Meeting Abstract

25.2  Friday, Jan. 4  Does thermal specialization accompany environmental differentiation in a diverse clade of Caribbean Anolis lizards? MUNOZ, MM*; STIMOLA, MA; LANDESTOY, MA; CONOVER, A; RODRIGUEZ, A; ALGAR, AC; LOSOS, JB; Harvard University; Columbia University; Sociedad Ornitologica de la Hispaniola; Stuyvesant High School; University of California, Davis; University of Nottingham; Harvard University mmunoz@oeb.harvard.edu

Despite lacking physiological heating and cooling, vertebrate ecotherms can be found across a wide spectrum of thermal environments. The degree to which ectotherm diversification along thermal gradients is accompanied by evolution in thermal physiology remains a pervasive question in evolutionary biology. The adaptive radiation of Anolis Caribbean lizards in the Greater Antilles has been most often studied along a single axis – morphological and behavioral adaptation to microhabitat (i.e., the ‘ecomorphs’). However, most of the species richness of these anoles occurs through within-ecomorph radiations along a separate axis of specialization – thermal preferences along macrohabitat gradients. The cybotoids are a clade of Hispaniolan trunk-ground anoles that present the most extreme case of radiation along macrohabitat gradients. Members of this group are found from sea level to almost 3,000 meters and span a wide gamut of thermal environments. In this study we use environmental niche modeling (ENM) to quantify diversification in the thermal niche among seven species of Dominican cybotoids. We employ a phylogenetic framework to measure the extent to which diversification in the thermal environment has been accompanied by differentiation in the thermal sensitivity of three metrics – the critical thermal minimum (CTmin), critical thermal maximum (CTmax), and the mean field-active body temperature (Tb). We find that environmental diversification is accompanied by thermal specialization in some, but not all, physiological traits, and likely reflects tradeoffs between optimal performance and performance breadth in variable thermal environments.