3.3 Wednesday, Jan. 4 A comparison of heat and cold tolerance among closely related anoles from different thermal environments. STIMOLA, M.*; MUñOZ, M.M.; LANDESTOY, M.A.; CONOVER, A.; RODRIGUEZ, A.J.; LOSOS, J.B.; Columbia University; Harvard University; University of California, Davis; Harvard University email@example.com
The adaptive radiation of Anolis lizards in the Greater Antilles (Cuba, Hispaniola, Jamaica, and Puerto Rico) is often studied in the context of convergence in morphological adaptation to different microhabitats. However, anoles on these islands have also diversified to occupy a broad range of thermal habitats. In Hispaniola, a single clade of trunk- and ground-dwelling anoles, termed the cybotoids, has diversified to occupy a broad range of thermal habitats. Some species in this clade are restricted to cool highland forests or are exclusively lowland species, while others are found throughout the range of island habitats. Sensitivity to low temperatures has been shown to vary in anoles depending on habitat, although the same is not always true for heat tolerance. Here we tested the hypothesis that temperature tolerance in this closely related group of anoles is correlated with environmental temperature. Specifically, we predicted that highland species have the greatest cold tolerance, but that heat tolerance would be comparable among all populations. The widespread species, Anolis cybotes, was predicted to have the broadest tolerance range relative to regional endemics. We compared field-measured thermal tolerances to heating and cooling with GIS-based estimates of thermal environment. We found that while species in cooler environments have correspondingly greater thermal tolerance to freezing, those found in hotter environments do not possess greater tolerance to heating. Consequently, the high elevation species, though more restricted in altitudinal range than most of the other cybotoids, have the broadest thermal tolerances. We examine these measures of thermal tolerance in the context of the cybotoid phylogenetic history, habitat variation, and altitudinal range.