Phylogeography of Angelica nitida ( Apiaceae) , an endemic to the Qinghai-Tibet Plateau

In this study,we examined nuclear ribosomal DNA internal transcribed spacer ( ITS) sequence variation of Angelica nitida,a perennial plant species that is endemic to alpine scree in the Qinghai-Tibetan Plateau. Seven ITS haplotypes were detected among 147 individuals sampled across 16 populations. All populations except one ( population SP) contained haplotype ( H1) . However,analysis of molecular variance ( AMOVA) showed that ITS variation was mainly present among populations ( 67% ) and that significant phylogeographical structure was evident ( N ST G ST ,P0.05) . We inferred from our results that the current distribution pattern of A. nitida resulted from range retreats and expansions during the Quaternary. During Quaternary glaciations A. nitida retreated to refugia at the edge of the Qinghai-Tibet Plateau ,but then expanded its range during interglacials and the current post-glacial period.