Recent past connections between Amazonian and Atlantic forests by comparative phylogeography and paleodistribution models for didelphid mammals

Abstract

Despite the current disjoint distribution of Amazonian and Atlantic forests, evidence suggests past historical connections. Here we investigated the historical connections between three didelphid mammal species from Amazonian and Atlantic forests (Caluromys philander, Marmosa demerarae, and M. murina) using comparative phylogeography and paleodistribution models. We generated ecological niche models from the present until the Pliocene to evaluate changes in distributions over time, focusing on the previously suggested connection routes. We inferred divergence times between populations of each species using the mitochondrial Cytochrome b, estimated the phylogeographic relationships with haplotype networks, and calculated the genetic distances. All species exhibited populations that were separated between the Amazonian and Atlantic forests around 1–2 million years ago, while some populations showed more recent divergences. Paleodistributions were more extensive for periods predating the estimated times of divergence for all species, becoming narrower after this period. We suggest that the climatic oscillations during the onset of the Pleistocene largely influenced the phylogenetic structuring of these forest-dwelling species. This led to the separation of populations currently restricted to Amazonian or Atlantic forests. Our findings also point to repeated connections over time, with both North- and South-Eastern routes compatible with ancient connections. This represents the first simultaneous evaluation of past connections between Amazonian and Atlantic forests combining phylogeographic inferences with paleodistribution models for didelphid marsupials. We suggested the relation of the responses to past climate change, such as increases in the paleodistribution, and species resilience.