INVESTIGATION OF GENETIC-DIVERGENCE OF SP AWNING STOCKS IN THE BAIKALSCULPIN COTTOCOMEPHORUS-GREWINGKI (DYBOWSKI) BY MTDNA RESTRICTION ANALYSIS

Mitochondrial DNA polymorphism of 53 individuals of the Baikal sculpin Cottocomephorus grewingki Dubovski from three spawning stocks differi ng in time of reproduction (March, n = 8; May, n = 15; and August, n = 30) was assayed using restriction analysis. Forty two independent sit es, including 16 polymorphic ones, were found for eight specific restr iction enzymes. Four out of 18 detected haplotypes were found in more than half of the sample and were common for at least two populations e xamined. An analysis of the phylogeny of haplotypes showed that the th ree most common ones probably were present in the ancestral population . Divergence between mtDNA of all individuals analyzed was 0.43% of nu cleotide substitutions. Only 27% of the total mtDNA polymorphism was c aused by interpopulation differences. These results indicate a low lev el of genetic subdivision of C. grewingki for the three spawning popul ations.