Morphological diversification of Mediterranean anurans: the roles of evolutionary history and climate

Abstract

Abstract Investigation of the ecological and evolutionary mechanisms governing the origin and diversification of species requires integrative approaches that often have to accommodate strong discordance among datasets. A common source of conflict is the combination of morphological and molecular characters with different evolutionary rates. Resolution of these discordances is crucial to assess the relative roles of different processes in generating and maintaining biodiversity. Anuran amphibians provide many examples of morphologically similar, genetically divergent lineages, posing questions about the relative roles of phylogeny and ecological factors in phenotypic evolution. We focused on three circum-Mediterranean anuran genera (Hyla, Alytes and Discoglossus), characterizing morphological and environmental disparity and comparing diversity patterns across biological levels of organization. Using a comparative phylogenetic framework, we tested how shared ancestry and climatic factors come together to shape phenotypic diversity. We found higher morphological differentiation within Hyla and Alytes than in Discoglossus. Body size and limb morphology contributed most to inter- and intraspecific morphological variation in Hyla and Alytes, but there was no strong phylogenetic signal, indicating that shared ancestry does not predict patterns of phenotypic divergence. In contrast, we uncovered a significant association between morphology and climatic descriptors, supporting the hypothesis that morphological disparity between species results from adaptive evolution.