Genetic structure and allele frequency dynamics in the sockeye salmon population of Lake Dalneye, Kamchatka

Abstract

Data on the inheritance of the protein loci Ldh-B1, Pgm-1 and Est-3 in a sockeye salmon population have been analysed. All of these loci had a strongly Mendelian type of inheritance, with codominant expression of alleles. In progenies from many crossings, a small but statistically significant excess of heterozygotes was observed. Allelic frequencies of the loci Ldh-B1 and Pgm-1 in sockeye salmon of Lake Dalneye were highly constant throughout 15 years. At the same time, small periodic frequency fluctuations were recorded, in accordance with 5-year cycles of the sock-eye salmon population size in this lake. During early growth genetic differentiation of fry was detected. Slowly growing individuals were found to be more homozygous compared to moderately and rapidly growing fishes. A family of DNA repeated sequences (Sau3A) was revealed in genomes of both anadromous and freshwater dwarf forms of sockeye salmon. A DNA fragment belonging to the Sau3A family was cloned in a bacterial plasmid. The number of copies of this fragment is 570 ± 33 in the genome of anadromous fish and 66 ± 12 in the genome of the dwarf form. The number of ribosomal RNA gene copies in genomes of anadromous and dwarf fishes was also calculated (2000 ± 62 and 1690 ± 24, respectively).