Walking or hanging: the role of habitat use for body shape evolution in lacertid lizards.

The article investigates how habitat use influences body shape evolution in lacertid lizards, focusing on differences between ground-dwelling and climbing species. Using phylogenetic comparative analyses of 186 species and seven morphological traits, the study finds that habitat use significantly affects head shape evolution, with climbing species exhibiting flatter heads compared to ground-dwellers, which have taller, more robust heads. In contrast, limb morphology shows limited differentiation; only forelimb length differs significantly, with climbers having longer forelimbs, while hindlimb length and forelimb-to-hindlimb ratios do not vary notably between habitats. Ancestral state reconstruction suggests that lacertids likely evolved from a climbing ancestor, with multiple transitions to ground-dwelling habits. Despite adaptive differences in head morphology, no significant convergent evolution was detected in either head or limb traits within habitat groups, indicating complex and trait-specific evolutionary responses to habitat use in this lizard family.