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.     

Interregional differentiation of chum salmon from Sakhalin and South Kurils inferred from microsatellite markers

Variability at ten microsatellite loci was examined in wild and hatchery populations of chum salmon (Oncorhynchus keta Walbaum) from the Sakhalin Island and Southern Kuril Islands, Iturup and Kunashir. Substantial genetic differences between Sakhalin and South Kurils chum salmon (the differentiation reached 6.0%) were revealed. Statistically significant differences between chum salmon from Iturup and those from Kunashir were demonstrated, as well as between the chum salmon populations from different rivers within the islands. It was shown that in different types of population comparisons, different marker sets were most informative.     

Interregional differentiation of chum salmon from Sakhalin and South Kurils infered from microsatellite markers

Variability at ten microsatellite loci was examined in wild and hatchery populations of chum salmon from the Sakhalin Island and Southern Kuril Islands, Iturup and Kunashir. Substantial genetic differences between Sakhalin and South Kurils chum salmon (the differentiation theta reached 6.0%) were revealed. Statistically significant differences between chum salmon from Iturup and that from Kunashir were demonstrated, as well as between the chum salmon populations from different rivers within the islands. It was shown that in different types of population comparisons, required different marker sets most informative were.     

Genetic diversity of Asian chum salmon <Emphasis Type="Italic">Oncorhynchus keta</Emphasis> (Salmonidae,Salmoniformes) and the dynamics of gene pools in Sakhalin populations under artificial reproduction

The estimates of genetic diversity in populations of chum salmon Oncorhynchus keta from different regions of Sakhalin Island, Iturup Island, and the Anadyr’ River were obtained on the basis of analysis of allozyme variability. These estimates together with our published earlier data on chum salmon from the Amur River basin and the rivers of the northern coast of the Sea of Okhotsk demonstrate pronounced regional genetic differentiation in the Asian part of the fish range. The intraregional level of interpopulation genetic diversity was maximum on Sakhalin Island (G _ST = 6.6%) and was small on Iturup Island (G _ST = 0.9%) and the northern coast of the Sea of Okhotsk (G _ST = 0.6%). Interpopulation genetic diversity of Sakhalin chum salmon was almost commensurable to the diversity of the whole pool of studied Asian populations (G _ST = 7.6%) and would be presented more completely in baselines assigned for genetic identification of mixed stocks. It was demonstrated that the character and degree of genetic differentiation between populations of chum salmon from the main hatcheries situated in different regions of the Sakhalin oblast and connected to one another by numerous transplantations of fertilized eggs did not change significantly during an approximately 20-year period of our observation, and this fact suggests low efficiency of such transplantations.     

Phylogeography of mitochondrial DNA in South Asian Dolly Varden char Salvelinus curilus Pallas, 1814 (Salmoniformes, Salmonidae): mediated gene introgression?

In 41 individuals of South Asian Dolly Varden char Salvelinus curilus, nucleotide sequences of tRNA-Pro gene fragment (27 bp) and mtDNA control region (483-484 bp) were analyzed. The fish were collected in 20 localities covering virtually the whole range of the species: Kuril Islands, Sakhalin Island. and Primorye. In addition, six individuals of three other char species (S. albus, S. malma, and S. leucomaenis), which are closely related to S. curilus and inhabit the Russian Far East, were examined. In all, we detected 12 different variants of mtDNA haplotypes that formed three distinct groups differing in 14--20 nucleotide positions. The first group consisted of six haplotypes found in S. curilus in Kuril Islands, Sakhalin, and Primorye (mtDNA phylogroup OKHOTSKIA). The second group comprised four haplotypes representing the mtDNA phylogroup BERING, which had been described earlier (Brunner et al, 2001); they were found in S. curilus in Kuril Islands and Sakhalin, as well as in S. albus and S. malma in Kamchatka and northern Kurils. The third group included two haplotypes detected in S. leucomaenis. The existence of two mtDNA lineages (OKHOTSKIA and BERING) in S. curilus from Kurils and Sakhalin was explained by hybridization and DNA transfer from S. malma to S. curilus. The absence of the BERING haplotypes in S. curilus from Primorye water reservoirs is related to the physical isolation of the Sea of Okhotsk and Sea of Japan basins in past epochs. On the basis of comparing phylogenetic trees, constructed from the data on allozyme and mtDNA variation, we suggest that in this case, an indirect transfer of mtDNA in Alpinoid chars--> S. malma-->S. curilus chain could occur.     

