Meeting Abstract

44.5  Monday, Jan. 5  LIZARD BODY FORM EVOLUTION AS ADAPTATIONS FOR OPTIMAL LOCOMOTION IN DIFFERENT HABITATS PIENAAR, J*; SCALES, J. A. ; WIENS, J. J. ; BUTLER, M. A. ; University of Hawaii jasonpienaar@gmail.com

We hypothesize that locomotion requirements through a given habitat are a major determinant of body form evolution amongst lizards. To test this, we utilize a large comparative data set (n=217) that includes representatives from a variety of habitats as well as measures of snout-vent length, tail length, fore-limb length, and hind-limb length for each species. A supertree phylogeny with branch lengths also exists for these species, allowing us to control for phylogenetic effects and more importantly, phylogenetic inertia. By using both Brownian-Motion (BM) based comparative methods and ones that model trait evolution as a stochastic Ornstein-Uhlenbeck (OU) process with a deterministic tendency to move towards fixed optimal states, we are able to compare a model of trait evolution through random drift to one of adaptation and subsequent maintenance of traits at habitat specific optima. For the adaptive models, we test various habitat categorizations as potential predictors of trait evolution. We find that for all traits, the OU-based models with sub-subterranean, terrestrial, dense-grass and an arboreal category as predictor variables, by-far outperform the BM based models. For snout-vent and tail lengths we show that current observed trait values are strongly influenced by both adaptation to specific niche optima and phylogenetic inertia. Fore and hind limb lengths also exhibit strong adaptation but are much less influenced by inertia. Finally, we obtain estimates of the optimal trait values in each of the selective niches that we would expect in the absence of phylogenetic inertia, which may aid future studies of optimal lizard body forms for given locomotor requirements