Diversity and divergence of 10 amphibian species from the Santiago River Basin as a result of vulcanism in the Trans-Mexican Volcanic Belt

Abstract

During the Trans-Mexican Volcanic Belt history, geological events related to its formation have produced barriers for highland species, favoring isolation and population diversification. In this study, we investigated the phylogenetic relationships between amphibian populations from the highlands of the Santiago River Basin in Jalisco and Nayarit, Mexico. We sampled 33 individuals belonging to 10 species, from 10 volcanoes and mountains, and along altitudinal gradients from 1,400 to 2,915 m asl. Additionally, 55 samples from populations outside of the study area were included. We amplified a fragment of the cytb gene and using fossils and secondary calibrations we estimated divergence times between species and their populations, using a Bayesian approach. Divergence estimates suggest that separations between species occurred during the Neogene, probably due to geological episodes in the region, while intraspecific divergences occurred mainly during the Quaternary. Our results reveal new patterns that can help the understanding of evolutionary history in highland species.