Meeting Abstract
Convergent evolution is the evolution of similar phenotypes in distantly related taxa. It occurs at all biological scales, from genetics to ecology, and in all taxa. The availability of phylogenetic trees and advances in phylogenetic statistics have allowed for the development of methods to test for convergent evolution. Squamate reptiles (lizards and snakes) provide a rich collection of potential examples of convergent evolution, having evolved snake-like body shapes, dry adhesion, gliding, herbivory, and various other traits multiple times. Here, I quantify body shape for 636 species of primarily lizards and construct a phylomorphospace to test whether convergence in body shape has evolved in these various examples. I test for convergence by examining the degree of overlap among convergent taxa in the phylomorphospace and by examining the direction of evolution along convergent phylogenetic branches by comparing non-convergent ancestors and convergent descendants. I find evidence of convergence in body shape for snake-like taxa, gliding taxa, and sand-dwelling taxa. I find weaker evidence for body shape convergence in taxa that have evolved dry adhesion, and no evidence for body shape or size convergence in herbivorous taxa. My findings highlight that choice of traits used to test for convergent evolution affects whether convergence is found or not. For example, the evolution of a snake-like body is intimately related to body shape evolution, while the evolution of herbivory is not, although convergence of herbivores can be seen in skull and jaw shape. As approaches to identifying convergent evolution become more rigorous, researchers will be able to focus more on the functional and developmental mechanisms behind the convergence.
