Cenozoic evolution of beta diversity and a Pleistocene emergence for modern mammal faunas in China

Aim Historical changes in community structure underlie modern spatial diversity patterns, but few empirical studies have focused on the variation in the community composition of fossil assemblages at large spatio-temporal scales. We investigated how the spatial differentiation of mammal communities changed in China throughout the Cenozoic in response to tectonic uplift and palaeoclimatic changes and explore the timing of the emergence of the modern spatially structured faunas. Location Time period China. Cenozoic (from 65 Ma to the present). Major taxa studied Methods Terrestrial mammals. We used a compiled database of the distributions of fossils and extant mammals to compare the multiple-site beta diversity among families and genera within six time intervals of the Cenozoic using Sorensen dissimilarity (beta(sor)) and Simpson dissimilarity (beta(sim)). To investigate the timing of the emergence of the modern spatially structured faunas, we applied hierarchical clustering and non-metric multidimensional scaling ordination based on pairwise beta(sim) among seven zoogeographical regions for each time slice. Results Main conclusions The multiple-site beta diversity at the family level displayed hump-shaped changes during the Cenozoic, and it peaked in the Eocene and gradually decreased towards the present. However, the genus-level multiple-site beta diversity remained rather constant throughout the Cenozoic. Pronounced variations in the relationships among the zoogeographical regions were revealed in both the cluster analyses and the ordinations. The modern spatial structure of mammal faunas at the family level was broadly similar to those observed in the Pliocene and Pleistocene. The spatial differentiation of mammal faunas in China dates back to the Eocene and pre-dates the formation of modern topography and climate. Throughout the Cenozoic, the spatial structure of mammal faunas was reorganized by an interplay of the uplift of the Tibetan Plateau, the emergence of the monsoon system and global macroevolutionary processes. The modern relationships among zoogeographical regions at the family level were established in the Pleistocene.