Anole Annals

Over at The Lizard lab, Martin Whiting discusses a recent paper published in Biological Conservation on the conservation status of reptiles. Basically, a cast of thousands assessed a random sample of 16% of the world’s reptile species, categorizing them into the IUCN’s categories of conservation concern, which range from “least concerned” to “critically endangered” and, of course, “extinct.”

Martin nicely summarizes the paper in his post, but I’ll reprint his conclusion summary paragraph here: “59% of species were Least Concern, 5% were Near Threatened, 15% Threatened (Vulnerable, Endangered or Critically Endangered) and 21% were Data Deficient. To put this another way, one in five species are threatened with extinction and another one in five are data deficient. The paper identifies freshwater habitats, oceanic islands and tropical regions as containing the highest proportion of threatened species. Habitat loss and direct harvesting are two key threats to reptile populations and these are depicted in Figure 3 from the paper” (above).

Of course, from the AA perspective, the question is: what about anoles? The results were, to me at least, surprising. Of the 65 species surveyed, 29.3% were in one the three threatened categories, nearly twice as many as the global average! I would have guessed the opposite–most anoles seem to being doing reasonably well. But, then I rationalized, it must be the mainland anoles, because Caribbean anoles are generally doing fine. Again wrong! 11/28 (39%) Caribbean anoles are in these categories (including the only two “critically endangered species, A. juangundlachi (known from one specimen, if I recall correctly) and A. roosevelti), compared to 8/37 (22%) for mainland species. One non-surprise is that all 10 “data deficient” species are from the mainland; however, even when they are removed, the percentage threatened in the mainland (30%) is still less than in the Caribbean. At least for the Caribbean species, the biggest predictor seems to be range size, as all threatened species either have small distributions or occur on small islands. I am less familiar with some of the mainland species, but think the same may be true for those. I’ll append the list below.

One last note: the paper truly has an extraordinary number of authors who contributed to this massive compilation. One amusing consequence is that the list of authors’ affiliations at the start of the paper is three pages long!

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Based on a long-standing program of field exploration initiated by the Smithsonian’s National Museum of Natural History and the University of Guyana, with further support from the American Museum of Natural History and the Royal Ontario Museum, a distinguished cast of authors, each with extensive experience in Guyana, has just published this enormous and useful monograph. Part of the abstract is appended below, but more importantly you may be wondering, just which anoles occur in Guyana? The answer is that there are at least five native species (auratus, fuscoauratus, ortonii, planiceps, and punctatus). They note, as well, that chrysolepis is reported to occur in Guyana as well, but all chrysolepis group specimens they examined turned out to be planiceps.

In addition, at least one Lesser Antillean species occurs in the cities of Georgetown and Kartabo. These invaders have been identified as both A. extremus from Barbados or A. aeneus from Grenada and the Grenadines, but the authors were unable to find any reliable morphological characters that could distinguish the two species, and thus could come to no conclusion about which species, or both, occur in several cities in Guyana, though they did note that Ernest Williams had identified many of the specimens in museums from Guyana as A. aeneus, as good a reason as any to attribute them to that species. The authors conclude “Clearly, the taxonomic status of Anolis aeneus versus Anolis extremus needs further investigation, both in areas where they occur in the West Indies and where they have been introduced on islands and the mainland of South America.”

Honorary anole friend Polychrus marmoratus also occurs in Guyana and is pictured above.

The first half of the two-page abstract:

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