Global dynamics of dispersal and diversification among passerine birds

Explaining global variation in geographic and taxonomic diversity gradients represents a central focus of macroecology and macroevolution. Ultimately, these diversity gradients have been generated over deep timescales as a consequence of historical variation in rates of dispersal, diversification, and the capacity of different geographic areas to preserve taxa through time. Here, I assess the relationships among these processes, to elucidate the causes of geographic and taxonomic variation in species richness among the most speciose order of birds: the Passeriformes (c. 6,500 species). To achieve this, I comparatively analyze phylogenetic, distributional and eco-morphological trait data collated at broad taxonomic and spatial scales. The results of my analyses strongly support the prevalence of historical dispersal events across large geographic scales, in addition to spatiotemporal variation in diversification rates. These findings reflect that some lineages and some geographic regions (notably tropical mountain regions and