Reproduction and development of common species of peanut worms (Sipuncula) from the Sea of Japan

This study deals with the reproduction and development of the most common species of peanut worms from the Sea of Japan: Thysanocardia nigra, Themiste pyroides, and Phascolosoma agassizii. Data on the time of reproduction and larval settlement and the distribution of these species in Peter the Great Bay are provided. The peculiarities of gametogenesis, spawning, and embryonic, larval, and postlarval development are described. The reproductive biology of representatives of these species from the western and eastern Pacific is examined in a comparative aspect.     

Genetic divergence in nuclear genomes between populations of <Emphasis Type="Italic">Fagus crenata</Emphasis> along the Japan Sea and Pacific sides of Japan

Genetic diversity and structure in Fagus crenata were studied by analyzing 14 nuclear microsatellite loci in 23 populations distributed throughout the species’ range. Although population differentiation was very low (F _ST = 0.027; R _ST = 0.041), both neighbor-joining tree and Bayesian clustering analyses provided clear evidence of genetic divergence between populations along the Japan Sea (Japan Sea lineage) and Pacific (Pacific lineage) sides of Japan, indicating that physical barriers to migration and gene flow, notably the mountain ranges separating the populations along the Japan Sea and Pacific sides, have promoted genetic divergence between these populations. The two lineages of the nuclear genome are generally consistent with those of the chloroplast genome detected in a previous study, with several discrepancies between the two genomes. Within-population genetic diversity was generally very high (average H _E = 0.839), but decreased in a clinal fashion from southwest to northeast, largely among populations of the Japan Sea lineage. This geographical gradient may have resulted from the late-glacial and postglacial recolonization to the northeast, which led to a loss of within-population genetic diversity due to cumulative founder effects.     

Comparative Analysis of Japanese Three-Spined Stickleback Clades Reveals the Pacific Ocean Lineage Has Adapted to Freshwater Environments while the Japan Sea Has Not

Divergent selection and adaptive divergence can increase phenotypic diversification amongst populations and lineages. Yet adaptive divergence between different environments, habitats or niches does not occur in all lineages. For example, the colonization of freshwater environments by ancestral marine species has triggered adaptive radiation and phenotypic diversification in some taxa but not in others. Studying closely related lineages differing in their ability to diversify is an excellent means of understanding the factors promoting and constraining adaptive evolution. A well-known example of the evolution of increased phenotypic diversification following freshwater colonization is the three-spined stickleback. Two closely related stickleback lineages, the Pacific Ocean and the Japan Sea occur in Japan. However, Japanese freshwater stickleback populations are derived from the Pacific Ocean lineage only, suggesting the Japan Sea lineage is unable to colonize freshwater. Using stable isotope data and trophic morphology, we first show higher rates of phenotypic and ecological diversification between marine and freshwater populations within the Pacific Ocean lineage, confirming adaptive divergence has occurred between the two lineages and within the Pacific Ocean lineage but not in the Japan Sea lineage. We further identified consistent divergence in diet and foraging behaviour between marine forms from each lineage, confirming Pacific Ocean marine sticklebacks, from which all Japanese freshwater populations are derived, are better adapted to freshwater environments than Japan Sea sticklebacks. We suggest adaptive divergence between ancestral marine populations may have played a role in constraining phenotypic diversification and adaptive evolution in Japanese sticklebacks.     

Genetic and morphological evidence for cryptic diversity in the <Emphasis Type="Italic">Careproctus rastrinus</Emphasis> species complex (Liparidae) of the North Pacific

