Cathaya argyrophylla, an endangered conifer with less than 4,000 individuals, is restricted to four isolated distributional areas in subtropic mountains of China. Enzyme electrophoresis and random amplified polymorphic DNA (RAPD) were used to assess the levels and patterns of genetic diversity of C. argyrophylla. In eight populations representing all the four distributional areas, 12 out of 25 allozyme loci assayed (48%) were polymorphic (P), with 1.8 alleles per locus (A) and an expected heterozygosity (He) of 0.25. Forty-two out of 114 RAPD fragments (37%) were polymorphic. These results indicate that C. argyrophylla possesses an overall low level of genetic variation. Particularly, there exists much lower genetic variation within populations in C. argyrophylla (P=30.4%, A=1.38, He=0.102 for allozymes, and P=20.4% for RAPDs) than in other coniferous species. Among populations, however, genetic differentiation estimated by allozyme loci (Fst=0.441) and RAPDs (34.7%) was much higher than those found in other conifers, suggesting that significant differentiation has occurred among populations. The historical factors, including severe bottleneck and subsequent genetic drift during Quaternary glaciations and habitat deterioration and fragmentation in postglaciation, are mostly likely to account for such a population genetic structure in C. argyrophylla. Reduced gene flow and relatively high rates of inbreeding may have also contributed to a low level of genetic variation within populations and marked genetic differentiation among populations. Based on these findings, two conservation strategies are proposed: (1) habitat protection for conserving the populations dynamically, and (2) employment of the breeding programs, such as controlled crossing between the genetically distinct populations.

Key words: allozyme, Cathaya argyrophylla, conservation, Pinaceae, population genetics, RAPD