Geographical Patterns of Allozyme Variation in Angelica japonica (Umbelliferae) and Farfugium japonicum (Compositae) on the Ryukyu Islands, Japan

抄録

Geographical patterns of the genetic differentiation of Angelica japonica and Farfugium japonicum were analyzed using allozyme analysis. Many rare alleles were found only in the southern Ryukyus populations of A. japonica and F. japonicum. Few rare or area-unique alleles were found in the northern Ryukyus or northward populations of these plant species. Genetic diversity (expected heterozygosity) of these plant species showed loss of genetic diversity in populations of a lower altitude island. The populations in low altitude islands might have been recolonized when the islands resurfaced after submersion. A geographical cline of the genetic diversity, which decreased from the central Ryukyus populations to the northward, was found in this study. These geographical patterns, which were common for these plant species, indicate that the southern Ryukyus populations were isolated from those of other areas for a long period, and the northern Ryukyus and populations northward might have recolonized rapidly from the central Ryukyus after the last glaciation.