Wall, Wade , Douglas, Norman , Xiang, Qiu-Yun(Jenny) , Hoffmann, William , Wentworth, Thomas , Hohmann, Matthew .
Do endemic plants migrate? The phylogeography of Pyxidanthera barbulata (Diapensiaceae) as a test of the Pleistocene refugial paradigm.
The general paradigm for the phylogeography of Eastern North America postulates the retreat of many plant and animal species into southern refugia followed by northward range expansion after the last glacial maximum. However, plants of the Gulf and Atlantic Coastal Plain demonstrate complex, recurrent distributional patterns that are difficult to explain under this phylogeographical model. An example is the co-occurrence of eight endemic plant taxa with populations from New York to South Carolina, across a large disjunction in which northern and southern populations are separated by >300 kilometers. Pyxidanthera (Diapensiaceae), a plant genus that exhibits this pattern, consists of two taxa recognized as either species or varieties. We investigated the taxonomy and phylogeography of Pyxidanthera using morphological data, cpDNA sequences, and AFLP markers. Morphological characters thought to be important in distinguishing P. barbulata and P. brevifolia demonstrate substantial overlap with no clear discontinuities. Genetic differentiation is minimal and diversity estimates for northern and southern populations of Pxyidanthera are similar with no decrease in rare alleles in northern populations. In addition, the northern populations harbor several unique cpDNA haplotypes. Pyxidanthera appears to consist of one morphologically variable species that persisted in its present range at least throughout the later Pleistocene, while the disjunction between the northern and southern populations may be of comparatively recent origin. This work demonstrates that the refugial paradigm is not always appropriate and that Gulf and Atlantic Coastal Plain endemic plant species, in particular, may exhibit phylogeographical patterns qualitatively different from those of other Eastern North America plant species.
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1 - North Carolina State University, Department of Plant Biology, Campus Box 7612, Raleigh, NC, 27695, USA
2 - North Carolina State University, Department of Plant Biology, Campus Box 7612, Raleigh, NC, 27695-7612, USA
3 - US Army Corps of Engineers, US Army Engineer Research and Development Center, PO Box 9005, Champaign, IL, 61826, USA
Presentation Type: Oral Paper:Papers for Topics
Location: 552B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 10:00 AM