Genetic research of anadromous herring in Volga-Caspian fishery basin

Abstract

For the first time, a study of genetic variability of Caspian anadromous herring was carried out using molecular genetic methods. Sequencing of the cytochrome B site of mitochondrial DNA allowed to identify 7 haplotypes. The most massive haplotype was Hap_Alosa1 noted in 29 herring individuals. Five minor haplotypes were detected in few fish individuals. In the marine period of life in fish caught in the Northern Caspian there were noted rare haplotypes Hap_Alosa6 and Hap_Alosa7. In the river period of life in the Volga herring there was observed Hap_Alosa5. The revealed polymorphism of haplotypes was represented by single nucleotide substitutions. The genetic analysis of migratory herring does not give grounds for isolating the studied fish into separate groups. The marked low level of nucleotide diversity of cytochrome B gene of mitochondrial DNA of the anodromous herring indicates a significant genetic homogeneity of the species within the studied range. The results of analysis of nuclear DNA microsatellite loci showed that only three of the six sites of the studied gene were polymorphic. In individuals caught in the river period of life, only Af20 (out of the 6 loci studied) was polymorphic and was characterized by 4 alleles. In a sample of herring from the Northern Caspian, 3 polymorphic loci (Aa16, Af6 and Af20) were observed, in which 2 alleles were recorded. The observed heterozygosity varied from 0.313 to 0.667 exceeding the level of expected heterozygosity. In polymorphic loci a deficit of heterozygotes was not noted. The results obtained in this study indicate a low level of genetic variation of anadromous herring.