PARENT SESSION
Tuesday, August 8, 5:00-6:30 pm
Poster Session 10 - Genetics, evolution, and paleoecology
Exhibit Hall, Ballroom Level, Cook Convention Center
Integrated studies of post-glacial expansion of yellow birch (Betula alleghaniensis) in eastern North America.
Lesser, Mark*,1, Andersen, Jennifer1, Booth, Robert2, McLachlan, Jason3, Minckley, Thomas1, Poinar, Hendrik4, Reeves, Kelly 1, Jackson, Stephen1, 1 University of Wyoming, Laramie, WY2 Lehigh University, Bethlehem, PA3 University of California, Davis, Davis, CA4 McMaster University, Hamilton, Ont
ABSTRACT- Migration of yellow birch (Betula alleghaniensis) into unglaciated territory following the last glacial maximum is poorly understood. Integration of phylogeographic, paleoecological, paleoclimatological, and paleo-DNA approaches can provide a basis for tracking Holocene migration patterns at both the species and population level, and assessing underlying mechanisms. Haplotype diversity in yellow birch is highest in the western Great Lakes region, near the northwestern limit of yellow birch. Glacial-age populations may have been much closer to the glacial margin than previously assumed. Yellow birch macrofossils are absent from most records until the mid-Holocene, appearing first in the St. Lawrence/Appalachian region and then in the central/western Great Lakes. It may have existed in small, dispersed populations owing to unfavorable early Holocene climate, or in areas where macrofossil records have not been obtained. A 600-km transect of eleven small lakes across the western Great Lakes region is providing a detailed record of late Holocene expansion of yellow birch. These records indicate rapid east-to-west expansion between 4000 and 3000 years ago across Upper Michigan and adjacent Wisconsin. Paleohydrological records from kettle peatlands in the region indicate that this expansion occurred during a persistent wet period. DNA has been successfully extracted, amplified, and sequenced from several yellow birch samaras and catkin bracts from late Holocene sediments of Ackerman Lake in Upper Michigan. These samples match existing haplotypes in the region. Extension of the paleo-DNA studies downcore at Ackerman Lake and to other sites in our macrofossil-sampling may reveal further patterns of expansion below the species level.
Key words: paleoecology, migration, yellow birch