Phylogeography of mitochondrial DNA in South Asian Dolly Varden char <Emphasis Type="Italic">Salvelinus curilus</Emphasis> Pallas, 1814 (Salmoniformes,Salmonidae): Mediated gene introgression?

In 41 individuals of South Asian Dolly Varden char Salvelinus curilus, nucleotide sequences of tRNA-Pro gene fragment (27 bp) and mtDNA control region (483–484 bp) were analyzed. The fish were collected in 20 localities covering virtually the whole range of the species: Kuril Islands, Sakhalin Island, and Primorye. In addition, six individuals of three other char species (S. albus, S. malma, and S. leucomaenis), which are closely related to S. curilus and inhabit the Russian Far East, were examined. In all, we detected 12 different variants of mtDNA haplotypes that formed three distinct groups differing in 14–20 nucleotide positions. The first group consisted of six haplotypes found in S. curilus in Kuril Islands, Sakhalin, and Primorye (mtDNA phylogroup OKHOTSKIA). The second group comprised four haplotypes representing the mtDNA phylogroup BERING, which had been described earlier (Brunner et al, 2001); they were found in S. curilus in Kuril Islands and Sakhalin, as well as in S. albus and S. malma in Kamchatka and northern Kurils. The third group included two haplotypes detected in S. leucomaenis. The existence of two mtDNA lineages (OKHOTSKIA and BERING) in S. curilus from Kurils and Sakhalin was explained by hybridization and mtDNA transfer from S. malma to S. curilus. The absence of the BERING haplotypes in S. curilus from Primorye water reservoirs is related to the physical isolation of the Sea of Okhotsk and Sea of Japan basins in past epochs. On the basis of comparing phylogenetic trees, constructed from the data on allozyme and mtDNA variation, we suggest that in this case, a mediated transfer of mtDNA in Alpinoid chars → S. malma → S. curilus chain could occur.     

Molecular genetic diversity of musk deer Moschus moschiferus L., 1758 (Ruminantia, Artiodactyla) from the northern subspecies group

Genetic diversity within the northern subspecies group of musk deer Moschus moschiferus L., 1758 was examined based on the mtDNA control region hypervariable fragment (300-bp) sequence polymorphism. Nucleotide diversity, constituting 2.6% for the whole sample (n = 34), varied in the range from 0.6 to 1.9% for individual subspecies. Maximum values of this index were observed for Siberian subspecies (M. m. moschiferus), which had the widest range. Genetic similarity between the haplotypes of the musk deer from the Far East (Russia) and Sakhalin Island, which grouped in one cluster in a phylogenetic tree, was demonstrated. The data obtained indicate that the distribution of musk deer along the territory of Russia occurred from Eastern Siberia to the Far East, and from there to the Sakhalin Island. A currently observed decrease of the musk deer population number along with the increased habitat fragmentation can result in a decrease of the total genetic diversity and in inbreeding depression in the local isolated groups.     

The current state of populations of the common tern Sterna hirundo (Linnaeus, 1758) and the Kamchatka tern S. camtschatica (Pallas, 1811) in northern Sakhalin

This paper presents data on the numbers of nesting common and Kamchatka tern populations on the northeastern coast of Sakhalin Island over a more than 20-year period. Distribution maps of the main tern colonies (Chaika, Lyarvo, and Wrangel islands, and an unnamed island situated in Chaivo Bay) are given. Taking into account the current data concerning southern Sakhalin colonies, the total number of terns in Sakhalin Island is about 9000 pairs for the Kamchatka tern and up to 16000 pairs for the common tern. The main biotic and abiotic factors that determine the population dynamics and distribution of nesting terns in northern Sakhalin Island are enumerated.     

