M. Yu. Kovalev

Collation of data on the ploidy levels and mitochondrial DNA phylogenetic lineages in the silver crucian carp Carassius auratus gibelio from Far Eastern and Central Asian populations

The distribution of the diploid and triploid forms and the correspondence between ploidy and mitochondrial DNA (mtDNA) phylogenetic lineages of the silver crucian carp have been studied in Far Eastern water bodies and the Syr Darya River. Both diploid and triploid forms have been found in large river systems (the Amur, Suifun, Tumangan, and Syr Darya river basins). Only the diploid form has been detected in lakes of Bol’shoi Pelis Island (Peter the Great Bay of the Sea of Japan), Sakhalin Island, and the Kamchatka River basin (the Kamchatka Peninsula). It has been confirmed that there are two mtDNA phylogroups in the silver crucian carp in the area studied. Both mtDNA phylogenetic lineages are present in the Suifun and Tumangan river basins. Only one mtDNA phylogroup (characteristic of the gynogenetic form) has been detected in two samples from the Amur River and in the Syr Darya population. The other mtDNA phylogroup is predominant in insular populations and in Kamchatka. The gynogenetic form carries only mtDNA phylogroup I, whereas both phylogroups have been found in diploid bisexual fish. The existence of only two mtDNA phylogroups substantially differing from each other indicates that the gynogenetic form has emerged from the diploid form only once and evolved independently for a long time after that. The absence of haplotypes transitional between the two mtDNA phylogroups suggests that the secondary contact between the gynogenetic and bisexual forms in continental populations occurred within recent historical time. The obtained data confirm that genetic (though asymmetric) exchange between the two forms is possible, which explains the high morphological and, probably, genetic similarity between them.

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.

Mitochondrial DNA variation in diploid and triploid forms of silver crucian carp Carassius auratus gibelio

Variation of two mtDNA fragments amplified in polymerase chain reaction was compared by the RFLP method in a population of the sympatric bisexual (diploid) and gynogenetic (triploid) forms of silver crucian carp. The mtDNA haplotypes of all individuals was shown to be divided into two phylogenetic groups differing by at least 2.5% of nucleotide substitutions in their sequences. All gynogenetic individuals have haplotypes of a single phylogroup, whereas haplotypes of diploid fish belonged to both mtDNA phylogroups. This testifies to a possibility of transformation of gynogenetic individuals into a bisexual form, whereas the reverse process is either extremely rare or impossible.

Far Eastern Mullet Mugil soiuy Basilewsky (Mugilidae, Mugiliformes): The Genetic Structure of Populations and Its Change under Acclimatization

The introduction of Far Eastern mullet (pilengas) in the Azov Sea in the 1970s–1980s has resulted in the formation of a self-reproducing commercial population. We have carried out a comparative population-genetic analysis of the mullet from the native (Primorye, the Sea of Japan basin) and the new (The Azov Sea basin) ranges. Genetic characteristics of three Primorye and three Azov local samples were studied using electrophoretic analysis of 15 enzymes encoded by 21 gene loci. In the Azov mullet, the initial heterozygosity characteristic of the donor population was preserved while the genotype and the allele compositions changed; the changes included a 1.9-fold reduction in the percentage of polymorphic loci and 1.5-fold reduction in the mean number of alleles per locus. The genetic differences between the Azov and the Primorye sample groups were highly significant. In the native range, no genetic differentiation among the mullet samples from different areas was found (Gst = 0.42%), whereas in the Azov Sea basin, the samples from spatially isolated populations (ecological groups) exhibited genetic differences (Gst = 1.38%). The genetic divergence of the subpopulations and the excess of heterozygotes at some loci in the Azov mullet suggest selection processes that formed genetically divergent groups associated with the areas of different salinity in the new range. The salinity level is assumed to be the most probable factor of local differentiating selection during fast adaptation and naturalization of the introduced mullet.

