Author: Jonathan Losos Page 92 of 130

One of the brown anole males in the McMann and Paterson study. Photo by Stephen McMann.

Anole Annals readers know otherwise, but many people consider lizards to be simpletons, with nary a thought in their head. But that’s mistaken–it’s salamanders that are the truly stupid ones (sorry for the tangential ad hominem). Lizards have more going on upstairs than people realize. Sure, they’re not the sharpest knife in the drawer, but they’re no dummies, either.
Case in point: lizards are able to recognize and differentiate among other lizards. This conclusion, which has now been demonstrated a number of times, was reinforced by a recent paper by McMann and Paterson in Herpetological Conservation and Biology. They set out to test whether  brown anoles react differently when confronted with a neighbor than when confronted with a lizard that lives farther away and that, presumably, the lizard has not interacted with in the past. This is a test of the phenomenon termed “dear enemy,” the idea that neighbors get to know each other and come to a mutual coexistence in which, when they encounter each other, they go through perfunctory displays, but don’ t get all riled up, because they’ve already been through all of that before. The dear enemy phenomenon has been demonstrated previously in a variety of other lizards. Indeed, these authors have demonstrated it before with brown anoles, but that work was conducted in experimental arenas. This time, the authors wanted to see what happened when the research was conducted in nature, in animals’ own territories. To do this, they presented territorial males with another lizard enclosed within a small cage.

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We’re just wrapping up a few last posts from last week’s World Congress of Herpetology in Vancouver. In a tour de force, Laura Rubio-Rocha presented two posters, side-by-side, in the first night’s session. We’ve already discussed her doctoral work on geographic variation in adaptation to different climates in A. carolinensis; here I briefly mention her poster on a high elevation Colombian anole that exhibits year-round reproduction in an environment in which there are two rainy seasons. This interesting study was recently published; you can learn more about it in our previous post on that paper.

A sampling of the anoles examined by Emma Sherratt

The World Congress called on Emma Sherratt to serve as the closer, presenting the last talk on the last day of the meeting. The choice proved brilliant, as she sent the audience off to the banquet in high spirits with a captivating report on her examination of 30+ specimens of amber-encased anoles. Emma has already wowed us with  the images and videos she produces by micro-CT scanning; needless to say, the audience was amazed. Preliminary analyses suggest that multiple species are present in the sample (only one amber anole has been described in the scientific literature), and several of the types may match present-day ecomorphs. Her abstract:

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Travis Ingram reported on a new method he devised to test whether the anole radiations on the Greater Antilles are more similar than might be expected to occur by chance. We all know that each island has experienced its own radiation, producing more or less the same set of ecomorphs. However, some islands have more ecomorphs than others (Jamaica: 4; Cuba, Hispaniola: 6). In addition, there are non-ecomorph species on the larger islands. It is always possible that it is just a coincidence that the same types have evolved on multiple islands. After all, given large enough evolutionary radiations, one would expect the same morphology to evolve by chance on multiple islands. Travis developed a method to test this hypothesis, and found that, indeed, the Greater Antillean radiations are more similar in morphology than would be expected by random evolutionary change. Read all about it in the abstract:

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Sebastian Lotzkat presented a fascinating talk on geographic variation, both morphological and genetic, in Panamanian reptiles, emphasizing the highlands of western Panama. Although he discussed a wide range of species, he spent an appropriately large amount of time focusing on anoles, which if I recall correctly, he termed his favorites. To cut to the chase, he’s found very large amounts of variation in almost every species examined, including in some cases dividing species into several new species. Some of this work has already been chronicled in AA, and another paper will soon be reported on, but apparently there is a lot more yet to come. Read the abstract below the fold.

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Anole brains. For scale, the partial coin is an American penny.

A pair of talks from Duke University took different approaches to examining anole smarts. Recently minted Ph.D. Brian Powell reported on his examination of the brain size and composition of different anole species. Brian reasoned that anoles living in different habitats would evolve differences in brain structure corresponding to the different challenges they faced, and thus that species that use the same habitat should have converged on brain morphology. However, results failed to support this hypothesis and instead indicated that the size of different brain components evolves in concert. More details below.

The three species that have demonstrated behavioral flexibility in the lab. Sure wish I could remember what the third point was

Later in the meeting, Manuel Leal reported on the cognitive flexibility of several anole species. Previous work has shown that A. evermanni is not only adept at solving novel problems, but can reverse previously learned patterns so as to ignore the stimulus that previously was rewarded and instead respond to a stimulus that previously hadn’t been rewarded. Leal has now extended that work to show that two other anoles can do the same. He then went on to test how adept anoles are at telling apart two similar patterns. He found, surprisingly, that they could tell very different patterns apart, but did not seem to be able to distinguish more similar patterns. Leal concluded by wondering whether minor differences in signals are detectable by receivers, which is an underlying assumption of many studies of sexual selection and communication. Manuel’s abstract is below the fold as well, although he went off-script in much of the talk he presented.

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