GENETIC-DISTANCE AND ENZYME VARIATION IN LOCAL-POPULATIONS OF 2 ECHINODERMS FROM JAPANESE WATERS

Genetic variation and differentiation in two conspecific local populat ions of the two echinoderms, Strongylocentrotus nudus (Echinoidea) and Asterina pectinifera (Asteroidea) from northern Japan were studied by enzyme electrophoresis. A. pectinifera showed much higher genetic var iability than other shallow water echinoderms, and it may be due to th e large population size. The genetic distances between two populations were 0.006 for S. nudus and 0.041 for A. pectinifera, and the allele frequencies at three genetic loci were significantly different between populations. These results suggest that the genetic differentiation h as been accomplished in some degree between two local populations of e ach species. We discussed the relation between the divergence time of two populations estimated from genetic distance and the paleogeographi cal history of the Tsugaru Strait.