History and evolution of alpine plants endemic to the Qinghai-Tibetan Plateau: Aconitum gymnandrum (Ranunculaceae)

How Quaternary climatic oscillations affected range distributions and intraspecific divergence of alpine plants on the Qinghai-Tibetan Plateau (QTP) remains largely unknown. Here we report a survey of chloroplast (cp) and nuclear ribosomal (ITS) DNA variation aimed at exploring the phylogeographic history of the QTP alpine endemic Aconitum gymnandrum. We sequenced three cpDNA fragments (rpl20-rps12 intergenic spacer, the trnV intron and psbA-trnH spacer) and also the nuclear (ITS) region in 245 individuals from 23 populations sampled throughout the species' range. Two distinct lineages with east and west geographical distributions respectively were identified from a phylogenetic analysis of ITS sequence variation and the divergence were estimated to be around 1.45 Ma. Nine chlorotypes that clustered into two major clades were broadly congruent in geographical distribution with the two ITS lineages, which was also supported by an analysis of molecular variance (AMOVA). Analysis of the s...