Diversification of tanagers, a species rich bird group, from lowlands to montane regions of South America

Synopsis The process of diversification since the late Tertiarywas studied by linking together well-resolved phylogenies andspecies distributions for tanagers (Aves, Thraupini). Speciesrichness patterns reveal very high densities of range-restrictedspecies in the Andes, and to a lesser extent in the Atlanticforests of south-eastern Brazil, and moderate densities of widespreadspecies in the tropical lowlands. Contemporary climate explainswell the variation in species richness for the 25% most widespreadspecies; for the remaining 75% of species with more restricteddistributions, variation can only be explained well from topographyand landscape complexity. Phylogenetically old species are mainlyfound along the Andes and along the Rio coast of Brazil. Mostother areas outside the Andes probably had very moderate ratesof later diversification. In contrast, the humid tropical Andesregion was a centre of intensive speciation throughout the evolutionaryhistory of the group, and species richness patterns here seemlargely to be driven by the rate of speciation, with furtherdiversification from the highlands into adjacent lowlands. Thediversification process in montane areas may be related to highpersistence of lineages in specific areas, something that maybe related to how climatic changes are moderated by local topography.