Phylogenomics reveals the evolution, biogeography, and diversification history of voles in the Hengduan Mountains

The Hengduan Mountains (HDM) of China are a biodiversity hotspot whose temperate flora and fauna are among the world's richest. However, the origin and evolution of biodiversity in the HDM remain poorly understood, especially in mammals. Given that the HDM shows the highest richness of vole species in the world, we used whole-exome capture sequencing data from the currently most comprehensive sampling of HDM voles to investigate their evolutionary history and diversification patterns. We reconstructed a robust phylogeny and re-estimated divergence times of the HDM voles. We found that all HDM voles could be divided into a western lineage (Volemys, Proedromys, and Neodon) and an eastern lineage (Caryomys and Eothenomys), and the two lineages originated from two migration events from North Eurasia to the HDM approximately 9 Mya. Both vole lineages underwent a significant acceleration of net diversification from 8-5 Mya, which was temporally congruent with the orogeny of the HDM region. We also identified strong intertribal gene flow among the HDM voles and hypothesized that frequent gene flow might have facilitated the speciation burst of the HDM voles. Our study highlights the importance of both environmental and biotic factors in shaping the biodiversity of mammals in mountain ecosystems.