The molecular phylogeny of the Careproctus rastrinus species complex is presented on the basis of sequence variations in the 16S rRNA and cytochrome b genes (1,447 base pairs) of mitochondrial DNA using specimens collected from across the North Pacific and its marginal seas, including the Sea of Japan, the Pacific coast of Japan, the Sea of Okhotsk, the Bering Sea, the Gulf of Alaska, and the Arctic Ocean. Gene flow and migration between geographic regions is apparently strictly restricted in the C. rastrinus species complex, as this phylogeny revealed nine genetically diverged groups in the C. rastrinus species complex, most of which corresponded well with major geographic regions. Most of the groups were different in terms of morphological characters. Five nominal species have been considered to be members of the complex and have been variously recognized as being valid or as synonyms of C. rastrinus, but the present genetic and morphological differences suggested that the C. rastrinus species complex represents far more divergence. Such cryptic diversity of the C. rastrinus species complex defined by geographic regions may be related to their low dispersal ability, because they bear large demersal eggs. The genetic divergence suggested that colder climates from the late Pliocene and the isolation of marginal seas during the Pleistocene may have driven the divergence of the C. rastrinus species complex.     

Extensive Introgression of Mitochondrial DNA Found between two Genetically Divergent Forms of Threespine Stickleback, Gasterosteus Aculeatus, around Japan

The genetic structure and phylogenetic relationships of Gasterosteus aculeatus around Japan were investigated for 15 populations of the Japan Sea and Pacific Ocean forms previously detected by allozyme analyses. PCR-RFLP analysis of mtDNA ND5/6 gene indicated two major divergent clades: (1) Alaskan population and (2) Russian and Japanese populations. Japanese populations were clearly subdivided into G. aculeatus populations and hariyo (G. aculeatus leiurus). However, the relationships among Japanese G. aculeatus populations did not support the genetic divergence between Japan Sea and Pacific Ocean forms shown by allozyme analyses. This suggests that mtDNA genetype similarity between the two forms could have resulted from complete replacement of mtDNA from one form to the other. MtDNA introgression is possible in two direction: from Japan Sea form to Pacific Ocean form and the reverse. The haplotype composition of each population observed in the present study suggests that the second direction is more likely. The migrant number of females per generation (Nm) between populations of the two forms was remarkablely large (9.083–infinite), suggesting that gene flow is taking place between the populations at the present time or might have occurred until recent years.     

Population genetic structure of northern Dolly Varden char <Emphasis Type="Italic">Salvelinus malma malma</Emphasis> in Asia and North America

The level of genetic differentiation of northern Dolly Varden char Salvelinus malma malma from Asia and North America was evaluated using the data on mtDNA variation (regions ND1/ND2, ND5/ND6, and Cytb/D-loop) obtained by means of PCR-RFLP analysis. For S. m. malma, the mean values of haplo-type and nucleotide diversity were 0.5261 ± 0.00388 and 0.001558, respectively. The mean estimate of the population nucleotide divergence constituted 0.055%. It was demonstrated that S. m. malma on the most part of the species range examined (drainages of the Beaufort Sea, Chukotka Sea, Bering Sea, and the Sea of Okhotsk) was characterized by the population genetic structure with the low level of genetic differentiation and divergence. At the same time, populations from the Pacific Ocean Gulf of Alaska demonstrated marked genetic differentiation, supported by the high pairwise G4ST values (from 0.4198 to 0.5211) and nucleotide divergence estimates (mean divergence, 0.129%), from Asian and North American populations. Analysis of molecular variance (AMOVA) showed that most of the mtDNA variation in S. m. malma fell in the intrapopulation component (72.5%). At the same time, the differences between the populations (21.1%) and between the regions (6.4%) made lower contribution to the total variation.     

Genetic divergence between colonies of Flesh-footed Shearwater <Emphasis Type="Italic">Ardenna carneipes</Emphasis> exhibiting different foraging strategies

