Preliminary comparative phylogeographic analyses of Circum-Amazonian Passerine birds

In the Neotropics, some species are distributed across the forested lowlands south and east of Amazonia, the Andean foothills, the Venezuelan Coastal Range, and the Tepuis, conforming a distributional pattern known as the ‘circum-Amazonian distribution’ (CiAm). To date, there is no clear understanding of the processes giving rise to this distribution. Comprehensive studies aiming at unraveling the mechanisms behind the CiAm in a comparative framework have not been conducted yet. Here, we 1) describe demographic parameters of populations belonging to seven groups of passerine birds that exhibit ‘CiAm’ and 2) identify common phylogeographic areas and demographic patterns among them. Preliminary results based on a single mitochondrial locus (ND2) suggest that L. nematura, T. palliatus/tenuepunctatus, and P. rufum exhibit higher levels of populational structure than the rest of the complexes. Dvalues and π (Tajima’s D and nucleotide diversity) from the groups suggest a recent expansion or absence of demographic disturbance. Two main phylogeographic units were identified: a) the central-southern Atlantic Forests and the Uruguayan Savanna (Thamnophilus caerulescens, T. torquatus/ruficapillus, Lochmias nematura, Philydor rufum, and Platyrinchus mystaceus), and b) the northernmost Atlantic Forests and the Caatinga. The Andean foothills do not seem to conform a consistent phylogeographic unit across complexes, maybe due to insufficient sampling or an absence of common evolutionary process. Taxonomically, monophily was recovered for almost all taxa. Species limits within the T. palliates/tenuepunctatus and T. torquatus/ruficapillus complexes need to be revised. Genomic data will provide further insights into the mechanisms underlaying CiAm.