Meeting Abstract
A positive correlation between diversification and rate of phenotypic evolution is predicted by several evolutionary theories, from the ecological theory of adaptive radiation to the hypothesis of punctuated equilibrium. However, most studies of this effect are limited in sampling or representation of morphology. Here, we investigate the relationship between rate of morphological evolution and diversification in the salamander skull using surface geometric morphometrics. These data were gathered for 148 species belonging to all extant families of salamanders. We conducted analyses of taxonomic diversification and rate of cranial evolution in this dataset. Our results demonstrate an increase of the rate of cranial evolution during the Late Cretaceous and the Paleocene-Eocene thermal maxima. These two warming events correspond to diversification and dispersal events in Caudata, as well as in several other clades, such as angiosperms, arthropods, and birds. The high diversification and rate of morphological evolution observed approximately 50 million years ago also correspond to the sole invasion of tropical regions by plethodontids, as well as to their transcontinental dispersion in the northern hemisphere. Our results demonstrate that rate of salamander cranial shape evolution increases during episodes of global warming, alongside increases in taxonomic diversification and geographic dispersal. Further analysis of fine-scale patterns of climate change, niche availability, and their interactions with life history and ecology will provide important new insights into the causes of these increased rates of evolution, diversification, and dispersal in Caudata during periods of global warming.
