Pleistocene climatic changes and topography drive genetic variation in southern Atlantic Forest treefrog Boana polytaenia (Anura, Hylidae)

Abstract

Mountainous regions carry important factors that can contribute to the genetic differentiation of organisms. Climate change is among the most important process capable of acting in the diversification of these regions. The mountain complexes Serra da Mantiqueira and Serra do Mar, located in the southern portion of the Atlantic Forest, have characteristics that contribute to high levels of anuran diversity and endemism. Seeking to understand the biogeographic processes that acted in the evolutionary history of these mountain ranges, we used the tree frog species Boana polytaenia to investigate whether the patterns of genetic diversity are related to: (i) Pleistocene climate changes, and/or, (ii) dynamics of climate change through elevational gradients present in the mountain ranges. Thus, through mitochondrial and nuclear DNA sequences of 44 individuals of B. polytaenia, we investigated the genealogical relationships through mitochondrial gene tree, the population structure of lineages, possible changes in the effective population size of the lineages over time, the divergence time between recovered lineages, and finally, through the ecological niche modeling, we verified the influences of past climate on possible changes in the species distribution. We recovered four distinct lineages ordered in two well-structured clades distributed along Serra da Mantiqueira and Serra do Mar Mountain Ranges. The entire process of diversification of the species occurred during the Middle-Pleistocene, and the glacial periods seem to have a greater influence on the distribution of the species. Pleistocene climate changes along with the topographic complexity of the mountain ranges influenced the spatial distribution and drove the genetic variations of B. polytaenia. Differences in the climatic conditions of the Vale do Rio Paraíba do Sul and the regions of higher altitude, where the species occurs, probably prevent gene flow between the lineages. Colder historical periods seem to favor the dispersion of the species, which may provide contact between the lineages of each mountain range.