Guest, Heidi J. , Allen, Geraldine A. .
Molecular phylogeography of Rhodiola integrifolia (Crassulaceae): postglacial recolonization of western North America.
The cyclic contraction and expansion of available habitat during the Quaternary period has strongly influenced patterns of genetic variation in plant populations. Genetic diversity is expected to be high in glacial refugia - such as Beringia, and low in recently deglaciated areas. The arctic/alpine plant Rhodiola integrifolia is found at high latitudes from northwestern North America to northeastern Asia and extends southward along mountain ranges on both continents. To explore the genetic diversity of R. integrifolia I surveyed variation in the chloroplast DNA psbA-trnH spacer region of 69 populations from western North America (including Alaska, Yukon, British Columbia, Montana, Wyoming, Colorado and California). Digests with three restriction enzymes (ApoI, BstXI and MseI) revealed 12 haplotypes over the geographic region surveyed. Sequencing of the same cpDNA region in a subset of samples yielded 28 haplotypes. Of the sequence haplotypes, nine were found exclusively within the Beringian refugium, and five exclusively south of the glacial maximum. Three haplotypes were found both within Beringia and in adjacent glaciated British Columbia, Alaska and the Yukon, and five were wholly within glaciated southeast Alaska. Four haplotypes were widespread with disjunct distributions, occurring both in northern populations (within or bordering Beringia), and populations south of the glacial maximum. Two haplotypes were found within glaciated regions and may have persisted in coastal refugia. Populations of R. integrifolia in western North America appear to have persisted both north and south of the Cordilleran Ice Sheet during the most recent (Wisconsinan) glacial advance, and have subsequently recolonized glaciated western Canada primarily from the north since the last glacial maximum.
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1 - University of Victoria, Department of Biology, P.O. Box 3020 STN CSC, Victoria, British Columbia, V8W 3N5, Canada
Presentation Type: Poster:Posters for Topics
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM