Geographic patterns of taxonomic and phylogenetic β-diversity of angiosperm genera in regional floras across the world.

Beta diversity (β-diversity) is the scalar between local (α) and regional (γ) diversity. Understanding geographic patterns of β-diversity is central to ecology, biogeography, and conservation biology. A full understanding of the origin and maintenance of geographic patterns of β-diversity requires exploring both taxonomic and phylogenetic β-diversity, as well as their respective turnover and nestedness components, and exploring phylogenetic β-diversity at different evolutionary depths. In this study, we explore and map geographic patterns of β-diversity for angiosperm genera in regional floras across the world. We examine both taxonomic and phylogenetic β-diversity and their constituent components, and both tip-weighted and basal-weighted phylogenetic β-diversity, and relate them to latitude. On the one hand, our study found that the global distribution of β-diversity is highly heterogeneous. This is the case for both taxonomic and phylogenetic β-diversity, and for both tip-weighted and basal-weighted phylogenetic β-diversity. On the other hand, our study found that there are highly consistent geographic patterns among different metrics of β-diversity. In most cases, metrics of β-diversity are negatively associated with latitude, particularly in the Northern Hemisphere. Different metrics of taxonomic β-diversity are strongly and positively correlated with their counterparts of phylogenetic β-diversity.