Patterns of gene flow and geographic structure in Pinus concorta Dougl.
1995
Yang, R.C. | Yeh, F.C. (Alberta Univ., Edmonton, Alberta (Canada). Dept. of Renewable Resources)
Allozyme variation in 66 populations from three subspecies of Pinus concorta Dougl. was analyzed: 20 in P. concorta spp. concorta, 35 in P. concorta spp. latifolia and 11 in P. concorta spp. murrayana. The objectives were (i) to assess geographic variation in effective population size (N) and rare alleles (less than 0.05) and (ii) to characterize the extent and patterns of gene flow among populations in each subspecies. There was substantial variation in the estimate of total allele numbers and N among subspecies and among populations within subspecies. The number of private alleles (occurred only in one population) in each population ranged between 0 and 4, averaging 0.6, 0.7 and 1.0 for subspecies latifolia, concorta and murrayana, respectively. The number of rare alleles shared with other populations [a(s)] and per-locus average heterozygosity (h) also varied considerably across populations. Linear correlation estimates of N and a(s) with latitude of populations were significant in subspecies latifolia and murrayana, not in spp. concorta. In contrast, h correlated significantly with latitude only in spp. concorta. The number of migrants exchanged between populations was more than 1 in each subspecies, large enough to obscure the among-population genetic differentiation from theoretical expectation. A significant pattern of "isolation by distance" was evident only in ssp. concorta. Biogeographical analysis suggested the existence of a 'centre of diversity' for spp. latifolia in north-central British Columbia
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