O papel relativo dos refúgios glaciais e das barreiras geográficas atuais na diversificação de um squamata fossorial na mata atlântica brasileira

Abstract

The tropical region harbors an extraordinary biodiversity, but the evolutionary processes responsible for this pattern remain obscure. Several factors were suggested to play a role in the species diversification in this region. Herein, we test the relative role of the Pleistocene climate oscillations as well as the presence of the São Francisco River on the morphological and genetic structure of Amphisbaena pretrei, an amphisbaenid widely distributed in the Atlantic Forest with a fossorial lifestyle, conserved morphology and low vagility. The goals of this study were (1) to identify climatically stable areas suitable for the occurrence of A. pretrei and (2) to assess whether patterns of morphological and genetic diversity of the species are associated with these areas of environmental suitability or with the São Francisco River. The climatic stability map shows that since 21 thousand years ago there is a large area of environmental suitability for the species that extends from the south of the São Francisco River until the northernmost portion of northeastern Brazil. The morphology data show a distinct group in the southernmost part of the species distribution, suggesting that in this locality morphological diversification has already occurred. Phylogenetic analyses suggest that diversification within this species started at least 1.31 million years ago. Furthermore, there is a strong genetic differentiation related to geographic distance and the presence of the São Francisco River. These results suggest that the process of diversification in A. pretrei began during the Pleistocene, probably due to the climatic oscillations, and continues in the present due to current barriers.