稀貴 樹種 시로미의 遺傳變異

Genetic variation in the endemic rare tree species, Empetrum nigrum var. japonicum K. Koch

Low levels of genetic diversity are common for a number of geographically restricted plants. However, in some species, high levels of variability have been found in rare species. Empetrum nigrum var. japonicum is a rare, narrow endemic on the top of Mt. Halla and Mt. Paikdu. Genetic variation of Empetrum nigrum var. japonicum in Mt. Halla was examined with allozyme markers. Levels of genetic diversity (A/L=2.0, P=81.82, Ho=0.248, He=0.306) measured for 11 loci were notably higher than those of other tree species with similar ecology and life-history characteristics. Possible explanations for the high levels of genetic diversity found in this species are (1) Empetrum nigrum var. japonicum is a monoecism as well as a dioecism, (2) the mode of reproduction of Empetrum nigrum var. japonicum is sexual and asexual, and (3) a lot of scattered individuals around population may function as stepping-stones which increase gene flow among subpopulations and/or individuals and consequently maintain high levels of genetic diversity within populations.