mentioned above—a cluster of closely related, but distinct endemic mockingbirds appears derivative of a mainland species with close geographical ties. Combined with the argument that biodistribution follows predictable patterns (those species that can’t survive sea passage don’t occur on oceanic islands, endemism is greatest in colonists with the least dispersal ability, the colonist species show structural affinity with their closest geographical coevals, etc.), the presence of these clusters of similar species on different islands suggests a colonization event followed by the differentiation into distinct species on each island—adaptive radiation. The deep sea passages and the length of the channels between the islands presents an obstacle for dispersal, and once established, the differentiated species prevent recolonization by closely related species on the other islands—competitive exclusion.
The islands are replete with examples. Darwin didn’t entirely miss the finches; he simply wasn’t systematic enough in his note-taking. Darwin noted the difficulty in identifying the finches, which lack distinctive plumage, due to the insensibly graduated beaks between, for example, the small beaked ground finch Geospiza parvula and the large beaked G. magnirostris. Such variation, with the underlying similarity, blurs the distinction between species and variety and exemplifies adaptive radiation. There are thirteen species of endemic finch in the Galapagos Islands, and all of them are descended from an original species closely related to Melanospiza richardsonii, of St. Lucia Island in the Caribbean. Similarly, though again Darwin lacked good notes, the distribution of tortoises provides an example of variation on the precipice of the species/variety distinction and adaptive radiation. Darwin reveled in the idea that the shapes and patterns of tortoise shells varied idiosyncratically, allowing a reasonably well-acquainted observer to determine the island of origin of a mature carapace. The tortoises are today all classified as subspecies of Geochelone elephantopus (of which 14 are classified, 11 surviving, and 1 with only one individual—lonesome George. Though Darwin’s classification differs, citing only two or three “species or races”). Galapagos tortoises come in three major morphological varieties: saddlebacks (on Espanola, Pinzon, Pinta, and Fernandina), with a raised carapace in front, the larger dome-shaped variety (Santa Cruz and Isabella), and intermediates which occur in both varieties (suggesting, perhaps, a reversion to an intermediate common ancestor?). Today, all of the Galapagos tortoises are thought to be derivative of a single species in Argentina, G. chiliensis. The different morphological types occupy different niches. The giant dome-shaped tortoises graze in the wet highlands, while the smaller saddleback tortoises feed on succulent cacti in the lower arid zone (the raised frontal carapace allows the tortoise to reach up to the cactus leaves). Tantalizingly (and missed by Darwin), Isabella island, with its five major volcanoes separated by lava desert, also has five distinct subspecies of dome-shaped tortoise (one on each volcano). If Darwin observed this, it would have become the golden goose of his writings on speciation and geographical separation.
Darwin noted the greater size of marine iguana (Amblyrhynchus cristatus) on Isabela Island, compared with San Cristobal, Santiago, and Floreana, and considered the possibility of different subspecies. Today marine iguanas have seven documented subspecies. Similarly, land iguanas (Conolophus subcristatus or pallidus) are now separated into two different species, Santa Fe having the endemic, larger, white-to-chocolate brown C. pallidus. This variation between the islands could be considered the early process of adaptive radiation analogous to what occurred between mockingbirds, scelasia trees/shrubs, and giant tortoises. Moreover, if Darwin had conducted a long-term study of the islands he might have observed the hybridization of land and marine iguanas on Santa Fe. During El Nino years, when marine populations plummet and terrestrial populations thrive, the ranges of land and marine iguanas overlap. Occasionally, large male marine iguanas copulate with smaller female land iguanas. Marine iguanas are black, with a broad snout. They feed on marine algae and they use their tall, flat tail to propel themselves forward with their legs held against their body like an alligator. To contrast, land iguanas are larger, yellow-orange, with a longer snout and round tail. They feed on cacti and live in burrows in the ground, never entering the water. There is absolutely no confusing one for the other. Hybrids appear more like a land iguana, with a long snout and dark vertical stripes. In Darwin’s day, marine and land iguanas were classified in a single genus (Amblyrhynchus) with no subspecies. The production of viable offspring between two closely related yet clearly defined species, with different lifestyles and diets, would have further chipped away at notions of the fixity of species.
Darwin also neglects to discuss the flightless cormorant (Nannopterum harrisi). The flightless cormorant is an endemic sea bird with webbed feet that feeds on fish and octopus underwater near the bottom within 100 meters of the shore. It is unique amongst cormorants in losing its ability to fly and retaining small vestigial wings (about 1/3 the size required for flight). Cormorants lack water-proof feathers, and they often spread their wings out in the wind to dry off. Vestigial structures are a hallmark of transmutation; they reveal an historical origin. Darwin might have also used the flightless cormorant to demonstrate the functional acuity of a structural intermediate between a flighted and flightless bird. Darwin could have argued, as scientists argue today, that a flighted cormorant arrived as a colonist on the islands. In its new conditions of life, perhaps due to a lack of predation allowing it to build nests accessible to a flightless bird, there was no longer any adaptive benefits to retaining wings. These just-so stories weren’t unknown to him, and vestigial structures are incomprehensible under the predominate theory of special creation. It’s seems likely that he simply didn’t notice them.
And Darwin certainly was remiss in hardly mentioning the lava lizards [his commentary is literally limited to “there is one small lizard belonging to a South American genus (Darwin 1839 p. 341)]. This endemic genus (Microlopus), besides being the subject of my own independent research project (see pages ##), has one endemic species each on seven different islands. Moreover, a comparative study would have been easy as they are extremely abundant and exhibit distinctive color patterns. One can only assume they narrowly missed (perhaps by virtue of an adept physiological color change mechanism) being Christened “Darwin’s lizards”.
In the introduction of The Origin of Species (1859), Darwin writes: “When on board H.M.S. ‘Beagle,’ as a naturalist, I was much struck with certain facts in the distribution of the organic beings inhabiting South America. These facts…seemed to throw some light on the origin of species—that mystery of mysteries.” One gets the idea, reading these words, that Darwin must have lumped the Galapagos into “South America” (a reasonable notion, given his insistence that the flora and fauna were entirely American in character). Undoubtedly, the antediluvian scene of the Galapagos, its large reptiles assuming the role of mammals, its closely related yet distinct birds inhabiting the different islands, its American character combined with its great novelty, put the germ of transmutation into the mind of a young Charles Darwin. But only by approaching the islands with a theoretical framework, collaborating with experts in other fields, and reinterpreting his findings could the evidence of evolution come to light. The young Darwin turned into the sage white-bearded Darwin through an insensibly graduated series of minor revelations—culminating in the revelation that he would lose priority to a young interloper named Alfred Russel Wallace if he didn’t hurry up and publish. The Galapagos represents an important chapter, amongst many, in the origin of evolutionary theory (albeit one deserving more than 27 pages).



June 22
Goodbye Ecuador

Goodbye Ecuador.