Meeting Abstract
It is well known that species richness is unevenly distributed across the tree of life. Explanations for this pattern are widely debated, and include clade age, ecological limits, and changes in diversification rates. For most groups of mammals, it remains unclear which of these factors played a major role in shaping differences in species richness among clades. Using Primates as a focal group, we examine the role of clade age and evolutionary rate heterogeneity in the modern distribution of species diversity. We apply phylogenetic comparative methods to a recent phylogeny of Primates to identify discrete shifts in lineage diversification rate. We evaluate age and species richness relationships across Primate clades using Phylogenetic Generalized Least Squares (PGLS), and contrast patterns of species richness variation across the phylogeny with several models of lineage diversification. We find that Primate diversification has accelerated since its origin, with decreased extinction leading to a shift to even higher evolutionary rates in the most species-rich family (Cercopithecidae). Older primate clades tend to be more diverse, however a shift in evolutionary rate is necessary to adequately explain the imbalance in species diversity. Geographic distribution poorly explains divergence between macroevolutionary regimes, and other ecological factors may be more important. Unlike other mammalian orders, the global distribution of primate species diversity appears to have been strongly impacted by heterogeneity in evolutionary rates.
