The Qinghai-Tibet Plateau (QTP) encompasses areas with a remarkably high degree of biodiversity, harboring exceptional species-rich radiations. How these radiations formed by interacting with geology, climate and ecology remains seldom examined. We investigate the roles of abiotic (environmental) and biotic (species-intrinsic) factors in driving radiating diversification of Saussurea (Asteraceae) by deploying a number of time-dependent, paleoenvironment-dependent and trait-dependent models, as well as ecological distribution data. We show that three main clades of Saussurea begin to diversify in the Miocene almost simultaneously, with increasing diversification rates toward the present and negative dependence to paleotemperature. Acceleration in diversification rates are correlated with adaptive traits, as well climate lability, niche breadth and species range. We conclude that fluctuation of paleoclimate along with complex QTP environments provided opportunities for increased diversification rates of Saussurea with diverse adaptive traits, highlighting the importance of combinations of clade-specific traits and ecological niches in driving rapid radiation. Key words: radiating diversification, Saussurea, the Qinghai-Tibet Plateau, biodiversity hotspots, adaptive traits, diversification rates, ecological niche.

Background and Aims Abelia (Caprifoliaceae) is a small genus with five species (including one artificial hybrid). The genus has a disjunct distribution across mainland China, Taiwan and the Ryukyu Islands, providing a model system to explore species dispersal mechanisms of the East Asian flora. However, the current phylogenetic relationships within Abelia remain controversial. Methods In this study, we reconstructed the phylogenetic relationships within Abelia using nuclear loci generated by target enrichment and the cpDNA from genome skimming. Key Results: We found large cytonuclear discordance across the genus. Based on the nuclear and chloroplast phylogenies we proposed to merge A. schumannii into A. macrotera, and A. macrotera var. mairei into A. uniflora. Divergence time estimation, ancestral area reconstruction, and ecological niche modelling (ENM) were used to examine the biogeographic history of Abelia. Our results showed that Abelia originated in Southwest China, and diversification began in the Early Eocene, followed by A. chinensis var. ionandra colonizing Taiwan in the Middle Miocene. The ENM results suggested an expansion of climatically suitable areas during the Last Glacial Maximum and range contraction during the Last Interglacial. Disjunction between the Himalaya-Hengduan Mountain region (HHM) and Taiwan is most likely the consequence of topographic isolation and postglacial contraction. Conclusions Overall, our results supports that postglacial range contraction together with topographic heterogeneity resulted in the Taiwan and China mainland disjunction. Furthermore, when we using genome data to reconstruct the phylogeny of related species, branch evolution and network evolution should be considered, as well as gene flow in historical periods. This research provide new insights for the speciation process and taxonomy of Abelia.