Functional Traits Explain Amphibian Distribution in the Brazilian Atlantic Forest

Aim: Species distributions are one of the most important ways to understand how communities interact through macroecological relationships. The functional abilities of a species, such as its plasticity in various environments, can determine its distribution and beta diversity patterns. In this study, we evaluate how functional traits influence the distribution of amphibians, and hypothesize which functional traits explain the current pattern of amphibian species composition in the Atlantic Forest. Location: Atlantic Forest, Brazil. Methods: Using potential distributions of Brazilian Atlantic Forest of amphibian species, we analysed the relative importance of abiotic factors and species functional traits in explaining species richness, endemism (with permutation multivariate analysis), and beta diversity components (i.e. total, turnover and nestedness dissimilarities). Results: Environmental variables explained 59.5% of species richness, whereas functional traits explained 15.8% of species distribution for Anuran and 88.8% for 58 Gymnophiona. Body size had the strongest correlation with the species distribution. Results of nestedness dissimilarities showed that species with medium to large body size, and species that are adapted to living in open areas tended to disperse from west to east direction. Current forest changes directly affected beta diversity patterns (i.e. most species adapted to novel environments increased their ranges). Beta diversity partitioning between humid and dry forests showed decreased nestedness and increased turnover by increasing altitude in the southeastern region of the Atlantic Forest. Main conclusions: Our study shows that functional traits directly influence the ability of the species to disperse. With the alterations of the natural environment, species more apt to these alterations have dispersed or increased their distribution, which consequently changes community structure. As result, there is nested species distribution patterns and homogenization of amphibian species composition throughout the Brazilian Atlantic Forest