Staniel Cay is one of the quaint Caribbean backwaters, populated by yachtsmen, expats, scalawags, locals and…scientists. For more than 30 years, Tom Schoener, David Spiller and associates have worked here, producing a series of textbook studies on food web ecology (most recently here).
Having finished our work in Marsh Harbour, we have relocated to Staniel, marking a return for me after a 19 year absence. As our plane wended its way down the Exuma
- Headin’ south down the Exumas.
chain, the memories of my previous visits and their results came flooding back. While a graduate student in the 80’s, I read Schoener and Schoener’s 1983 Nature paper reporting the results of introductions of brown anoles (A. sagrei) to very small islands (approx. the size of a baseball diamond) around Staniel Cay. S&S, noting that islands of this size do not normally harbor anoles, decided to introduce lizards to watch the populations wither away, and thus learn something about the process of extinction. But to their surprise, the populations did not go quietly into the night. Instead, they thrived and some downright exploded in numbers, one island going from 10 introduced lizards to 98 the next year.
At the time I read this work, I was studying how different species of anoles have adapted to using different diameter surfaces: anoles on broad surfaces evolve long limbs (e.g., trunk-ground anoles), whereas those that use narrow surfaces evolve short limbs. I saw the S&S study as an inadvertent test of the hypothesis that populations adapt to using different surfaces. Surely, the islands S&S used must vary in available vegetation, and if perch diameter is such a strong selective force, we might expect the populations to adapt by evolving different limb lengths. Of course, a big unknown (back then) was whether 14 years was enough time for natural selection to produce evolutionary divergence.
You can imagine my delight when I explained my reasoning to Schoener, and his response was that it was a great idea and that I should come to Staniel to find out. Long story short, I got a postdoctoral position at UC-Davis and, two years after our initial discussion, I joined Schoener and Spiller at Staniel for a five-week jaunt.
It turned out to be a terrible year for lizard work. The weather was warm, breezy, and dry—nice for tourists, but not for lizards, who hunker down in such conditions to avoid dehydrating. The result was that the work progressed slowly. As I caught lizards, I measured their limb lengths. Curious as to how the data were shaping up, and lacking any graph paper (much less the money to buy what were then outrageously expensive and heavy portable computers), I created my own grids and plotted the data points.
As far as I could tell, there was no trend in the data. For that reason, I did not hurry to analyze the results when I returned home—why waste my time? But eventually I did, and to my amazement, a significant result emerged: lizards in populations that used narrow surfaces had shorter legs than ones using broader surfaces. And this after only 14 years! We wrote a paper suggesting that this might be an example of rapid adaptive evolution, demonstrated by an experiment in nature. We did note, however, that another possibility—interesting in its own right—was that our findings were the result of phenotypic plasticity, lizards growing up using broader surfaces simply growing longer legs than lizards that grow on narrower surfaces (see discussion of this topic here).
The paper was accepted by Nature and slated for publication in early May, 1997. A week or so before that, I left for my first field trip to Marsh Harbour (to which I have returned every year since). Literally as I was closing my office door, I decided that I should leave contact information in case anyone needed me while I was gone. When I arrived in Marsh Harbour, I settled into a quaint, if dimly lit, rental unit which had a kitchenette and TV, but no phone. At the end of our seventh day of field work, I returned to my room, only to summoned by the property’s owner, who announced—his opinion of me clearly higher than when I left that morning—that the New York Times was trying to reach me. The next day I came back to messages from USA Today and ABC News, which wanted to send a crew down to film us in the field, and the following day the Boston Globe.
Why all this attention? It turned out that the Nature PR folks had put out their weekly press release and had featured our work, saying—I kid you not—“this may be the most important scientific work since Darwin visited the Galápagos.” Some of the press even parroted that line in their reports. In the end, ABC did not send out a film crew but did report the story, which also ran on the front page of the New York Times and was prominently featured in many other papers. Whether the paper deserved the hype or not (and for the record, I think it ranks closer to Darwin’s stop in the Cocos Islands), the outsized attention had an enormously positive effect on my career.
So, it is with these remembrances and a few others (giant flying cockroaches!) that I returned to Staniel. With a great group of collaborators led by Rob Pringle and Todd Palmer, we’re setting up an experiment to look at ecological and evolutionary consequences of interactions between brown anoles, Bahamian green anoles (A. smaragdinus), and curly-tailed lizards (Leiocephalus carinatus). The work is a logical follow-on to our studies in Abaco, but adding the wrinkle of studying interactions between two competitors, the anoles, and a predator (the curly). The experimental design is to see how brown anoles are affected by the presence or greens, curlies, or both, and to monitor down-web ecosystem consequences of such interactions.
It turns out that I remember the weather all too well. Again, it’s hot, dry and windy. But what I didn’t remember is that the islands here, in comparison to Abaco, are much more thickly vegetated. Moreover, for reasons yet undetermined, the brown anoles here are much more skittish than their Abaconian counterparts. One of the team, Jason Kolbe, had asked why the number of lizards measured per island for our Nature paper was relatively low. I now remember quite clearly why: the three way combination of bad weather, skittish lizards, and thick scrub makes brown anole wrangling a much greater challenge than elsewhere. The result is that, a week in, we’re in a mad dash to catch enough lizards on our 16 islands to get decent sample sizes before we start the experiment. As with our work in Abaco, we’re x-raying, scanning, and weighing the little fellows before returning them right back where we got them.
As for Staniel, it’s still a sleepy outpost, but times, they are a’changin’. Internet is now available, at least in some places, and there’s a huge building boom. Money seems to
- The M/V Copasetic.
be everywhere, especially right next door, where the largest yacht I have ever seen is moored. The owner invented—so the locals say—the transdermal patch. True or not, he seems like a nice guy and is letting us look for lizards on his property, even if he does still wonder whether we’re DEA agents.
With luck, we’ll capture enough lizards in the next 10 days to get our experiment rolling, and then we’ll let nature take its course.
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chipojolab
Are you positive that the lizards are more difficult to catch or is age and slower reflex part of the problem? I have not had the privilege to visit Staniel Cay, however, based on what other people working on “similar” projects in the general vicinity of Staniel Cay have published, they seem to be able to catch a LOT of lizards.
Gerrut Norval
Best of luck!