Allozyme variability and genetic divergence of Pacific trout (species Parasalmo) from western Kamchatka

Genetic variation in several populations of Parasalmo (Onchorhyncus) mykiss from Kamchatka was examined on the basis of data obtained by the author and results from literature. Three (sSOD-1*, LDH-C*, and EST-1*) out of 44 protein-coding loci were highly polymorphic. Low-frequency alternative alleles occurred at sAAT-1,2*, LDH-A2*, EST-5*, IDDH-1,2*, and sMDH-1,2*. The results of the present work and comparison with evidence on North American species indicated that, in the Kamchatka part of the range, P. mykiss is represented by several populations carrying unique alleles and forming a genetically independent group. Gene exchange between North American and Western Kamchatka populations is mainly determined by straying in the feeding stock of the American coastal form entering the Sea of Okhotsk. The genetic divergence and mean heterozygosities in the Kamchatka populations were low (D magnitude of 0.0002-0.0275; HS magnitude of 0.011-0.0371). The difference between the Western Kamchatka populations from the North American coastal form was so small (D magnitude of 0.0109-0.0241) that these forms clustered together. Genetic divergence of the Kamchatka populations and the inland North American P. mykiss is an order of magnitude higher (D magnitude of 0.1973-0.2367).