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% (G _ST), while over the microsatellite loci it was 0.26% (the ?_ST coefficient, F-statistics based on the allele frequency variance), and 0.90% (the ρ_ST 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 ?_ST values were substantially lower than in terms of ρ_ST 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     

Comparison of genetic diversity in the two arctic–alpine plants Diapensia lapponica var. obovata (Diapensiaceae) and Empetrum nigrum var. japonicum (Empetraceae) between Sakhalin in Russian Far East and Jeju Island in Korea, the southernmost edge of their distribution range

We compared allozyme variation in the two arctic–alpine plants Diapensia lapponica var. obovata and Empetrum nigrum var. japonicum between Sakhalin Island in Russian Far East, within their range core, and the Korean island of Jeju, their world’s southernmost distribution. For D. lapponica var. obovata, Sakhalin populations harbored moderate levels of within-population genetic variation and low among-population divergence, whereas extremely low levels of within-population genetic diversity and high among-population differentiation were found in Jeju Island populations. In contrast, we found moderate levels of within-population variation and low among-population differentiation in E. nigrum var. japonicum in both northern populations (those of Sakhalin and an additional population from northern Japan) and Jeju Island populations. Under a similar scenario of immigration history of arctic–alpine plants on Jeju Island during the glacial periods of the Pleistocene and local persistence through glacial/interglacial cycles, the contrasting genetic structure between D. lapponica var. obovata and E. nigrum var. japonicum is mainly attributable to their different life-history, ecological, and demographic traits: (1) hermaphroditic versus monoecious, dioecious or polygamous, (2) seeds with no adaptations for long-distance dispersal versus berry-like drupes dispersed by animals and birds, and (3) a very small patch near the peak of Mt. Halla with a few hundred individuals versus a relatively continuous distribution around the peak of Mt. Halla with numerous individuals. From a conservation perspective, in situ and ex situ conservation measures should be strengthened for D. lapponica var. obovata on Jeju Island given their extreme rarity there.     

The bryophyte flora of northern Iturup (north-west Pacific): between the circumboreal and East Asian floristic regions

Introduction. The Kuril Islands Chain demarcates the boundary between the circumpolar and East Asian floras in the amphi-Pacific and is a trans-Oceanic migration route from warm-temperate insular East Asia to north-east Asia and Beringia. This paper reviews the flora of the northern part of Iturup Island in regards to its bryogeography and taxonomic diversity, as well as its relative position among other bryophyte floras of north-east and East Asia.

Methods. The paper uses morphological methods to identify the species composition and detrended correspondence analysis to identify the position of the northern Iturup Island in the system of local floras of the eastern, extra-tropical, Pacific.

Key results. The flora is closely related to the bryophyte floras of the southern Kurils and Hokkaido Island, but has been found to be distinctly distant from the ‘true’ cool-temperate East Asian floras, as well as from the boreal and hemiarctic floras of north-east Asia. Instead, the floras of the south Kurils and northern Hokkaido Island belong to a peculiar intermediate phytogeographic province that cannot be unambiguously placed in either the East Asian or circumboreal floristic regions. The hemiboreal character of the bryophyte flora of northern Iturup Island is in contrast to the general appearance of many of the dominant vegetation communities on the island, which are more characteristic of the hemiarctic.

Conclusion. There is no robust evidence to refer the bryophyte flora of northern Iturup either to the circumboreal or East Asian Floristic Region, the flora belongs to a unique intermediate province between the two regions.     

