Diversification and biogeographic links between the Andean and Atlantic Forests: niche models and phylogeography of two Passerines

The Andean central forests are separated from the Atlantic Forest by the Chaco and the Cerrado. Despite this isolation, both rainforests share closely related lineages, which suggest a past connection between them. However, little is known about the timing and the distribution of these forest connections. In this study, we used two passerines (Arremon flavirostris and Trichothraupis melanops) as models to evaluate whether the Andean and the Atlantic forests act as a refugia system, as well as to test the history of the biogeographic connection between them. Also, we evaluated the molecular systematic of intraspecific lineages of studied species. We performed phylogeographic analyses based on mitochondrial and nuclear genes, and used Approximate Bayesian Computation (ABC), as well as performed niche similarity analyses and modelled the current and past distribution. The major phylogeographic disjunction within the two species occurred during the Mid-Pleistocene and between the Andes and the Atlantic regions. The phylogeographic and ABC analyses supported that the Cerrado was the main route of connection between these regions, but without giving evidence against a Chaco connection. Paleodistribution models indicated connections between these rainforests in different periods and through the Chaco and Cerrado. Our study suggests that the biodiversity of the Andean and of the Atlantic forests could have been impacted by cycles of connections through the Cerrado and Chaco. These recurrent connections between regions could have been important for the diversification of forest taxa by promoting events of dispersion and colonization between regions. We proposed to split A. flavirostris into two full species.