Phylogeny and diversification of Chinese Araliaceae based on nuclear and plastid DNA sequence data

Chinese Araliaceae consist of 20 genera and ca. 175 species. To assess the evolutionary relationships of Araliaceae and their biogeographic diversification in China, the phylogeny of Chinese Araliaceae was constructed by sampling 96 accessions representing 20 genera and 50 species of Chinese Araliaceae and 45 closely related taxa using sequences of the nuclear ribosomal internal transcribed spacer (ITS) region and six plastid regions (the ndhF gene, the trnL-trnF region, the rps16intron, the atpB-rbcL intergenic spacer, the rpl16 intron, and the psbA-trnH intergenic spacer). Phylogenetic analyses of the combined plastid and ITS data supported the results of the previously studies that the Chinese members of Araliaceae were scattered within the Asian Palmate group and the Aralia-Panax group withOsmoxylon at the base of core Araliaceae. The generic status of Pentapanax and Tupidanthus is not supported. Our analysis clearly places them in Aralia and AsianSchefflera, respectively. In a broader phylogenetic framework of Araliaceae, based on the fossil-calibrated Bayesian dating, Chinese Araliaceae was inferred to have originated in Asia and underwent a rapid radiation in its evolutionary history. Its diversification is hypothesized to have been driven largely by the orogenies in Asia during the Cenozoic. In China, the distribution pattern of the phylogenetic diversity of Araliaceae corresponds with its taxonomic diversity across the entire region.