Geographic patterns and climate correlates of the deviation between phylogenetic and taxonomic diversity for angiosperms in China

Abstract

Taxonomic diversity (TD) of areas within a region is often strongly and positively correlated with phylogenetic diversity (PD) of the areas. However, variation in speciation and extinction rates and the biogeographic histories of lineages can result in significant deviation of PD from TD (i.e., relative PD after correcting for TD; hereafter PDdev). Identifying areas with higher or lower PDdev within a region is important not only to understanding evolutionary processes associated with the causes of biodiversity patterns across the region but also to identifying areas to be protected for different dimensions of biodiversity. Here, we contrast geographic distributions of PD versus TD for angiosperms in China, explore geographic patterns of PDdev, identify areas where PD is much higher (hotspots) or much lower (coldspots) than expected based on TD, and relate the three diversity metrics to climate variables. We found that geographic patterns of TD were highly congruent with those of PD but they were incongruent with those of PDdev. Areas of unusually high PDdev were generally not those of high TD and PD. Biodiversity hotspots identified based on PDdev generally did not overlap with those identified based on TD and PD. We suggest that identifying areas to be protected should consider not only areas of high TD and PD but also areas of unusually high PDdev, because areas of high PDdev likely hold ancient evolutionary histories and uniqueness, and these areas may not overlap with those having high TD and PD.