Genetic divergence among sand-lance Ammodytes personatus populations in Japan

Genotypes at 10 enzyme loci were analyzed by horizontal starch gel electrophoresis for each of 11 populations of sand-lance Ammodytes personatus in Japan. Allele frequencies at each locus were calculated for each population. There were clear differences of allele frequencies at three loci (α-Gpdh, Me-2, Sod) between populations north of Iwate Prefecture and those south of Miyagi Prefecture. A cluster analysis based on genetic similarities calculated from allele fre-quencies at all 10 loci observed suggests that sand-lance among the Pacific coast of Japan are composed of two population groups; northern and southern groups. The boundary exsists be-tween Iwate and Miyagi Prefecture. Geographic distribution of these two groups is consistent with that of two groups previously described by morphological studies. Genetic distance between these groups falls within the values of intraspecific marine teleost populations. Comparison of genetic similarities and mean heterozygosities among populations suggests that the southern group has a smaller-scale genetic divergence and more homogeneous genetic structure than the northern group.