Final remarks
Our analyses of the evolutionary history of T. ruficapillus shows that this species originated in the Late Pleistocene, within the last 1.7. million years, and diversified into three clearly differentiated lineages: an Atlantic Forest lineage and two different lineages in the Andes, with a split in western Bolivia. This pattern of genetic variation highlights the relevance of the open vegetation corridor and the Andes Mountains as diversification drivers for this species, likely in combination with the effect of the Pleistocene climatic cycles. Levels of phenotypic variation, however, are partially discordant with this genetic structuring. Songs are significantly differentiated among subspecies, but their geographic pattern of variation does not coincide with that shown by mitochondrial or nuclear DNA. We found clearly differentiated songs between subspecies that are genetically similar and, on the contrary, lack of detectable song differentiation between the Atlantic Forest subspecies and that of northwestern Bolivia in the Andes, which present a substantial genetic differentiation and belong to different lineages. Similarly, plumage colouration between the Atlantic Forest subspecies and that of the southern Andes did not differ significantly. Future studies should address these discordances with an increased sampling and the analysis of the effect of evolutionary and ecological pressures on song and colour. Finally, our results are in accordance with those of other birds with disjunct populations in the Atlantic and Andean forests for which the open vegetation corridor has promoted diversification (e.g. Lavinia et al. 2015, 2019, Trujillo Arias et al. 2018, 2020, Cabanne et al. 2019). However, these studies show that the level of differentiation between the populations of these forests is notoriously heterogeneous, suggesting an idiosyncratic effect of this barrier and the cycles of connection and isolation of these forests and highlighting the importance of comparative analyses to better understand the role of the main drivers of avian Neotropical diversification and speciation.