Vicariant events in the montane hummingbird genera Augastes and Schistes in South America

摘要

We assessed the evolutionary histories of two hummingbirds, Augastes scutatus and Augastes lumachella, endemic to the highlands of the Espinhaco Range in Brazil. These hummingbirds are considered relictual taxa with phylogenetic affinities to members of the genus Schistes from the Andean region. We reconstructed phylogenetic relationships of Augastes through the use of mitochondrial DNA and nuclear sequences within the Polytminae hummingbird clade, and found that the inferred phylogenetic reconstructions placed A. scutatus as the sister species of A. lumachella and Augastes as sister to Schistes geoffroyi from the northern Andes, as previously suggested by similarities found in plumage and morphology. Our results are consistent with an initial divergence of Augastes and Schistes lineages in the Late Miocene, associated with geological and climatic changes across the South American landscape. A Late Pliocene vicariant event between A. scutatus and A. lumachella may be associated with climatically distinct environmental conditions influencing the local differentiation and adaptation of ancestral Augastes populations. Our findings represent additional important evidence of vicariant events between east and west in southern South America, and between north and south within the Espinhaco Range of Brazil.