title: Vicariance, long-distance dispersal, and regional extinction-recolonization dynamics explain the disjunct circumpolar distribution of the arctic-alpine plant Silene acaulis.
abstract: OBJECTIVE
  Many arctic-alpine species have vast geographic ranges, but these may encompass substantial gaps whose origins are poorly understood. Here we address the phylogeographic history of Silene acaulis, a perennial cushion plant with a circumpolar distribution except for a large gap in Siberia.
  
  
  METHODS
  We assessed genetic variation in a range-wide sample of 103 populations using plastid DNA (pDNA) sequences and AFLPs (amplified fragment length polymorphisms). We constructed a haplotype network and performed Bayesian phylogenetic analyses based on plastid sequences. We visualized AFLP patterns using principal coordinate analysis, identified genetic groups using the program structure, and estimated genetic diversity and rarity indices by geographic region.
  
  
  RESULTS
  The history of the main pDNA lineages was estimated to span several glaciations. AFLP data revealed a distinct division between Beringia/North America and Europe/East Greenland. These two regions shared only one of 17 pDNA haplotypes. Populations on opposite sides of the Siberian range gap (Ural Mountains and Chukotka) were genetically distinct and appear to have resulted from postglacial leading-edge colonizations. We inferred two refugia in North America (Beringia and the southern Rocky Mountains) and two in Europe (central-southern Europe and northern Europe/East Greenland). Patterns in the East Atlantic region suggested transoceanic long-distance dispersal events.
  
  
  CONCLUSIONS
  Silene acaulis has a highly dynamic history characterized by vicariance, regional extinction, and recolonization, with persistence in at least four refugia. Long-distance dispersal explains patterns across the Atlantic Ocean, but we found no evidence of dispersal across the Siberian range gap.
authors.affiliation: Natural History Museum, University of Oslo, P.O. Box 1172 Blindern, NO-0318 Oslo, Norway Department of Botany, St. Petersburg State University, St. Petersburg 199034, Russia galina.gusarova@nhm.uio.no.
authors.forename: Galina
authors.initials: G
authors.lastname: Gussarova
authors.affiliation: Department of Biology, University of Victoria, PO Box 1700 STN CSC, Victoria, BC, V8W 2Y2, Canada.
authors.forename: Geraldine A
authors.initials: GA
authors.lastname: Allen
authors.affiliation: Natural History Museum, University of Oslo, P.O. Box 1172 Blindern, NO-0318 Oslo, Norway Laboratory of Biosystematics and Cytology, Komarov Botanical Institute, Russian Academy of Sciences 197376 St. Petersburg, Russia.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Mikhaylova
authors.affiliation: Department of Biology, University of Victoria, PO Box 1700 STN CSC, Victoria, BC, V8W 2Y2, Canada.
authors.forename: Laurie J
authors.initials: LJ
authors.lastname: McCormick
authors.affiliation: Natural History Museum, University of Oslo, P.O. Box 1172 Blindern, NO-0318 Oslo, Norway.
authors.forename: Virginia
authors.initials: V
authors.lastname: Mirré
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: Department of Biology, University of Victoria, PO Box 1700 STN CSC, Victoria, BC, V8W 2Y2, Canada Royal British Columbia Museum, 675 Belleville St., Victoria, BC, V8W 9W2, Canada School of Earth and Ocean Sciences, University of Victoria, PO Box 1700 STN CSC, Victoria, BC V8W 2Y2, Canada.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Hebda
authors.affiliation: Natural History Museum, University of Oslo, P.O. Box 1172 Blindern, NO-0318 Oslo, Norway.
authors.forename: Christian
authors.initials: C
authors.lastname: Brochmann
mesh_terms: D054458:Amplified Fragment Length Polymorphism Analysis; D001110:Arctic Regions; D001499:Bayes Theorem; D018742:DNA, Chloroplast / Q000235:genetics; D053476:Extinction, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D058974:Phylogeography; D063148:Plant Dispersal; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D029751:Silene / Q000235:genetics / Q000502:physiology*
chemical_list: D018742:DNA, Chloroplast
keywords: AFLP; Caryophyllaceae; Silene acaulis; arctic-alpine; disjunct distribution; phylogeography; psbD-trnT(GGU) spacer; refugia; rpL32-trnL(UAG) spacer; trnL(UAA) intron; trnL(UAA)-trnF(GAA) spacer