Abstract
Allozyme variation of diploid loach Misgurnus anguillicaudatus was examined in samples collected from 44 localities in Japan. Genetic differentiation was estimated based on allele frequencies of 12 enzyme loci. Nine loci (36.9%) were polymorphic (< 0.95 in major allele frequency) and average heterozygosities were unusually high (Ho=0.110 ± 0.051, He=0.131 ± 0.052). The coefficient of gene differentiation (Gst=0.774) suggested high genetic differentiation among populations. Based on the unweighted pair-group method using arithmetic averages (UPGMA) dendrogram, loach populations were grouped into six clusters. The population of Memanbetsu, Hokkaido (group 1) was remarkably different from others (D=0.286). Populations distributed in Niigata, Nagano, Tochigi, Saitama, Chiba and Shizuoka Prefectures (group 6) were also genetically distinct from other loaches (D=0.192). These results suggest genetic differentiation among groups 1, 6, and other loaches may be inter-subspecies level. Other loaches could be separated to four clusters (groups 2-5) at D=0.100-0.065. Genetic differentiation among them seems to be at local race level.