Dynamics of the abundance and conditions of reproduction of mass species of pacific salmons (<Emphasis Type="Italic">Oncorhynchus</Emphasis>) on the northwestern coast of Sakhalin

The efficiency of reproduction of Pacific salmons of the genus Oncorhynchus in the rivers of the northwestern coast of Sakhalin Island is characterized on the basis of long-term data (1989?2014). Differences between the rivers in the northern and southern parts of the region under study have been revealed with respect to the channel type, faunistic composition of the aquatic biota, and prevailing species of salmons. A high spawning efficiency of pink salmon O. gorbuscha, high densities of filling of spawning grounds, and a relatively poor composition of the freshwater ichthyofauna have been recorded in the rivers of the northern part with the mountain–piedmont type of channel. Varied fish population and the high spawning efficiency of chum salmon O. keta have been recorded in the rivers of the southern part with the mainly lowland channel. The salmon spawning area in the rivers of the northern and southern parts has been estimated. The data on the dynamics of the abundance of salmons on the northwestern coast of Sakhalin are given. The total value of the passage of spawners to the rivers of northwestern Sakhalin that is required for effective reproduction has been estimated, ranging from 0.672 to 1.639 million specimens for pink salmon and approximately 0.43 million specimens for chum salmon.     

On morphological diversity of southern Dolly Varden trout Salvelinus malma krascheninnikovi from water bodies of Sakhalin

Morphological and some biological specific features of nine samples of the southern form of Dolly Varden trout Salvelinus malma krascheninnikovi from water bodies of Sakhalin were studied. Comparative analysis was performed of our own estimates and estimates made by other authors of meristic characters of Sakhalin populations of Dolly Varden trout, as well as of samples from water bodies of the Kuril Islands and Western Kamchatka. Sakhalin populations of S. malma krascheninnikovi are characterized by a low level of morphological differentiation and the absence of geographic structure. No clinal latitudinal variation in sample averages was revealed in either of the nine studied meristic characters, including the number of vertebrae for populations of S. malma krascheninnikovi in the range from Bol’shoi Shantar Island to the south of Sakhalin. The cline in vertebral number from Kamchatka, along the Kuril Islands to Hokkaido, is most likely explained by specific features of distribution and introgressive hybridization at the secondary contact of populations of the northern and southern forms of Dolly Varden trout that originated from different glacial refugia and had a different vertebral number rather than by the temperature gradient.     

Genetic differentiation and the problems of conservation of masu salmon (<Emphasis Type="Italic">Oncorhynchus masou</Emphasis> Brevoort, 1856 (Pisces: Salmonidae)) populations

This study focuses on the strategy for the conservation of masu salmon, Oncorhynchus masou, in the northern part of the species range (via the masu populations in Sakhalin Oblast), based on data of its population structure. It is shown that masu populations that inhabit different rivers genetically differ from each other in allele frequencies at microsatellite markers. In the Naiba River basin, at least two genetically distinct masu populations exist: in the upper reaches and in a tributary, the Bolshoy Takoy River. The masu populations on Iturup Island significantly differ from those on Sakhalin Island; within Sakhalin, the masu salmon from the Chernaya River in the southwestern part of the island is genetically distinct from the southeastern Sakhalin and Aniva Bay populations. The genetic diversity of Iturup populations is substantially lower than that on Sakhalin, probably due to their small sizes. The measures for the conservation and recovery of masu salmon populations should be based primarily on their own genetic resources, or, in the case of a lack of spawners, on the base populations of their ecological/geographical region. In the latter case, masu populations of large rivers can be considered as base ones: for southeastern Sakhalin, this is masu salmon of the Naiba River; for Aniva Bay, this is masu salmon of the Lyutoga River. Transplantation of fish, fertilized eggs, or any other genetic material from a population that is different genetically and inhabits the waters with different ecological gradients should be strongly restricted. The formosan masu salmon from Taiwan Island is studied as an example of a strict genetic isolate.     

