Amat, F

Evolution of morphology in Western Palaearctic salamanders: do climate and reproductive mode drive body size and shape in terrestrial salamanders? pp. 44-52 plus Supplementary documents

Abstract. Fully terrestrial lifestyles have evolved in a lineage of salamanders living since the Oligocene in the Western Palaearctic that adaptively radiated in morphology, ecology and reproductive modes. I analyse the relationships between body size and shape, and climate and reproductive mode in true terrestrial salamanders of the family Salamandridae. Principal component analyses were carried out on bioclimatic and morphologic data and used to reconstruct the diversification of these along the evolutionary timeline of this lineage. Additionally, a phylogenetic generalized least squares regression was performed in order to test the effect of climate and reproductive mode on their morphologic diversification. Western Palearctic salamanders experienced a strong disparity between small and elongated forms early during their evolution, and short-bodied species exhibit large size variation. Body elongation in the Salamandridae seems to be linked to an adaptation to semifossorial habits and is currently restricted to a narrow range of climatic conditions, which is in contrast to the other terrestrial species. Within this latter group, large species exclusively live at the southernmost edge of the geographic range of true terrestrial salamanders. Thus, Bergmann’s rule is not adhered to by true salamanders, since larger species live in hot climates. The ancestral oviparous mode of reproduction in the Salamandridae could be maintained in elongated salamanders due to their body shapes not posing constraints, whereas the largest sized short-bodied species have developed larviparism.

Key words. Morphology, evolution, Salamandridae, ecological diversification, climatic niche.