Meeting Abstract
There is pressing urgency to understand how tropical ectotherms can behaviorally and physiologically respond to climate warming. Here we test whether basking behavior influences physiological trait divergence across dramatic climatic gradients in several species of lygosominid rainforest skinks from the Wet Tropics of northeastern Queensland, Australia. Using both phylogenetic and conventional analyses, we demonstrate that physiological traits exhibit contrasting divergence patterns. Whereas montane lizards were more cool tolerant than those from lower elevation in all taxa, basking species (Carlia and Lampropholis) were substantially more heat tolerant than the shade skinks (Gnypetoscincus and Saproscincus). Heat tolerance, however, remained otherwise static across steep thermal gradients. The optimal sprinting temperature and performance breadth were both inversely correlated with environmental temperature: We suggest that as environmental temperatures approach lethal limits, basking species and shade-dwellers alike reduce surface activity patterns, leading to tighter specialization to cooler environmental temperatures. These findings demonstrate that some physiological traits shifts concomitantly, whereas others shift (or remain inert) independently. This modularity in physiological evolution implies that responses to climate change can manifest in multiple independent directions, although it is unlikely that heat tolerance, the trait of most immediate importance to rising temperatures, can exhibit substantial shifts.