An Annotated List of Cartilaginous Fishes (Chondrichthyes: Elasmobranchii,Holocephali) of the Coastal Waters of Sakhalin Island and the Adjacent Southern Part of the Sea of Okhotsk

An annotated list of cartilaginous fish (Chondrichthyes: Elasmobranchii, Holocephali) is given for the first time in the 200-year history of studying the ichthyofauna of Sakhalin Island and adjacent waters of the southern part of the Sea of Okhotsk (including the coast of Hokkaido Island) and the northern Sea of Japan. The list includes 43 species in two classes, eight orders, 16 families, and 25 genera. Information on nature conservation status, English and Latin names, depths of habitat, and distribution within the coastal waters of Sakhalin are presented. For a number of species caught off the coast of Sakhalin and in the adjacent waters, information is provided on collection specimens confirming their presence in the region under study. For a number of species of the Rajiformes order (Arctoraja parmifera, A. smirnovi, A. simoterus), the modern ranges and taxonomic status are being refined in the light of new data. The taxonomic status of the so-called “disputed” taxa is discussed as well as the validity of the species considered in the Bathyraja matsubarai complex. Based on the study of the collections, Arctoraja simoterus, previously unknown in the waters of Russia, as well as Myliobatis tobijei, caught in the Bering Sea, has been discovered, which significantly expands the range of this species to the north.     

A new species of the genus Hypsibius (Tardigrada: Parachela: Hypsibiidae) from Sakhalin island, far East Russia

A new species of semiterrestrial eutardigrade, Hypsibius stiliferus, is described from Sakhalin Island, Far East Russia. The new species is distinguished from its congeners by having an irregular, polygonal or subtriangular dorsal sculpture, which increases in size posteriorly, two granular macroplacoids, and a cuticular bar near the base of posterior claw 4, and by lacking a microplacoid and septulum. It is currently known from its type locality and several other localities in northern and southern Sakhalin Island. This is the first report concerning tardigrades from Sakhalin Island.     

Intertidal Communities of Severnyi Bay (Northern Sakhalin Island)

The paper describes the composition, structure and vertical distribution of intertidal communities in Severnyi Bay (the northern extremity of Sakhalin Island).     

The fossil viperfish Chauliodus testa sp. nov. (Stomiiformes: Stomiidae) from the Neogene of western Sakhalin,Russia

The first fossil viperfish from Russia is recorded. It comes from the Neogene of Sakhalin Island and is assigned to a new species, Chauliodus testa (Pisces: Stomiidae). The new species is most similar to living Ch. macouni and differs from it in the completely ossifying cervical centra, the fewer cervical vertebrae, and the short predorsal distance. The finding of deep-sea viperfishes in the Miocene of western Sakhalin is evidence of independent development of the ichthyofauna in the Neogene of the Tartar Strait and Sea of Japan.     

A panel of microsatellite loci for population studies of Sakhalin taimen Parahucho perryi (Brevoort)

Using DNA samples of Sakhalin taimen and a set of microsatellite loci, earlier reported for other salmonid fishes (Salmonidae), successful cross-species amplification was performed. A total of 56 Sakhalin taimen (Parahucho perryi) samples from the Daga, Nabil, Poronai, and Agnevo rivers (Sakhalin Island) were examined at 36 microsatellite loci, most of which were described for other species and first tested in taimen. Among the 21 loci first tested in taimen, two loci produced no amplification products. The remaining 19 loci were successfully amplified (for some loci, new primers were generated). Thirteen of these loci were monomorphic, while six loci were polymorphic and used in further population genetic analysis. In addition, with the purpose of modification of the allele sizes and optimization of the research technique, new primers for the already known 12 loci of Sakhalin taimen were designed. Three more loci were included in analysis without changes. As a result, a joint panel consisting of 21 polymorphic microsatellite markers was suggested for analysis of Sakhalin taimen. This panel was tested with four population samples from the rivers of Sakhalin Island.The results showed that this panel of markers could be used in detailed population studies for evaluation of the level of genetic differentiation, inbreeding, and migrations in Sakhalin taimen, an endangered species with a fragmented range. Using this approach in further studies will make it possible to isolate basic populations, which is necessary for conservation of this rare species.