|SREL Reprint #1833|
Influence of Quaternary history on the population genetic
structure of Douglas-fir (Pseudotsuga menziesii) in the
We used data from 20 enzyme loci to test hypotheses concerning the population
genetic structure of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in the
Great Basin relative to the southern Rocky Mountains of Utah. Detailed
macrofossil data from wood rat (Neotoina) middens indicate that P. menziesii
was absent from the central and northern Great Basin during the last glacial (20
000 - 12 000 years before present), but has recolonized several of the "island"
mountain ranges of that region during the past 10000 years by long-distance
dispersal from populations on the southern Rocky Mountain "mainland". The
genetic consequences of rare, chance dispersal events should be a reduction in
levels of genetic diversity on Great Basin montane islands and more diversity
among island populations relative to the Rocky Mountain mainland. We found
moderate overall reductions in the level of polymorphisin (65 vs. 85%), numbers
of alleles per polymorphic locus (2.69 vs. 2.82), and gene diversity (0. 1 13 vs.
0. 141 ) in Great Basin PP. menziesii relative to P. menziesii from the Rocky
Mountain mainland. Within-population estimates of allozyme diversity, as well as
relative partitioning of that diversity among populations of each region, differed to
a lesser extent between island and mainland regions. Founder effects and genetic
drift thus appear to have had a minor role in shaping the present-day genetic
structure of Great Basin P. menziesii populations.
SREL Reprint #1833
Schnabel, A., J.L. Hamrick, and P.V. Wells. 1993. Influence of Quaternary history on the population genetic structure of Douglas-fir (Pseudotsuga menziesii) in the Great Basin. Canadian Journal of Forest Research 23:1900-1906.