Geographic Distribution and Genetic Variation of a Vulnerable Conifer Species, Picea koyamae (Pinaceae)

摘要

Picea koyamae is a species which is distributed scarcely and is threatened to extinction, though the details are not well known. We investigated the geographical distribution and genetic variation of this species. Seven habitats ovei the Yatsugatake mountains and Akaishi mountains were confirmed in this study, and it was estimated that in these areas combined there were less than 1,000 living mature trees. Genetic diversity within and among 4 populations was analyzed using allozymes. The mean geneticvariation within populations was in the range of general long-lived tree species. However, genetic variation in the Karamatsu-sawa population at Yatsugatake mountains showed a rather low value. It is conceivable that this population has experienced a bottleneck effect. The genetic differentiation among 4 populations was found to be at an intermediate level between continuously distributing conifers and discontinuously distributing ones. In this study, "P. shirasawae" was suggested to be merely a morphological variation within a population of P. koyamae, and was treated as P. koyamae in our results.