K. I. Afanas’ev

Population Structure of Chum Salmon Oncorhynchus keta in the Russian Far East, as Revealed by Microsatellite Markers

Chum salmon populations in the Russian Far East have a complex multi-level genetic structure. A total of 53 samples (2446 fish) were grouped into five major regional clusters: the southern Kurils, eastern Sakhalin, southwestern Sakhalin, the Amur River, and a northern cluster. The northern cluster consists of chum salmon populations from a vast geographical region, including Chukotka, Kamchatka, and the continental coast of the Sea of Okhotsk. However, the degree of its genetic differentiation is low, 1.9%. In contrast, the southern population cluster exhibits much higher variation; for example, differentiation between chum salmon groups within Sakhalin Island reaches 4.6%, and the differentiation between Iturup Island and Sakhalin Island chum salmon is 7.7%. This suggests that southern populations of Asian chum salmon have a more ancient evolutionary history than northern populations. In contrast to the available data, our study indicates a great deviation of southwestern Sakhalin populations from other Sakhalin chum salmon. The Russian Far East chum salmon are genetically diverse and show statistically significant differentiation even within small geographic localities. This can be used to assign samples of unknown origins to definite local populations.

Microsatellite variability and differentiation of hatchery stocks of chum salmon Oncorhynchus keta Walbaum in Sakhalin

Variability at eight microsatellite loci was examined in five populations of chum salmon Oncorhynchus keta Walbaum from Sakhalin hatcheries. The population of Kalinino hatchery had the lowest heterozygosity and the lowest average number of alleles per locus. The populations examined exhibited significant differentiation, θST = 0.026 on average per locus. The maximum genetic differences were found between the populations of the Kalinino and the Ado-Tymovo hatcheries; the latter differs from the remaining populations also by the highest number and high frequencies of specific alleles. The genetic features of the Taranai hatchery population, observed at microsatellite loci, reflect its “mixed” origin.

Genetic differentiation of pink salmon oncorhynchus gorbuscha Walbaum in the Asian part of the range

Genetic variation at 19 enzyme (including 11 polymorphic) and 10 microsatellite loci was examined in the population samples of odd-and even-broodline pink salmon from the southern part of Sakhalin Island, Southern Kuril Islands, and the northern coast of the Sea of Okhotsk. The estimates of relative interpopulation component of genetic variation for the allozyme loci, per broodline, were on average 0.43% (GST), while over the microsatellite loci it was 0.26% (the ϑST coefficient, F-statistics based on the allele frequency variance), and 0.90% (the ρST coefficient, R-statistics based on the allele size variance). The values of interlinear component constituted 2.34, 0.31, and 1.05% of the total variation, respectively. Using the allozyme loci, statistically significant intralinear heterogeneity was demonstrated among the regions, as well as among the populations of southern Sakhalin. Multidimensional scaling based on the allozyme data demonstrated regional clustering of the sample groups, representing certain populations during the spawning run or in different years. Most of the microsatellite loci examined were found to be highly polymorphic (mean heterozygosity > 0.880). The estimates of interlinear, interregional, and interpopulation variation over these loci in terms of ϑST values were substantially lower than in terms of ρST values. Regional genetic differentiation, mostly expressed at the allozyme loci between the populations from the northern Sea of Okhotsk and the Sakhalin and Kuril group of populations, was less expressed at the microsatellite loci. The differentiation between these regions observed can be considered as the evidence in favor of a large-scale isolation by distance characterizing Asian pink salmon. It is suggested that in pink salmon, low genetic differentiation at neutral microsatellite loci can be explained by extremely high heterozygosity of the loci themselves, as well as by the migration gene exchange among the populations (the estimate of the gene migration coefficient inferred from the “private” allele data constituted 2.6 to 3.4%), specifically, by the ancient migration exchange, which occurred during postglacial colonization of the range

Analysis of Microsatellite Loci Variations in Herring (Clupea pallasii marisalbi) from the White Sea

The genetic diversity among spawning groups of herring from different parts of the White Sea was assessed using ten microsatellite loci. All loci were polymorphic with the expected heterozygosity estimates varying in the range of 12.7–94.1% (mean was 59.5%). The degree of genetic differentiation displayed by White Sea herring was statistically significant (θ = 2.03%). The level of pairwise genetic differentiation FST was 0–0.085, and it was statistically significant in most of the comparison pairs between the herring samples. A hierarchical analysis of molecular variance (AMOVA) revealed the statistically significant differentiation of White Sea herring. 96.59% genetic variation was found within the samples and 3.41% variation was found among the populations. The main component of interpopulation diversity (1.85%) falls at the differences between two ecological forms of herring, spring- and summer-spawning. Within the spring-spawning form, the presence of local stocks in Kandalaksha Bay, Onega Bay, and Dvina Bay was demonstrated.

