hylogeographical Patterns of an Alpine Plant, Rhodiola dumulosa (Crassulaceae), Inferred from Chloroplast DNA Sequences

Yan Hou and Anru Lou

State Key Laboratory of Earth Surface Processes and Resource Ecology, College of Life Sciences of Beijing Normal University, Beijing 100875, China.

Abstract: 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 5881 bp (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. First, this species migrated from refugia in the Qinghai-Tibetan Plateau to northern areas via the intervening highlands when temperatures increased; second, the highland populations migrated toward the mountaintops when temperatures increased further because R. dumulosa is adapted to cold environments. During the second migration step, the common ancestral haplotypes may have been gradually lost.

Keywords: cpDNA haplotype; glacial refugia; migration; phylogeography.

Published in Journal of Heredity. 2014, 105(1): 101-110.