Potter, Kevin M. , Josserand, Sedley , Frampton, John , Nelson, C. Dana .
Phylogeography of the Eastern North American firs (Abies): A microsatellite study.
UNDERSTANDING the recent evolutionary history of the true fir (Abies) taxa of eastern North America is complicated by the close genetic relationship of these conifers. Differentiated mostly by cone morphology, balsam fir (A. balsamea) is widely distributed across eastern Canada and the Northeastern and Great Lakes states, while Fraser fir (A. fraseri) is limited to a handful of high-elevation populations in the Southern Appalachians. Bracted balsam fir (A. balsamea var. phanerolepis) is intermediate between these taxa in the degree of cone bract exsertion. It occurs in small populations in West Virginia and Virginia, and sporadically throughout the main balsam fir population. Using 10 microsatellite markers designed for Fraser fir, we found a small amount of genetic differentiation among the three taxa (average FST per locus ≈ 0.041). This, and our finding that bracted balsam fir is closely related to both Fraser and balsam fir, support a previously supported classification which treated these taxa as varieties of the same species. Using the Bayesian clustering program STRUCTURE, we found that A. balsamea appears to be divided into three demes: one in the Great Lakes and western region, one in the Northeastern and New England states, and one in the Maritime provinces of Canada. The Northeastern deme was the most genetically diverse, suggesting the possibility of one large central fir refugium during the Pleistocene, with smaller refugia to the east and west. Fraser fir and bracted balsam fir were both most closely related to the Maritime deme of balsam fir. Unexpectedly, a group of bracted balsam firs from New Brunswick and Nova Scotia was not closely related to the bracted firs of West Virginia and Virginia. Our results also indicate the probable introgression of subalpine fir (A. lasiocarpa) genes into the western part of the balsam fir range.
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1 - North Carolina State University, Department of Forestry and Environmental Resources, Campus Box 8002, Raleigh, North Carolina, 27965-8002, USA
2 - U.S. Forest Service, Southern Institute of Forest Genetics, Harrison Experimental Forest, 23332 Highway 67, Saucier, Mississippi, 39574, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, August 1st, 2006
Time: 9:45 AM