Morris, Ashley B. , Soltis, Douglas E. , Soltis, Pamela S. .
Evidence for northern refugia? Reconsidering phylogeographic patterns in American beech (Fagus grandifolia; Fagaceae).
Recent phylogeographic studies of eastern North American plants and animals suggest that small populations may have persisted much closer to the Last Glacial Maximum (LGM) than was previously hypothesized by fossil pollen reconstructions. Historically, plant ecologists and paleobotanists have emphasized the importance of coastal and montane temperate refugia, ruling out the possibility of more northern refugial populations. Previously published work on American beech (Fagus grandifolia; Fagaceae) supports these historical assumptions to some extent, but also cites the potential for interior refuges in the Midwest, on the basis of cpDNA haplotype diversity. Our objective was to assess the impact of sampling strategy on phylogeographic inference, a consideration that is rarely addressed in the literature. Our strategy was to sample fewer, systematically spaced, localities, while sampling more individuals within populations. To generate data comparable to the previously published study, we sequenced the following cpDNA regions (total = 1918 bp): atpB-rbcL, trnK intron and spacer, and trnL-F intron and spacer. We recovered nine haplotypes from 110 individuals across 37 localities, relative to 17 haplotypes from 122 individuals from 100 localities in the previously published study. Six of our nine haplotypes were shared with the previous data set, but four of those were found in new localities, with one having important implications for hypothesized refugia. We suggest that our data, when combined with those of the previously published study, do not provide evidence for a Midwestern refuge, but instead support previously hypothesized refugia in the Interior Highlands (i.e., the Ozark and Ouachita Mountains) and surrounding regions. Other refugial sites are supported west of the Apalachicola River, the Southern Appalachian Mountains, and eastern North Carolina.
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Ashley Morris's homepage
1 - University of South Alabama, Department of Biology, Life Sciences Building 124, Mobile, AL, 36688, USA
2 - University of Florida, Department of Botany, 220 Bartram Hall, P.O. Box 118526, Gainesville, Florida, 32611-8526, USA
3 - University of Florida, Florida Museum of Natatural History, Department Of Natatural Science, Gainesville, Florida, 32611-7800, USA
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 28th, 2008
Time: 2:45 PM