Diversity and genetic structure in populations of Pseudotsuga menziesii (Pinaceae) at chloroplast microsatellite loci

Genetic variation was compared between uniparentally-inherited (chloroplast simple sequence repeats, cpSSRs) vs. biparentally-inherited (isozyme and r andom amplified polymorphic DNA, RAPD) genetic markers in Douglas-fir (Pseu dotsuga mensiezii) from British Columbia. Three-hundred twenty-three indivi duals from 11 populations were assayed. In Douglas-fir, the cpSSR primer si tes were well-conserved relative to Pinus thunbergii (11 of 17 loci clearly amplified), but only 3 loci were appreciably polymorphic. At these cpSSR l oci, we found an unexpectedly low level of polymorphism within populations, and no genetic differentiation among populations. By contrast, the nuclear markers showed variation typical of conifers, with significant among-popul ation differentiation. This difference is likely the outcome of both histor ical factors and high pollen dispersal.