PARENT SESSION
Oral Session #15: Paleoecology and Climate Change.
Presiding: J. Betancourt
Monday, August 5. 1:00 PM to 3:45 PM. Graham Meeting Room, TCC.
A molecular-genetic approach to understanding the migration history of Picea (spruce) in North America.
Anderson, Lynn*,1, Hu, Feng Sheng1, Paige, Ken1, 1 University of Illinois, Champaign/Urbana
ABSTRACT- The late-Quaternary migration history of spruce, a taxon that now dominates the modern boreal forests, is a long-standing controversy in our understanding of biome development in North America. Two alternative hypotheses have been proposed to explain the postglacial expansion of spruce following the end of the last glaciation. The first suggests spruce expansion to be part of the rapid postglacial migration from refuge populations confined to southeastern North America. The second hypothesis involves the existence of refugia in unglaciated areas of Beringia and Canada during the last glacial maximum, which expanded in size and geographic extent during the Holocene. A promising new approach to testing these hypotheses is through the use of molecular genetic analysis of modern plant tissues. We are currently analyzing spruce needles from an E-W transect across the modern boreal biome using a suite of non-coding genetic markers from the chloroplast (paternally inherited through pollen), mitochondrial (maternally inherited through seed), and nuclear genomes. Within white spruce (Picea glauca), preliminary sequence results of non-coding introns located in the TrnT and TrnL regions of the chloroplast show four different haplotypes, which are equally distributed throughout spruce's geographic range. The widespread distribution of these haplotypes do not differentiate between migration from genetically variable southeastern refugia, and geographically distinct multiple refugia with extensive pollen exchange. If patterns are due to variable southeastern refugia that migrated northward, further analysis using mitochondrial markers should show a similar pattern to that generated using chloroplast markers. However, if spruce expanded from multiple Beringian and Canadian refugia, mitochondrial analysis should reveal discrete distributional patterns of haplotypes.
KEY WORDS: Picea, spruce, postglacial migration, phylogeography