Tsai, Yi-Hsin Erica , Manos, Paul S. .
Beechdrops on the move: A parasitic plant's tale of host influences on post-glacial recolonization.
While phylogeographies of tree species reconstruct the range expansions of those species, as individual data points they are insufficient to recount the distributional history of the forest community. Species respond individually to climate change, so how communities assemble can only be understood through examination of multiple species histories from a diversity of forest niches. We present work on an understory, parasitic herb (Epifagus virginiana, beechdrop, Orobanchaceae) that has an obligate and host specific relationship with a common eastern North American forest tree (Fagus grandifolia, American beech, Fagaceae). Two chloroplast DNA regions were sequenced and used to reconstruct the post-glacial migration history of E. virginiana. Through use of landscape genetic techniques, coalescent methods, and assignment tests, we elucidate the migration routes of this parasitic plant. E. virginiana is shown to have migrated from the southern Appalachians into the Northeast and then westward into the Midwest. These data are then used to distinguish between hypotheses of recolonization routes based on host data. The parasite's pattern of expansion parallels the development of beech forests as recorded in the pollen record and differs from reports of the initial range expansion of beech as seen in a molecular phylogeography. Comparisons of the parasite and host's histories show that the herb lagged behind the initial expansion of the tree's range and instead modified its distribution based on changes in host density. The composite migration history of this parasite and its host shows how two diverse components of a forest community colonized the landscape separately -- even as aspects of the host's distribution greatly influenced the path of the parasite -- before reassembling into their present day co-distributed range.
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PhyloGeoViz: A program that puts pies charts on Google Maps and Google Earth
Yi-Hsin Erica Tsai\'s web page
1 - Duke University, Department of Biology, Box 90338, 137 Biological Sciences Building, Durham, NC, 27708, USA
2 - Duke University, Department of Biology, 137 Biological Sciences, Durham, NC, 27708, USA
population genetic structure
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 28th, 2008
Time: 1:30 PM