@ARTICLE{TreeBASE2Ref17200, author = {Liam Revell and Michele A. Johnson and J. A. S. Ii and Jason J. Kolbe and Jonathan B. Losos}, title = {A phylogenetic test for adaptive convergence in rock-dwelling lizards}, year = {2007}, keywords = {}, doi = {}, url = {}, pmid = {}, journal = {Evolution}, volume = {}, number = {}, pages = {}, abstract = {Phenotypic similarity of species occupying similar habitats has long been taken as strong evidence of adaptation, but this approach implicitly assumes that similarity is evolutionarily derived. However, even derived similarities may not represent convergent adaptation if the similarities did not evolve as a result of the same selection pressures; an alternative possibility is that the similar features evolved for different reasons, but subsequently allowed the species to occupy the same habitat, in which case the convergence would be the result of exaptation. Many lizard lineages have evolved to occupy vertical rock surfaces, a habitat that places strong functional and ecological demands on lizards. We examined four clades in which species that use vertical rock surfaces exhibit long hindlimbs and flattened bodies. Morphological change on the phylogenetic branches leading to the rock-dwelling species in the four clades differed from change on other branches of the phylogeny; rock-dwelling lizards tended to have overall longer limbs and flatter heads. Examination of particular characters revealed several different patterns of evolutionary change. Rock-dwelling lizards exhibited similarities in head depth as a result of both adaptation and exaptation. Moreover, even though rock-dwelling species did not have longer limbs than non-rock-dwellers, limb length nonetheless evolved in the same direction relative to non-rock-dwelling sister taxa in most clades; clade-level differences in limb length, however, led to an overall lack of difference between rock- and non-rock-dwelling lizards. These results indicate that evolutionary change in the same direction in independent lineages does not necessarily produce convergence, and that the existence of similar advantageous structures among species independently occupying the same environment may not indicate adaptation.} }

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