RAPD analysis of genetic variation within and among four natural populations of Betula maximowicziana

Abstract

Betula maximowicziana is a long-lived pioneer tree species in cool temperate forests that plays an important role in the forest ecosystem and has high economic value. Random amplified polymorphic DNA (RAPD) markers were used to evaluate the genetic variation of four natural populations of B. maximowicziana (three in central Honshu and the other in Hokkaido) to obtain fundamental information on this natural resource. Sixty-one reproductive amplified bands were obtained with 23 primers. Of these 61 bands, 22 were monomorphic and 39 were polymorphic. The level of genetic variation within each population may be very similar, because the population rankings according to number of polymorphic loci, Shannon's indices and intra-population genetic variance revealed no definite patterns. Global analysis of AMOVA (analysis of molecular variance) showed that genetic variation among populations accounted for 15.6% of the total variation, with the remainder (84.4%) occurring within population. These results demonstrate that genetic differentiation among the four populations is moderate. Hierarchical AMOVA analysis showed that variation among regions (Hokkaido and central Honshu) accounted for 10.4% of the total genetic variation, suggesting that regional genetic differentiation is relatively high. Significant correlations between pairwise ΦPT values and geographic distance were detected, and results of both a neighbor-joining dendrogram based on pairwise ΦPT values, and principal coordinate analysis (PCO) based on a Euclidean metric revealed that the Furano population in Hokkaido was genetically different from the three populations in central Honshu. The data obtained in this study should have important implications for the conservation and management of regional genetic variation of B. maximowicziana.