Pleistocene climatic changes and topography drove genetic variation in southern Atlantic Forest treefrogs from Boana polytaenia complex species (Anura, Hylidae)

Abstract

Mountainous regions play a crucial role in shaping genetic differentiation among organisms. Climate change and topographical complexity are considered as the most important processes influencing the diversification of these areas. We used two tree frog species, Boana polytaenia and Boana bandeirantes to access how such biogeographical factors shaped their evolutionary history in the highly biodiverse Brazilian mountain range Serra do Espinhaço, that comprises two main mountain chains (Serra do Mar and Serra da Mantiqueira). We investigate whether the patterns of genetic diversity and differentiation were related to Pleistocene climate shifts and/or climate dynamics through elevational gradients in the mountains. We used a multilocus dataset comprising mitochondrial and nuclear DNA sequences from both species. We assessed the genealogical relationships of lineages, population structure, changes in effective population sizes over time, time of divergence of lineages, climatic suitability through time with ecological niche modeling and whether niche of linegaes are more or less similar than expected. Both species exhibited well-structured lineages in each of the mountain chains, B. polytaenia for Serra da Mantiqueira and B. bandeirantes for Serra do Mar. Diversification primarily occurred during the Middle Pleistocene, with glacial periods influencing B. polytaenia and interglacial periods favoring B. bandeirantes. The combination of Pleistocene climate changes and mountain topography influenced spatial distribution, leading to genetic variation among B. polytaenia complex species.