Phylogeography of Polygala tenuifolia inferred from chloroplast DNA trnL intron sequence variation / 中草药

ABSTRACT

Objective: To study the molecular phylogeography of natural populations of Polygala tenuifolia (Polygalaceae) in China, reveal the forming reasons of geographic distribution pattern of extent populations, and further determine the potential glacial refuges and colonization/migration routines of P. tenuifolia during the postglacial or interglacial periods. Methods: We investigated the distribution patterns of genetic variation of 308 individuals from 39 natural populations of P. tenuifolia in China based on one chloroplast DNA fragment (cpDNA trnL intron). Results: A total of 26 polymorphic sites were identified and 12 cpDNA haplotypes were recovered. Phylogenetic analysis of cpDNA haplotypes suggested that the natural populations of P. tenuifolia could be divided into two different groups northern part (including populations of northeast, center, and northwest of China) and southern part. There were no shared cpDNA haplotypes between the two groups. And the population genetic analysis suggested that the high level of genetic differentiation (Gst = 0.783, P < 0.001) between the two groups, the high level of the genetic diversity were found (Ht = 0.755) at the species level. No significant phylogeographic structure was detected in the North group. Conclusion: The present studies revealed that the multiple glacial refuges of P. tenuifolia are identified in the northern and southern parts of China during the Quaternary periods. And northern populations have occurred the expansion events during the post-glacial or interglacial periods. The genetic divergence between the north and south groups of natural populations of P. tenuifolia may be caused by the long term geographic isolation.