XVI International Botanical Congess

We investigated the distribution of allozyme variation in 15 populations of Pinus yunnanensis Franch. Horizontal starch-gel electrophoresis was performed on macrogametophytes collected from 300 plants in 15 populations from Yunnan, china. P. yunnanensis was polymorphic at 1.1% of 33 loci examined and averaged 2.1+0-.20 (mean+standard deviation) alleles per polymorphic locus. Mean population heterozygosity (Ho=0.142+0.019), expected heterozygosity (He=0.147+0.018), and total gene diversity HT =0.1716) were substantially higher than average values reported for other Chinese pines. Over 89% of the total genetic variation was partitioned within populations (GST=0.1090), even though significant levels of variation at individual loci were detected among populations. Genetic identity between populations located in the central Yunnan was high (I=0.983), while populations located in the westnorthern region were more divergent from each other (I=0.974) than from populations found within the eastsouthern region (I=0.983). P. yunnanensis is wind-dispersed pollinia of pines promote high levels of gene flow, resulting in low levels of genetic differentiation between populations. However, the difference of ecological geography and environments between its different distributions gives rise to intraspecific differentiation of P. yunnanensis, e.g. the obvious genetic differentiation occurs between P. yunnanensis var. gymaea (Hsueh) Hsueh and P. yunnanensis var. tenuifolia Cheng et Law.