Tsai, Yi-Hsin Erica , Manos, Paul S. .
Do hosts and their obligate parasites co-migrate? Inferences from post-glacial phylogeographies of beech (Fagus grandifolia) and beech-drop (Epifagus virginiana).
DESCRIBING how the migration patterns of parasites are constrained by their hosts is a first step in understanding the cohesiveness of communities during migration. This study compares the post-glacial migration of the parasitic plant, Epifagus virginiana (beechdrop; Orobanchaceae), with the migration history of its host tree, Fagus grandifolia (American beech; Fagaceae). The host's post-glacial history is well known with past molecular work describing its range expansion and paleo-pollen data reflecting population density changes over time. This history is used to frame questions regarding the migration of the obligate, host-specific parasite, E. virginiana; for instance, was E. virginiana present at the migration front of F. grandifolia with its range expansion mimicking its host's, or was the parasite's spread limited by host density with its migration matching the host's population density changes? To discern among these scenarios we present the molecular phylogeography of E. virginiana based on chloroplast DNA sequences. We identify the parasite's glacial refugia, migration corridors, and overall population structure and compare these with the hostís history. The results show that the range expansion of E. virginiana is largely coincident with the density changes of its host, though in some instances E. virginiana was present in the low density host populations at the migration front. The dependence of parasite establishment on host density results in a lag time between expansion into an area by the host and colonization by the parasite. How the host's distribution and density dictates the parasite's movements has implications for the migration capacity of E. virginiana and how quickly it can respond to climate change. Also, this study provides significant data on herbaceous plant migration that is currently missing and can answer broader questions about the cohesiveness of communities during migration.
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1 - Duke University, Department of Biology, 139 Biological Sciences Building, PO Box 90338, Durham, North Carolina, 27708, USA
Presentation Type: Oral Paper:Papers for Topics
Location: 134/Performing Arts Center
Date: Wednesday, August 2nd, 2006
Time: 11:00 AM