Phylogeography of an alpine species Primula secundiflora inferred from the chloroplast DNA sequence variation
1,4Feng-Ying WANG 2Xun GONG 1Chi-Ming HU 3Gang HAO 1(South China Botanical Garden, the Chinese Academy of Sciences, Guangzhou 510650, China) 2(Kunming Institute of Botany, the Chinese Academy of Sciences, Kunming 650204, China) 3(College of Life Sciences, South China Agricultural University, Guangzhou 510642, China) 4(Graduate University of Chinese Academy of Sciences, Beijing 100049, China)
The Hengduan Mountains (HM) and adjacent regions have been suggested as the important refugia of the temperate plants during the glacial stages. However, it remains unknown how the HM endemic species can respond to the climatic oscillations. In this study, we examined the chloroplast trnL-trnF and rps16 sequence variation of Primula secundiflora, a relatively common alpine perennial endemic to this region. Sequence data were obtained from 109 individuals of 11 populations covering the entire distribution range of the species. A total of 15 haplotypes were recovered and only one of them is commonly shared by three populations while the others are respectively fixed in the single population. The total diversity (HT=0.966) is high while the within-population diversity (HS=0.178) is low. Despite the high uniformity of the intraspecific morphology, an analysis of molecular variance (AMOVA) revealed a high level of genetic differentiation (97.65%) among populations. The higher NST (0.982) than GST (0.816) (P0.05) suggested a distinctly phylogeographical pattern. Phylogenetic analyses of haplotypes identified four major clusters of the recovered haplotypes: three clades in the north, and the other one in the south. The isolated distribution of clades suggested multiple refugia of this species during the glacial stages. We failed to detect the interglacial or postglacial range expansion of this species as revealed for the other temperate plants. However, the low intra-population diversity suggested that most of the populations should have experienced the in situ shrink-expansion cycles during the climatic oscillations. This inference was further supported by the nested clade analysis, which indicated that restricted gene flow with isolation by distance and allopatric fragmentation were likely the major processes that shaped the present-day spatial distribution of haplotypes in this species. Such a special phylogeographic pattern may have resulted from a combination of both climatic oscillation and complex topology of HM.
【CateGory Index】： Q943