Phylogeography of the Willisornis poecilinotus / vidua species complex (Aves: Thamnophilidae)

The historical factors that contributed to the high biodiversity in the Amazon region are quite controversial studies have shown that the largest Amazonian rivers represented barriers, promoting isolation and diversification among closely related lineages. However, in the headwaters regions of some Amazonian rivers, there are direct contact zones between avian lineages, which maintain gene flow, even when separated from each other across opposite river banks. Hybrid zones were detected among several pairs of taxa of birds near to the headwaters of the Tapajós River, including two species of the genus Willisornis, showing that the «barrier effect» exerted by the river may be relative. A critical step towards characterizing hybrid zones is the investigation of the phylogenetic relationships among the taxa involved. This study aimed to estimate the phylogenetic relationships within the Willisornis poecilonotus / vidua complex to elucidate the history of the hybrid zone in the Tapajós River and evaluate the existence of additional contact zones in the group. So far, no phylogeographic hypothesis is available for the complex, with previous taxonomic studies based only on vocal and morphological characters. We sequenced 27 samples of all taxa grouped in the complex, except W. p. lepidonotus, for two mitochondrial (ND2 and CytB) and three nuclear (G3PDH, BF5 and MUSK) genes. We estimated a phylogeny using the Bayesian Inference criterion, which recovered 9 reciprocally monophyletic lineages separated by large Amazonian rivers. The results obtained contrast with currently recognized species limits in Willisornis, whereby W. poecilinotus was recovered as paraphyletic with respect to W. vidua.