The cover slide of Michael Yuan’s talk at SICB 2018.
Convergent forms of anoles can be found across the Greater Antilles, with similar phenotypic and ecological morphs filling similar microhabitats from island to island. Anole ecomorphs are in part defined by the extent of arboreality, as most species in the Greater Antilles spend a lot of time in trees. Crandell et al. 2014 found arboreality to be associated with significant differences in claw characteristics in Costa Rica and Panama. In Greater Antillean anoles, similar research into claw morphology has yet to investigate if this relationship holds across ecomorphs. Michael Yaun, a PhD student in the Wang lab at UC Berkeley, set out to investigate the patterns of variation of claw morphology in the Greater Antillean anoles.
Anolis barbouri is shown as an outlier in a PCA. The flattened claws of this ground-dwelling anole are illustrated in black to the right.
Michael sampled 566 individuals, which included 55 species of anoles, all 6 ecomorphs, and another 8 species without any ecomorph designations. His results suggest that perch height and diameter produced differential effects on claw characteristics. Performance traits like toepad lamellae number and area were not correlated with claw height and length. Michael’s study uncovered only one anole that conformed to previous research: Anolis barbouri, the only truly terrestrial species in the data set, possessing flattened claws. Intriguingly, twig anoles have the most divergent claws, an inspiring result for future directions!
Photo by Andrea Westmoreland
Human-mediated range expansion is rapidly forming novel populations of anoles. The ancestry of these new populations typically traces back to a handful of individuals, and with repeated invasions the genetic history can be complex. These scenarios may be common in non-native populations of Anolis carolinensis, but what does the genetic history look like in such a system? In Sozos Michaelides’ talk at SICB 2018, he discussed his recently published findings.
Michaelides et al., 2017 tackled the question by inferring colonization history using mitochondrial haplotypes from Hawaiian Islands (Oahu, Hawaii, Maui, and Lanai) and some western Pacific islands (Guam, Palau, Saipan, Yap, and Rota). After genotyping 576 anoles, population genetic diversity and differentiation was assessed between native and non-native ranges. Results indicated geographically disparate haplotypes were identical (Hawaii to Brownsville, Texas), demonstrating that source populations may be from Texas or Louisiana. And a minimum of two introductions to Hawaii and Guam were uncovered, with subsequent within-population stepping-stone model colonization.
Overall, lower genetic diversity was found in non-native island populations as distance increased from the southeastern United States source population, and between the two archipelagos, genetic differentiation was high. Persistence of these non-native populations is not guaranteed because they are isolated, small in population size, and low in genetic diversity. It will be interesting to study the adaptive response of these introduced populations to stochastic climatic events!