Genetic variations in Clupea pallasii herring from Sea of Okhotsk based on microsatellite markers

The genetic variations among spawning groups of herrings from different spawning grounds of the northwestern part of the Sea of Okhotsk was assessed using ten microsatellite loci. All loci were polymorphic with the expected heterozygosity estimates varying at different loci in the range of 0.7–95.0% (with a mean of 68.5%). The degree of genetic differentiation displayed by the herrings from the Sea of Okhotsk was not statistically significant (θ = 0.74%). The level of pairwise genetic differentiation FST varied in the range of 0.002–0.014, nor was it statistically significant in all comparison pairs between the herring samples.

Comparative Analysis of Genetic Variability of White Sea Cod (Gadus morhua marisalbi) at Allozyme and Microsatellite Markers

Variability of cod spawning and feeding schools from Kandalaksha Bay of the White Sea, was examined at six allozyme and eight microsatellite loci. The degree of genetic differentiation at allozyme loci constituted θ = 0.36% [95% bootstrap interval 0.0458; 0.6743]. The differentiation estimates obtained using microsatellite markers were higher, θ = 1.33% [0.057; 3.11]. It was demonstrated that the level of genetic diversity in the White Sea cod was lower than that established for the Atlantic cod from Barents Sea using the same set of allozyme and microsatellite markers. The genetic data obtained support the opinion that the White Sea cod is a reproductively independent group formed as a result of the Holocene dispersal of Atlantic cod.

Variation in morphometric and genetic characteristics of stellate sturgeon juveniles raised at different densities

Genetic and size/weight characteristics of stellate sturgeon juveniles were examined under standard and twice lower than standard densities. Viability, growth rate, and variability of juveniles were higher at standard density. Individuals with different genotypes exhibited higher viability and faster growth at different densities, which was particularly pronounced in case of the PGM1 locus. Despite the high phenotypic variability of sturgeon juveniles under standard conditions, its genetic component was higher at low density. It was concluded that low density conditions, which are closer to the natural ones, promote maintenance of the optimal level of genetic variability.

Variability of DNA microsatellite loci in populations of Pacific cod Gadus macrocephalus Tilesius (Gadidae)

Despite almost a hundred years of studies on the Pacific cod’s biological and ecological peculiarities, many of them and especially population structure remain poorly understood. The variability of DNA microsatellite loci Gmo3, Gmo34, Gmo35, Pgmo32, and Gmo 19 was analyzed for the cod sampled in different areas of the North Pacific. The cod sampled nearby the Southern Kurils, differed significantly by Gmo3 and Pgmo32 compared to the populations inhabiting the Bering Sea, the Sea of Okhotsk and the coastal waters off Canada. Further, Pacific cod of the three latter populations demonstrated high similarity (I = 0.996) in spite of considerable geographic remoteness of these areas from one another.

Preliminary data on the variability of three microsatellite loci in Pacific Gadus macrocephalus and Atlantic G. morhua cod (Gadidae)

Variability of microsatellite DNA loci Gmo3, Gmo34, and Gmo35 is studied in samples of Pacific cod Gadus macrocephalus and Atlantic cod G. morhua. The results show high values of identity of the samples within the North Pacific basin (0.9766–0.9924) and within the Northeast Atlantic basin (0.9580). Based on the pairwise assessment of genetic differentiation, the FST values are significantly different in all variants between the samples of Pacific and Atlantic cod (FST = 0.5235–0.6719, p < 0.001). Within the basins, the significant differences in the frequencies of main alleles are revealed in the loci Gmo3 and Gmo34 for the samples from the Pacific and Atlantic oceans, respectively.

Population genetic differentiation of white-spotted char Salvelinus leucomaenis (Pallas) in Russian Far East

The population genetic structure of white-spotted char Salvelinus leucomaenis (family Salmonidae) was determined based on variations in ten microsatellite DNA loci in samples from different parts of the species range in the Russian Far East. In a number of samples, variations in 21 allozyme loci were examined, of which five loci were found to be polymorphic. The overall diversity level at the examined markers was comparable to that observed in a closely related char species, Dolly Varden. The estimates of interpopulation genetic differentiation were highly statistically significant in most of the pairwise comparisons among the samples. The overall evaluation of the spatial genetic differentiation in white-spotted char constituted FST = 0.203 and RST = 0.202. Cluster analysis and multidimensional scaling based on microsatellite allele frequencies indicated the possible subdivision of the examined samples into two main groups, i.e., northern (represented by the regions of the north of Khabarovsk krai, Kamchatka, Yama Bay) and southern (with regions including Sakhalin, Primorye, and the Kuril Islands). The allozome data demonstrated a similar pattern of differentiation. The level of intra- and interpopulation genetic diversity in the southern group was higher than in the northern group. The isolation-by-distance test did not identify a significant correlation between genetic and geographic distances among the samples. The data obtained enabled the suggestion that the genetic structure of the populations of white-spotted char was shaped by the influence of historical geological climatic rearrangements of its range and the genetic drift because of relatively low population number and limited in the extent migration activity of its anadromous form.