Comparative evolution of an archetypal adaptive radiation: innovation and opportunity in Anolis lizards

Adaptive radiation is a widely recognized pattern of evolution wherein substantial phenotypic change accompanies rapid speciation. Adaptive radiation may be triggered by environmental opportunities resulting from dispersal to new areas or via the evolution of traits, called key innovations, that allow invasion of new niches. Species sampling is a known source of bias in many comparative analyses, yet classic adaptive radiations have not been studied comparatively with comprehensively sampled phylogenies. In this study we use unprecedented comprehensive phylogenetic sampling of Anolis lizard species to examine comparative evolution in this well-studied adaptive radiation. We compare adaptive radiation models within Anolis and in the Anolis clade and a potential sister lineage, the Corytophanidae. We find evidence for island (i.e., opportunity) effects and no evidence for trait (i.e., key innovation) effects causing accelerated phenotypic evolution within Anolis. However,
island effects ...