Population history of the Blue-backed Manakin (Chiroxiphia pareola) supports Plio-Pleistocene diversification in the Amazon and shows a recent connection with the Atlantic Forest

Abstract

It has been hypothesised that rivers serve as biogeographic barriers and Pleistocene forest refuges may explain the rich species diversity observed within Neotropical rainforests. The lack of correspondence between Amazonian and Atlantic forest species in South America is a good model for testing such hypotheses. We used molecular, ancestral area reconstruction, and potential paleodistribution analyses of Chiroxiphia pareola to test above hypotheses and examine the diversification and/or geographical expansion of populations. Six genes, two mitochondrial and four nuclear, were analysed. All population splits were estimated to have occurred in the Pliocene–Pleistocene period, and the occurrence of an Amazon population split was supported by historical river dynamics. Amazonian populations were not monophyletic, and the eastern Amazonian cluster was a sister of the Atlantic Forest population. Molecular divergence occurring between the Amazonian and Atlantic forest populations was low when compared to splits between the lineages separated by Amazonian rivers. During the early to middle Pleistocene era, regions associated with mountain slopes and riverbanks connected the Amazonian and Atlantic Forest populations near the interior of the Brazilian Northeast semiarid region, which might have facilitated species dispersal from Amazonia into the Atlantic Forest. After this point, the populations were separated, and the Atlantic Forest population remained stable until the end of the Pleistocene and Holocene eras when short-range expansion and demographic growth occurred. Our results provide evidence that highlights the role of rivers and historical climate change in the diversification of Amazonian and Atlantic Forest bird species through the Plio-Pleistocene era.