RAPD MARKERS OF MITOCHONDRIAL ORIGIN EXHIBIT LOWER POPULATION DIVERSITY AND HIGHER DIFFERENTIATION THAN RAPDS OF NUCLEAR-ORIGIN IN DOUGLAS-FIR

We developed a method of screening RAPD markers for the presence of or ganelle DNA products using enriched organelle DNA probes, then used th ese markers to compare the structure of nuclear and mitochondrial RAPD diversity in Douglas fir. Of 237 screened RAPD fragments from 25 prim ers, 16% were identified as originating in the mitochondrial genome an d 3% in the chloroplast genome. The mitochondrial DNA probe correctly distinguished fragments with known maternal inheritance (which is excl usive for the mitochondrial genome in the Pinaceae), and neither of th e organelle probes hybridized to biparentally inherited fragments. Mit ochondrial RAPD markers exhibited low diversity within populations com pared to nuclear RAPD diversity (H-S = 0.03 and 0.22, respectively), b ut were much more highly differentiated than were fragments of nuclear origin at both the population (G(ST) = 0.18 and 0.05, respectively) a nd racial levels (G(ST) = 0.72 and 0.25, respectively). Both nuclear a nd mitochondrial DNA based phylogenetic analyses identified the variet ies as monophyletic groups; the nuclear RAPD markers further separated the north and south interior races.