Prediction of Origin and Dispersal of the Chinese Genus Bupleurum using RASP Software

Abstract

Molecular phylogenetic analyses of 26 Chinese species of Bupleurum were firstly conducted using nuclear ribosomal DNA internal transcribed spacer( ITS) and cpDNA rps16 based on the RASP( Reconstruct Ancestral State in Phylogenies) software,including the Statistical Dispersal-Vicariance Analysis( S-DIVA) and Binary Bayesian MCMC methods( BBM). Seseli squarrulosum and S. mairei were used as out-groups. Our findings indicate that the proportion of ancestor distributions are most probably from the South China based on ITS and rps16 sequences in special spots,and Southern China is mostly likely the Chinese origin for Bupleurum. The likelihood of dispersal is highest at 20 and 2. 5 megayear before present( Ma Bp),and lowest at 15 Ma Bp in the Time-Event curve. Our study further suggests that the scatter distributions are in North China,and species in northern China were separated from the southern conspecific during the 20 Ma Bp( Lu-shan glacial substage). Species from southern China dispersed outwards via various routes. The genus Bupleurum had a low rate of dispersal at 15 Ma Bp when the southern regions provided refuge for species during the cooling period. Both southern and northern species diversified and dispersed again at 2. 5 Ma Bp( Dali glacial substage) due to the uplift of Qing-Zang Plateau.