Genetic structure of natural populations of sterlet (Acipenser ruthenus L.) in the catchment basins of the Kama and Ob rivers based on polymorphic ISSR markers

Starlet ( Acipenser ruthenus L.) is included in the Red Data Books of the Russian Federation, Perm Krai and Kirov Province. Inter-microsatellite DNA polymorphism analysis of sterlet populations of the Kama and Ob rivers has not been performed until now. This paper reports on genetic diversity and genetic structure of five natural sterlet populations of the Kama, Ob and Vyatka rivers based on polymorphism of ISSR-PCR markers. The study was carried out in 2015-2916. DNA was extracted from fragments of pectoral fins of fishes aged 3 to 4 years. DNA samples from 195 individuals were analyzed with five effective ISSR primers. POPGENE 1.31 and GenAlEx6 software was used for statistical processing. Basic genetic parameters were proportion (P95) of polymorphic loci, expected (He) heterozygosity, number of alleles per locus (Na), effective number of alleles per loci (Ne), and number of rare alleles (R). The Bayesian method of population structure analysis was performed using STRUCTURE 2.3.4 software. Genetic structure of a population was characterized by proportion of heterozygous genotypes (HT) in the entire population, the expected proportion of heterozygous genotypes (HS) in the subpopulation, and the proportion of interpopulation genetic diversity (GST). As a result, a total of 128 ISSR-PCR markers were identified. The number of amplified ISSR-PCR markers ranged from 7 to 23 depending on the ISSR primer. It was found that the portion of polymorphic loci in A. ruthenus populations was high and amounted to 0,938. Genetic diversity was the highest in the Vyatka sterlet population (P95 = 0.876; Не = 0.232; Ne = 1.402; R = 10) and the lowest in the Ob sterlet population (P95 = 0.634; Не = 0.100; Ne = 1.175; R = 3). A total of 23 rare ISSR-PCR markers were identified for all the samples studied, and 10 of these markers were characteristic of the Vyatka river sterlets. This indicates the possibility of successful identification of these sterlets by population-specific markers. Genetic structure analysis showed that the expected proportion of heterozygous genotypes (HT) for the total sample was 0.283, whereas HS index was much lower making 0.173, therefore, GST value was high and amounted to 0.386. The studied populations were highly differentiated. The interpopulation component accounted for 38.6 % of genetic diversity, while intrapopulation component was responsible for 61.4 %. In each of the studied populations, the rare ISSR-PCR markers have been determined that can be used for identification of studied populations of this species. Thus, the efficiency of ISSR analysis for the identification of sterlets at population level has been proved. It has been established that polylocus ISSR-PCR markers can be used both for characterizing gene pools and for molecular genetic identification of populations and breeds, including sterlet populations and replacement broodstocks. Recommendations for genetic conservation of the Kama and Ob sterlet populations have been developed. These data should be used to manage replacement broodstocks in sterlet artificial reproduction for further release of the fry in a population with an identical gene pool.