Phylogeographical patterns of an alpine plant, Rhodiola dumulosa (Crassulaceae), inferred from chloroplast DNA sequences

The phylogeographical patterns of Rhodiola dumulosa, an alpine plant species restrictedly growing in the crevices of rock piles, were investigated based on 4 fragments of the chloroplast genome. To cover the full distribution of R. dumulosa in China, 19 populations from 3 major disjunct distribution areas (northern, central, and northwestern China) were sampled. A total of 5881bp (after alignment) of chloroplast DNA (cpDNA) from 100 individuals were sequenced. The combined cpDNA data set yielded 36 haplotypes. The total genetic diversity of R. dumulosa was remarkably high (H T = 0.981). The interpopulation genetic differentiation was significantly large (F ST = 0.8537, P < 0.001), possibly due to the long-term isolation of the natural populations. N ST was significantly larger than G ST (P < 0.001), indicating the presence of phylogeographical structure among the R. dumulosa populations. We propose 2 migration steps to explain the current distribution of R. dumulosa in China. Firs...