Anole Annals

Photo by Claus Meyer at http://www.nationalgeographicstock.com/

For many years, the South American lizard genus Polychrus has been considered the closest extant outgroup to Anolis.  In light of this phylogenetic position, the authors of a new report on the life history of Polychrus acutirostris note that “a comprehensive understanding of Polychrus might help clarify possible ecological factors related to the radiation of anoline lizards as well as to infer the existence of niche conservatism or dietary shifts related to the origin of this large lizard radiation” (Garda et al. 2012).

Members of Polychrus are superficially similar to Anolis, and are mostly medium sized arboreal and diurnal lizards.  However, Polychrus also differs from Anolis in both conspicuous (e.g., lack of toepads) and somewhat less conspicuous ways (e.g., its tendency to produce single clutches of multiple eggs, versus multiple one egg clutches in Anolis).  In their report, Garda et al. (2012) compare populations of Polychrus acutirostris found in two different Brazilian habitats to test whether size of eggs and clutch size, reproductive seasonality, diet, and size of reproductive adults varies among populations in the manner predicted by life history theory.  Although recent work makes Polychrus‘s position as the outgroup to Anolis less certain than it once was (Schulte et al. 2003, Townsend et al. 2011, and this previous AA post), we still have much to learn from the type of comparative studies that Garda et al. have implemented.

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Anolis concolor from mangroves on San Andres island. Photo by Lee Fitzgerald

Almost all Caribbean anoles are descendants from a single colonizing species, whose descendants now occupy all of the Greater Antilles, the Lesser Antilles south through Dominica, and many other islands. Almost all of the remaining species are members of the roquet clade, occupying the southern Lesser Antilles and descended from a South American colonist. As we all know, these species have been extensively studied.

But colonization of Caribbean islands has occurred more than just these two times. Some other islands have been colonized by different colonists. None of these invasions has led to much in the way of evolutionary radiation and these species–in each case the only anole on the islands they occupy–have been little studied. We’ve previously discussed one such colonization, A. lineatus on Aruba and Curaçao. In addition, islands in the Pacific (yes, the Pacific!) have twice been colonized, leading to A. agassizi on little known Malpelo and A. townsendi on Cocos Island (incidentally, the island said to have beeen the inspiration for Isla Nublar in Jurassic Park).

And, finally, there are the presumed sister taxa, A. pinchoti and A. concolor, on the Colombian islands of Providencia and San Andrés. A smidgeon of research has been conducted previously on their ecology, and now a new paper in the South American Journal of Herpetology has examined their morphology. Calderón-Espinosa and Barragán Forero measured museum specimens of these species and compared them to published data on a variety of other Caribbean anoles. They found that neither species is a good match for any of the Greater Antillean ecomorphs, but that they are most similar to trunk-ground or trunk-crown anoles. By comparison, anoles of the Lesser Antilles are also most similar to these two ecomorphs. Anolis concolor attains an intermediate body size, similar to Lesser Antillean species that occupy islands on which they are no other anole species. By contrast, A. pinchoti is smaller and more similar to the smaller Lesser Antillean species on two-species islands.

Anoles are renowned for their convergent evolution. Further comparison of the many cases in which anoles have colonized relatively small islands should prove interesting.

M. L. Calderón-Espinosa and A. Barragán Forero (2011). Morphological Diversification in Solitary Endemic Anoles: Anolis concolor and Anolis pinchoti from San Andrés and Providence Islands, Colombia South American Journal of Herpetology

Anolis cristatellus from mesic habitats. Photo by Manuel Leal.

For obvious reasons, there is great concern about how species will cope with climate change–as the world gets hotter, will species be able to survive? Many studies have taken a macroscopic view, examining the geographic distribution of a species to divine what its temperature tolerances are and then projecting where it will be able to occur in the future. Although such approaches are useful as a first pass, direct study of the physiology of species is a much more informative way of determining how a species will be affected. An excellent example of just this approach was published recently by Gunderson and Leal in Functional Ecology (pdf here).

Mesic and xeric habitats. Photos courtesy Alex Gunderson (left) and Manuel Leal (right)

The authors studied the Puerto Rican crested anole, A. cristatellus, which occurs throughout Puerto Rico and the Virgin Islands. They focused on comparing populations living in cooler, wetter (mesic) habitats versus those living in hotter, drier (xeric) places. They found that in the field, mesic populations had an average body temperature of  about 29 C, whereas xeric populations averaged 32.5 C. However, using copper models as described in previous posts, the authors determined that a lizard randomly placed in a mesic habitat would have a temperature of about 29 C, whereas the random xeric lizard would be 33.5. In other words, the lizards are not thermoregulating in the mesic forest (lizards and randomly placed copper models have the same temperature), but they are actively altering their habitat use in the xeric areas to use cooler spots and thus keep their temperature lower than if they were sitting in random spots. In support of this conclusion, the mesic lizards were in the sun about as much as expected, but the xeric lizards were in the sun less often than predicted.

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In the herpetology community (i.e., reptile and amphibian aficionados), The World Congress of Herpetology (WCH) is a big deal. In essence, it is a very large scientific conference, held every 3-5 years, uniting local herpetology societies from around the world.

“I wouldn’t miss WCH for anything!”– J.B. Losos

As the WCH mission statement says, “the objectives of the Congress are to promote international interest, collaboration and co-operation in herpetology”; in laymen’s terms means we herpetologists get together to talk about our research in formal meeting rooms, as well as informally in the pub over a beer or two.

This year the 7th World Herp Congress will be held in Vancouver (8-14 August 2012). [Incidentally, a small typing error in google brought me to the 11th World Harp Congress, happening just a few weeks earlier in the same place!]

There will be 15 presentations and 8 posters focussing on our beloved anoles! Including presentations from some of your favourite Anole Annals contributors. A run down of the anole content is after the fold.

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