PARENT SESSION
Tuesday, August 8, 5:00-6:30 pm
Poster Session 10 - Genetics, evolution, and paleoecology
Exhibit Hall, Ballroom Level, Cook Convention Center
Postglacial migration and phylogeography of Douglas-fir.
Gugger, Paul*,1, 1 University of Minnesota, Twin Cities, St. Paul, MN
ABSTRACT- Human-induced global warming is threatening temperate plant communities, and to survive, plants must either shift their ranges or adapt to the changing conditions. To predict such responses there has been interest in detailed reconstructions of the response of plants to late Pleistocene/early Holocene climate warming. Phylogeography has been used to identify glacial refugia, postglacial migration routes, migration rates, and zones of recent secondary contact among previously isolated lineages. We propose and test two contrasting hypotheses of postglacial migration patterns of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco], a commercially and ecologically important western tree, using phylogeographic techniques: northward migration from southern refugia vs. local elevational expansion from multiple lowland refugia. We sampled 98 Douglas-fir populations in the western United States, and sequenced 3 mitochondrial DNA loci for a subset. Preliminary data from 8 locations yielded 4 haplotypes that suggest Douglas-fir was isolated in at least three refugia during the late Pleistocene; some refugial lineages suggest rapid northward migration while at least one suggests mostly elevational migration. This implies the Douglas-fir may be capable of rapid northward migration in response to future warming, however, if certain lineages continue an elevational trajectory, they may go extinct as they are pinched off mountain tops. Additional sequencing within and among populations will allow for more rigorous analyses of its migration history. Comparing modern spatial variation in drought tolerance to the intraspecific phylogeny will further elucidate the relative timing and spatial extent of recent adaptive evolution, critical information for a better understanding of the future range-shifts.
Key words: phylogeography, Douglas-fir, postglacial migration