Broad geographic dispersal is not a diversification driver for Emberizoidea

Abstract

The movement of species to new geographical areas has been proposed to be crucial for speciation. As such, dispersal has been regarded as a likely explanation for the variation in species richness among clades. The Emberizoidea are a highly diverse Oscine bird clade native to the New World that has been characterized for their ubiquitous distribution both ecologically and geographically, making this group ideal to test how biogeographical dispersal could promote speciation. To do so, we relate dispersal rates with speciation rates of Emberizoidea families using a combination of bioregionalization analysis, ancestral area reconstruction and speciation rate estimation methods. We found that the Emberizoidea superfamily likely arose from a widespread ancestor distributed over the New World, with its range evolution being primarily driven by range contraction and the main cladogenetic events for the clade occurring within bioregions. Moreover, we demonstrate that dispersal rates between bioregions showed no relationship with speciation rates, suggesting that the movement to new geographical spaces is not a driver of speciation in this group. Instead, cladogenetic events within individual bioregions promoted by range stability prove to be an important driver for speciation at broad spatial scales for Emberizoidea families.