Morphological Diversification in Three Southern African Radiations of Lizards

Document Type


Publication Date



Morphological diversification within clades can be the result of adaptive or neutral processes. High rates of morphological diversification are often inferred to be evidence of adaptive radiation. However older clades may show more species, or greater morphological diversity, than younger ones and hence bias interpretations. Hence these hypotheses must first be examined prior to assessing the ‘adaptive’ nature of radiations. However, differentiating among the multitude of potential causes for these mechanisms is a continuing challenge. Recently developed methods allow for tests of these hypotheses and hence the precise mechanisms that cause diversification patterns in lineages can be distinguished. Here we examine morphological diversification in three southern African lizard radiations. These species are often syntopic, hence there is likely to be an imprint of habitat on morphology. In this study we examine whether the morphological diversification in southern African lizards is due to neutral processes (drift), or reflects the effects of selection. We quantified morphological variation via 12 measures of the cranial and post-cranial skeleton in 74 species from lizards in the families Scincidae, Cordylidae, and Lacertidae. We compare morphological diversification within and among each radiation. We summarized the patterns of covariation using common principal components analysis, random skewers, and mantel tests, based on independent contrasts. Our analyses rejected neutral patterns of diversification. However, diversification is also idiosyncratic among families.


Society for Integrative and Comparative Biology Annual Meeting (SICB)


Salt Lake City, UT