title: Arctic plant origins and early formation of circumarctic distributions: a case study of the mountain sorrel, Oxyria digyna.
abstract: Many plant species comprising the present-day Arctic flora are thought to have originated in the high mountains of North America and Eurasia, migrated northwards as global temperatures fell during the late Tertiary period, and thereafter attained a circumarctic distribution. However, supporting evidence for this hypothesis that provides a temporal framework for the origin, spread and initial attainment of a circumarctic distribution by an arctic plant is currently lacking. Here we examined the origin and initial formation of a circumarctic distribution of the arctic mountain sorrel (Oxyria digyna) by conducting a phylogeographic analysis of plastid and nuclear gene DNA variation. We provide evidence for an origin of this species in the Qinghai-Tibet Plateau of southwestern China, followed by migration into Russia c. 11 million yr ago (Ma), eastwards into North America by c. 4 Ma, and westwards into Western Europe by c. 1.96 Ma. Thereafter, the species attained a circumarctic distribution by colonizing Greenland from both sides of the Atlantic Ocean. Following the arrival of the species in North America and Europe, population sizes appear to have increased and then stabilized there over the last 1 million yr. However, in Greenland a marked reduction followed by an expansion in population size is indicated to have occurred during the Pleistocene.
authors.affiliation: Key Laboratory for Bio-resources and Eco-environment, College of Life Science, Sichuan University, Chengdu, 6100065, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Key Laboratory for Bio-resources and Eco-environment, College of Life Science, Sichuan University, Chengdu, 6100065, China.
authors.forename: Jianquan
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Biology, University of Victoria, Victoria, BC, V8W 2Y2, Canada.
authors.forename: Geraldine A
authors.initials: GA
authors.lastname: Allen
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors.forename: Yazhen
authors.initials: Y
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Yue
authors.affiliation: Royal British Columbia Museum, 675 Belleville St, Victoria, BC, V8W 9W2, Canada.
authors.forename: Kendrick L
authors.initials: KL
authors.lastname: Marr
authors.affiliation: School of Biology, University of St Andrews, Mitchell Building, St Andrews, Fife, KY16 9TH, UK.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Abbott
mesh_terms: D001110:Arctic Regions; D001267:Atlantic Ocean; D001483:Base Sequence; D002681:China; D005060:Europe; D014644:Genetic Variation; D006116:Greenland; D008969:Molecular Sequence Data; D009656:North America; D058974:Phylogeography; D018087:Plastids / Q000235:genetics; D019664:Polygonaceae / Q000235:genetics*; D012426:Russia; D017422:Sequence Analysis, DNA; D018609:Tibet
keywords: ancestral location; arctic flora; circumarctic distribution; migration; species origin