title: Rethinking refugia: Tree topology, divergence dates, and demographic history trace the distribution of the endangered Plymouth gentian (Sabatia kennedyana) from the Pleistocene glaciation to present day.
abstract: OBJECTIVE
  Molecular population genetics is a powerful tool to infer how species responded to past environmental change. In the northern hemisphere, interest is increasing in how species responded to changes in ice coverage and temperature during the last glaciation maximum (LGM, between 18000-21000 yr ago) with a common assumption that glacial refugia were located at the southern edge of a species range.
  
  
  METHODS
  We reconstructed the glacial and postglacial phylogeography of Sabatia kennedyana, a member of the Atlantic Coastal Plains Flora with a current distribution from Nova Scotia (NS) to South Carolina, using both cpDNA and nuclear markers. We also examined clinal variation in morphological traits, in particular relative investment in asexual vs sexual growth.
  
  
  RESULTS
  We find strong evidence that the species did not reside in southern glacial refugia, but rather in primary glacial refugia off the exposed continental shelf extending from Cape Cod and that this area was responsible for the founding of modern populations across the range from Nova Scotia (NS) to the United States. Additionally, based on the finding of higher cpDNA diversity and older cpDNA lineages in NS, we propose that multiple founder events occurred in NS, while only a single lineage gave rise to current populations in the United States.
  
  
  CONCLUSIONS
  By understanding how S. kennedyana responded to past shifts in climate and by identifying areas of high genetic diversity in the northern range edge, we discuss the potential response of the species to future climate change scenarios.
authors: Department of Biology, The University of Winnipeg, 599 Portage Avenue, Winnipeg, Manitoba, R3B 2G3, Canada Department of Botany, University of British Columbia, 3529-6270 University Blvd., Vancouver, British Columbia, V6T 1Z4, Canada.
authors: Adriana
authors: A
authors: Suarez-Gonzalez
authors: Department of Biology, University of Hawai'i at Mānoa, 2538 McCarthy Mall, Honolulu, Hawaii 96822 USA Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, Nova Scotia, B4P 2R6, Canada.
authors: Jolene T
authors: JT
authors: Sutton
authors: School of Environmental Studies, P. O. Box 3060, STN CSC, University of Victoria, Victoria, British Columbia, V8W 3R4, Canada Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, Nova Scotia, B4P 2R6, Canada.
authors: Andrew J
authors: AJ
authors: Trant
authors: Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, Nova Scotia, B4P 2R6, Canada Department of Chemistry, Acadia University, 6 University Avenue, Wolfville, Nova Scotia, B4P 2R6, Canada.
authors: Elena
authors: E
authors: Zamlynny
authors: Department of Biology, The University of Winnipeg, 599 Portage Avenue, Winnipeg, Manitoba, R3B 2G3, Canada Department of Botany, University of British Columbia, 3529-6270 University Blvd., Vancouver, British Columbia, V6T 1Z4, Canada.
authors: Sara V
authors: SV
authors: Good
mesh_terms: D002170:Canada; D057231:Climate Change; D018742:DNA, Chloroplast / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D014644:Genetic Variation; D029965:Gentianaceae / Q000235:genetics*; D006239:Haplotypes / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D058974:Phylogeography; D063148:Plant Dispersal; D000068236:Refugium; D017422:Sequence Analysis, DNA; D014481:United States
chemical_list: D018742:DNA, Chloroplast
keywords: Atlantic Coastal Plain; Bayesian analyses; Gentianaceae; ISSR; Pleistocene; clinal variation; cpDNA; extended Bayesian skyline plot; flora; northern refugia; sexual vs asexual investment