Mitochondrial DNA Variation in Goldfish Carassius auratus gibelio from Far Eastern Water Reservoirs

MtDNA variation of goldfish samples from several reservoirs of Southern Primorye was examined by RFLP analysis. High mtDNA polymorphism was found in the river populations but not in the lake ones. Considerable among-haplotype divergence was found within samples, which suggests periodic gene exchange between populations having long histories of independent evolution. The absence of substantial differences between clusters of mtDNA haplotypes indicates recurrent transfer from bisexual to gynogenetic reproduction mode and vice versa.

Genetic divergence of populations of the white char Salvelinus Albus , northern and southern forms of malma S. malma (Salmonidae), by microsatellite loci of DNA

A very small but statistically significant genetic differentiation by allele frequencies (in the Kamchatka basin FST = 0.016 and in Kronotskoe Lake FST = 0.063) is revealed between sympatric populations of the northern malma Salvelinus malma malma and of the white char S. albus by analysis of nine microsatellite loci. Factor analysis and clusterization of individual multilocal genotypes in the sum sample of sympatric S. malma malma and S. albus also demonstrate their extremely weak genetic differentiation. Divergence between geographically isolated (allopatric) populations of each of these chars exceeds by two-three times the interspecies differentiation in the zones of sympatry. Samples from allopatric populations clusterize by the geographic principle but not by the taxonomic principle. Such a situation may be explained by the absence of reproductive isolation and presence of hybridization between sympatric S. malma malma and S. albus with the simultaneous existence of some limitations of genetic exchange related to the ecological specialization of these chars. Analysis of microsatellite loci revealed highly significant genetic differences between the northern and southern forms of malma S. malma krascheninnikovi by many times exceeding genetic differences between S. malma malma and S. albus. The obtained data do not confirm the independent species status of S. albus but support the opinion of the species level of differences between the northern and southern forms of malma.

Analysis of the mitochondrial DNA variation in pond smelt Hypomesus olidus (Osmeridae)

Pond smelt Hypomesus olidus (Pallas, 1814), one of the five species of the genus Hypomesus, family Osmeridae, was examined for intraspecific variation of the mitochondrial DNA cytb (1062 bp) and COI (567 bp) genes. Among the ten single substitutions discovered, only one, leading to the substitution of isoleucine by valine, was nonsynonymous, while the remaining substitutions were synonymous. The degree of genetic divergence among pooled nucleotide sequences in H. olidus populations examined constituted 0.4% on average, ranging from 0.2 to 0.6%. These values were not higher than the levels of divergence between the individuals within the populations. Phylogenetic analysis of the populations examined did not reveal their subdivision depending of their geographic location, and pointed to the absence of intraspecific differentiation of the species.

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.

Complete mitochondrial genome of the stone char Salvelinus kuznetzovi (Salmoniformes, Salmonidae)

Abstract The complete mitochondrial genome was sequenced in two individuals of stone char Salvelinus kuznetzovi. The genome sequences are 16,654 bp in size, and the gene arrangement, composition and size are very similar to the salmonid fish genomes published previously. The low level of sequence divergence detected between the genome of S. kuznetzovi and the GenBank complete mitochondrial genomes of the white char S. albus (KT266870 and KT266871), the Northern Dolly Varden char S. malma (KJ746618) and the Arctic char S. alpinus (AF154851) may likely be due to recent divergence and/or historical hybridization and interspecific replacement of mtDNA.

Heavy metal distributions in components of aquatic ecosystems in natural monuments—Lakes Blagodati, Vas’kovskoe (Primorskii Krai) and Azabach’e (Kamchatskii Krai)

Heavy metal concentrations were studied in aquatic organisms (mollusks and higher aquatic plants) and bottom sediments of lakes Blagodati, Vas’kovskoe (Primorskii krai) and Azabach’e (Kamchatskii krai). The geochemical features of watershed rocks, including higher total and leachable concentrations of microelements in bottom sediments (Cu and Ni in Lake Azabach’e, Zn and Pb in Lake Vas’kovskoe) correlate with higher concentrations of those elements in aquatic organisms. Lake Blagodati, where metal concentrations in the sediments are minimal, can be taken as background for Primorskii krai.