Late Neogene dispersal between Atlantic Forest and Cerrado revealed by the biogeography of Aplastodiscus treefrogs (Anura: Hylidae)

Abstract The Atlantic Forest and the Cerrado are South America’s most biodiverse ecoregions, whose historical connectivity has been influenced by climatic and environmental changes. The genus Aplastodiscus , primarily distributed in the Atlantic Forest but with A. lutzorum occurring in the Cerrado, provides an opportunity to investigate historical biogeographical connections between these ecoregions. Here, we present a time-calibrated phylogeny and biogeographic reconstruction of Aplastodiscus to investigate its diversification history and the processes underlying its present-day distribution. We analysed mitochondrial and nuclear DNA sequences from 55 samples and, we reconstructed ancestral areas and geographic distributions using biogeographic models. Divergence estimates indicate that Aplastodiscus diversification occurred from approximately 25.18 to 1.83 Mya, spanning the Miocene and Pliocene. Our biogeographic reconstruction indicates an ancestral distribution in the Atlantic Forest, followed by a range expansion into the Cerrado and a subsequent shift back toward the Atlantic Forest. This pattern suggests that repeated changes in forest connectivity may have facilitated range expansion and contributed to geographic isolation among lineages as connectivity decreased. The occurrence of A. perviridis in southern Brazil and northeastern Argentina further provides a distributional pattern consistent with historical connectivity across the southern Atlantic Forest. Overall, our results suggest that the biogeographic history of Aplastodiscus reflects repeated range shifts associated with Neogene environmental changes, together with geographic isolation and persistence of lineages within heterogeneous landscapes.