title: Out of the Qinghai-Tibet Plateau: evidence for the origin and dispersal of Eurasian temperate plants from a phylogeographic study of Hippophaë rhamnoides (Elaeagnaceae).
abstract: Numerous temperate plants now distributed across Eurasia are hypothesized to have originated and migrated from the Qinghai-Tibet Plateau (QTP) and adjacent regions. However, this hypothesis has never been tested through a phylogeographic analysis of a widely distributed species. Here, we use Hippophaë rhamnoides as a model to test this hypothesis. We collected 635 individuals from 63 populations of the nine subspecies of H. rhamnoides. We sequenced two maternally inherited chloroplast (cp) DNA fragments and also the bi-paternally inherited nuclear ribosomal ITS. We recovered five major clades in phylogenetic trees constructed from cpDNA and internal transcribed spacer (ITS) sequence variation. Most sampled individuals of six subspecies that are distributed in northern China, central Asia and Asia Minor/Europe, respectively, comprised monophyletic clades (or subclades) nested within those found in the QTP. Two subspecies in the QTP were paraphyletic, while the placement of another subspecies from the Mongolian Plateau differed between the ITS and cpDNA phylogenetic trees. Our phylogeographic analyses supported an 'out-of-QTP' hypothesis for H. rhamnoides followed by allopatric divergence, hybridization and introgression. These findings highlight the complexity of intraspecific evolutions and the importance of the QTP as a center of origin for many temperate plants.
authors.affiliation: Molecular Ecology Group, State Key Laboratory of Grassland Agro-Ecosystem, School of Life Science, Lanzhou University, Lanzhou 730000, Gansu, China.|Department of Genetic Ecology, Institute of Botany, Academy of Sciences of the Czech Republic, Zamek 1, 252 43 Pruhonice, Czech Republic.|Department of Botany, Faculty of Science, Charles University in Prague, Benátská 2, CZ-128 01 Prague, Czech Republic.
authors.forename: Dong-Rui
authors.initials: DR
authors.lastname: Jia
authors.affiliation: School of Biology, University of St Andrews, St Andrews, Mitchell Building, Fife KY16 9TH, UK.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Abbott
authors.affiliation: Molecular Ecology Group, State Key Laboratory of Grassland Agro-Ecosystem, School of Life Science, Lanzhou University, Lanzhou 730000, Gansu, China.
authors.forename: Teng-Liang
authors.initials: TL
authors.lastname: Liu
authors.affiliation: Molecular Ecology Group, State Key Laboratory of Grassland Agro-Ecosystem, School of Life Science, Lanzhou University, Lanzhou 730000, Gansu, China.
authors.forename: Kang-Shan
authors.initials: KS
authors.lastname: Mao
authors.affiliation: Department of Genetic Ecology, Institute of Botany, Academy of Sciences of the Czech Republic, Zamek 1, 252 43 Pruhonice, Czech Republic.
authors.forename: Igor V
authors.initials: IV
authors.lastname: Bartish
authors.affiliation: Molecular Ecology Group, State Key Laboratory of Grassland Agro-Ecosystem, School of Life Science, Lanzhou University, Lanzhou 730000, Gansu, China.
authors.forename: Jian-Quan
authors.initials: JQ
authors.lastname: Liu
mesh_terms: D018742:DNA, Chloroplast; D021901:DNA, Intergenic; D031263:Elaeagnaceae / Q000235:genetics*; D006824:Hybridization, Genetic; D010802:Phylogeny; D058974:Phylogeography; D058614:Seed Dispersal; D018609:Tibet
chemical_list: D018742:DNA, Chloroplast; D021901:DNA, Intergenic