title: Refugial isolation and range expansions drive the genetic structure of Oxyria sinensis (Polygonaceae) in the Himalaya-Hengduan Mountains.
abstract: The formation of the Mekong-Salween Divide and climatic oscillations in Pleistocene were the main drivers for the contemporary diversity and genetic structure of plants in the Himalaya-Hengduan Mountains (HHM). To identify the relative roles of the two historical events in shaping population history of plants in HHM, we investigated the phylogeographic pattern of Oxyria sinensis, a perennial plant endemic to the HHM. Sixteen chloroplast haplotypes were identified and were clustered into three phylogenetic clades. The age of the major clades was estimated to be in the Pleistocene, falling into several Pleistocene glacial stages and postdating the formation of the Mekong-Salween Divide. Range expansions occurred at least twice in the early and middle Pleistocene, but the spatial genetic distribution rarely changed since the Last Glacial Maximum. Our results suggest that temporary mountain glaciers may act as barriers in promoting the lineage divergence in O. sinensis and that subsequential range expansions and secondary contacts might reshape the genetic distribution in geography and blur the boundary of population differentiation created in the earlier glacial stages. This study demonstrates that Pleistocene climatic change and mountain glaciers, rather than the Mekong-Salween Divide, play the primary role in shaping the spatial genetic structure of O. sinensis.
authors.affiliation: School of Life Sciences, Engineering Research Center of Sustainable Development and Utilization of Biomass Energy Ministry of Education, Yunnan Normal University, Kunming 650092, Yunnan, P. R. China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Meng
authors.affiliation: Graduate School of Oceanography, University of Rhode Island, 02881, RI USA.
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), College of Life Sciences, Northwest University, Xi'an 710069, Shanxi, P. R.China.
authors.forename: Zhonghu
authors.initials: Z
authors.lastname: Li
authors.affiliation: Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, Yunnan, P. R. China.
authors.forename: Yongping
authors.initials: Y
authors.lastname: Yang
authors.affiliation: School of Life Sciences, Engineering Research Center of Sustainable Development and Utilization of Biomass Energy Ministry of Education, Yunnan Normal University, Kunming 650092, Yunnan, P. R. China.
authors.forename: Zhengkun
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Biology, Duke University, Durham, 27708, NC USA.
authors.forename: Liuyang
authors.initials: L
authors.lastname: Wang
mesh_terms: D001499:Bayes Theorem; D002736:Chloroplasts / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000378:metabolism; D019143:Evolution, Molecular; D014644:Genetic Variation; D005828:Genetics, Population; D018745:Genome, Plant; D006239:Haplotypes; D046448:Ice Cover; D009010:Monte Carlo Method; D010802:Phylogeny; D058974:Phylogeography; D019664:Polygonaceae / Q000145:classification / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant