Professor of Biology and Director of the Living Earth Collaborative at Washington University in Saint Louis. I've spent my entire professional career studying anoles and have discovered that the more I learn about anoles, the more I realize I don't know.
"The rediscovery of a missing anole"
Everyone’s favorite anole, A. proboscis, is featured in an article in the most recent issue of Lacerta. The article is chockful of beautiful pictures, such as the one above, but does have one shortcoming, at least for most of AA’s readers: it’s in Dutch! However, thanks to Harvard undergrad Jelle Zijlstra, we can provide a translation of at least part of the text.
Jelle writes:
Wade Davis, explorer extraordinaire, made his name as a graduate student at Harvard by proposing not only that Haitian zombies were real, but that they were created by ingesting concoctions that include tetrodotoxin, the toxin in pufferfish and the infamous Japanese delicacy, fugu. When the victim recovers (if he does), he believes he has become a zombie, and this belief is then taken advantage of by the voodoo priest.
Davis first reported his hypothesis, controversial to this day, in a 1983 paper. In that paper, he reports the results of three expeditions to Haiti, in which he documented the preparation of five separate zombie potions in four different villages. The process by which the potion is created is an elaborate and intricate ceremony, which the gentle reader may learn about by reading the aforementioned paper. For our purposes here, the interesting issue is the ingredients that go into the potion.
The website anolissen.nl has a collection of reasonably high quality anole videos, including one of Terry Ord’s behavior research, featured yesterday, as well as A. allisoni from Cuba fighting; many Cuban species displaying, including A. allogus (or was it A. ahli?) and A. mestrei; A. cuvieri displaying; A. punctatus displaying; a green anole (who can identify it?) eating a butterfly; and a bonus outgroup track of Polychrus acutirostris, as well as others.
The Puerto Rican grass-bush anole, A. pulchellus, displaying. Recent research indicates that this and some other, but not all, anole species time their displays to occur when the wind isn't blowing. Photo @ Rich Glor.
Successful communication requires that a message be detected by the intended receiver. One trick animals have when they communicate is to use signals that stand out against the background, so that they are more easily detected, such as waving light colored structures against a dark background, or making high-pitched calls when surrounded by low-pitched sounds. But what happens when the background isn’t constant? Just as we tend to talk when conversation partners are quiet, animals would be expected to signal at those times when their signals contrast to the greatest extent with the background and thus are most detectable. Reasonable as this hypothesis is, it has only been tested once, in a study which showed that lab monkeys vocalized in silent periods between bursts of machine generated white noise.
Anoles signal primarily in two ways, by moving their head and body up-and-down and by extending their dewlaps. With regard to the former, research has shown that headbobs are effective at catching the attention of other lizards because the rapid and jerky movements contrast strongly with motion in the background. However, this is only true when, in fact, the background—that is, the vegetation and other stuff behind the lizard—isn’t moving very much. When the wind is blowing and leaves and branches are swaying back and forth, headbobs should be more difficult to detect. Consequently, on a windy day, a savvy anole should time its headbobs to occur when the wind is not blowing.
And that’s just what they do—at least some of them.
Dan Warner and Aaron Reedy caught this male A. sagrei in September of last year on a spoil island at Tomoka State Park in Ormond Beach, FL.
Anolis chlorocyanus (photo @ Rich Glor). Anolis chlorocyanus occurs north of Mertens' Line, A. coelestinus to the south. Map on right (from Glor and Warren, 2011) illustrates that suitable conditions for both species occur in the range of the other species (the warmer the color, the more suitable the area).
Many sets of closely related species exhibit a geographic distribution in which species only come into contact at their range border, with one species replacing another across the geographic landscape. Such a “parapatric” distribution could be explained in many ways, such as:
1. The species are adapted to different environments, and their distributions reflect geographic differences in environmental conditions;
2. The environment does not change geographically, but the species are so ecologically similar that neither is able to displace the other from its current range;
3. The species are not reproductively isolated; when they come into contact, they interbreed, thus preventing coexistence;
4. The species are newly-arisen, and have not yet expanded their ranges into sympatry, or one species has not yet displaced the other completely.
A case in point are the large green anoles of Hispaniola, Anolis chlorocyanus and A. coelestinus. Except for their dewlap, these two trunk-crown species are nearly identical in morphology, and they also occupy similar structural habitats. Yet, A. coelestinus occurs only in the southern peninsula, whereas A. chlorocyanus occurs throughout the rest of the island.
Anolis princeps sawing logs in Ecuador.
There have been a number of posts recently discussing various aspects of the sleeping biology of anoles (e.g., here, here, and here). Anoles spend 1/3 to 1/2 of their lives asleep, so it is not surprising that there is a small cottage industry of research papers describing where they sleep, in what position, and with whom. The most recent addition to this genre is a very nice paper on A. uniformis in Mexico, which reveals that this species is typical in sleeping on leaves with its body in line with the long axis of the leaf. The paper includes a brief, but thorough review of the literature on anole sleeping and thus is a good entrée to the literature.
A somewhat less brief review of the literature might go something like this
Evolution of species in a two-dimensional morphospace. Axes are from a principal components analysis of morphology; symbols represent different ecomorph classes.
Over on the Phytools blog, anole biologist and comparative methods guru Liam Revell provides a program to visualize the evolution of traits in multivariate space, termed a “phylomorphospace.” This method plots species’ values and connects the points to portray their phylogenetic relationships. Most imporantly, the example he uses is none other than Greater Antillean anole ecomorphs, using a figure developed by Luke Mahler and pictured above. The diagram above illustrates convergence of the ecomorphs by showing that members of the same ecomorph class occur in the same parts of morphological space, even though many members of each ecomorph are not closely related to each other. Each large dot represents an extant ecomorph and the color indicates ecomorph class; small dots are internal nodes of the phylogeny. Admittedly, these spaghetti-grams can be hard to follow for large phylogenies, but they do give a sense of how traits have evolved and the extent to which convergence occurs.
Anolis gemmosus from Mindo, Ecuador
One of the reasons that spot-lighting for anoles at nights works so well is that many anole species adopt a lighter color in the evening. This was first noted by Reverend Lockwood in an article in the American Naturalist in 1876 who noted that his captive anoles were usually brown during the day, even when on a green leaf, and were green at night, even when sleeping on brown surfaces. He concluded (p.13): “The belief that the color of the contiguous object is mimicked for the sake of protection is, I think, not confirmed by the observed facts. The truth is that in this matter of animals enjoying life there is a higher law than that of mere intention. I shall call it the law of spontaneous expression, which has its base in another law, to wit, that a joy unuttered is a sense repressed. Why should green be the favorite night-gown of our sleeping Anolis? I timidly venture the suggestion that it is because the animal is disposing itself for the luxury of sleep, its color changes being the utterances of its emotions . . . Whether it be the expression of enjoyment of repose, comfort, or emotional joy, the highest manifestation is its display of green.”
We’ll all give a big hand to whomever provides the best caption for this photo. While you’re ruminating about something clever, notice that this adult male Anolis sagrei, collected from an introduced population in Taiwan and reported on here, is quite fat and sassy (or at least fat). Clearly, the extra appendage did it no harm. Who knows, maybe it even helped! Many anoles with three legs have been collected over the years (more examples always welcome). The existence of five-legged anoles means that it is now statistically possible to examine the relationship between limb number and sprint speed. Stay tuned.
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