Increasing evidence suggests foraging segregation as a key mechanism promoting genetic divergence within seabird species. However, testing for a relationship between population genetic structure and foraging movements among seabird colonies can be challenging. Telemetry studies suggest that Flesh-footed Shearwater Ardenna carneipes that breed at Lord Howe Island or New Zealand, versus southwestern Australia or Saint-Paul Island in the Indian Ocean, migrate to different regions (North Pacific Ocean and northern Indian Ocean, respectively) during the non-breeding season, which may inhibit gene flow among colonies. In this study, we sequenced a 858-base pair mitochondrial region and seven nuclear DNA fragments (352–654 bp) for 148 individuals to test genetic differentiation among colonies of Flesh-footed Shearwaters. Strong genetic divergence was detected between Pacific colonies relative to those further West. Molecular analysis of fisheries’ bycatch individuals sampled in the Sea of Japan indicated that individuals from both western and eastern colonies were migrating through this area, and hence the apparent segregation of the non-breeding distribution based on telemetry is invalid and cannot contribute to the population genetic structure among colonies. The genetic divergence among colonies is better explained by philopatry and evidence of differences in foraging strategies during the breeding season, as supported by the observed genetic divergence between Lord Howe Island and New Zealand colonies. We suggest molecular analysis of fisheries’ bycatch individuals as a rigorous method to identify foraging segregation, and we recommend the eastern and western A. carneipes colonies be regarded as different Management Units.     

Population genetic structure of northern Dolly Varden char Salvelinus malma malma in Asia and North America

The level of genetic differentiation of northern Dolly Varden char Salvelinus malma malma from Asia and North America was evaluated using the data on mtDNA variation (regions ND1/ND2, ND5/ND6, and Cytb/D loop) obtained by means of PCR-RFLP analysis. For S. m. malma, the mean values of haplotype and nucleotide diversity were 0.5261 +/- 0.00388 and 0.001558, respectively. The mean estimate of the population nucleotide divergence constituted 0.055%. It was demonstrated that S. m. malma on the most part of the species range examined (drainages of the Beaufort Sea, Chukotka Sea, Bering Sea, and the Sea of Okhotsk) was characterized by the population genetic structure with the low level of genetic differentiation and divergence. At the same time, populations from the Pacific Ocean Gulf of Alaska demonstrated marked genetic differentiation, supported by the high pairwise phi(ST) values (from 0.4198 to 0.5211) and nucleotide divergence estimates (mean divergence, 0.129%), from Asian and North American populations. Nested analysis of molecular variance (AMOVA) showed that most of the mtDNA variation in S. m. malma fell in the intrapopulation component (72.5%). At the same time, the differences between the populations (21.1%) and between the regions (6.4%) made lower contribution to the total variation.     

Phylogeography and population structure of the Dall's porpoise,Phocoenoides dalli,in Japanese waters revealed by mitochondrial DNA

We investigated genetic diversity and phylogenetic relationships among three morphologically distinct populations of Dall's porpoise (Phocoenoides dalli) in Japanese waters by analyzing mitochondrial DNA variation. These populations, the Sea of Japan-Okhotsk dalli-type population, the truei-type population and the standard dalli-type population in the northwestern North Pacific, are clearly discriminated from each other by differences in the size of their white flank patch. A total of 479 bp of the mitochondrial control region and flanking tRNA genes was sequenced for 103 individuals. Haplotypic diversity was high (h = 0.968), but these haplotypes differed by only a few nucleotides (pi = 0.0106). Although many haplotypes were shared between populations, analysis of molecular variance (AMOVA) indicated genetic subdivision among the three populations (overall F (ST) = 0.023, P < 0.001; phi(ST) = 0.026, P = 0.029). Pairwise comparisons indicated a low but significant difference between the Sea of Japan-Okhotsk and the other two populations, whereas there was no significant difference between the latter. These results suggest that there is a close evolutionary relationship among these populations despite their consistent differences in coloration. This may reflect genetic polymorphism in the common ancestral population, which subsequently underwent a rapid divergence. The low genetic variability and haplotypic differentiation of the Sea of Japan-Okhotsk population suggest that it originated from a small population that colonized the Sea of Japan or that experienced population reduction when this Sea was isolated from the North Pacific in the last glacial period.     

Sex Chromosome Turnover Contributes to Genomic Divergence between Incipient Stickleback Species

Sex chromosomes turn over rapidly in some taxonomic groups, where closely related species have different sex chromosomes. Although there are many examples of sex chromosome turnover, we know little about the functional roles of sex chromosome turnover in phenotypic diversification and genomic evolution. The sympatric pair of Japanese threespine stickleback (Gasterosteus aculeatus) provides an excellent system to address these questions: the Japan Sea species has a neo-sex chromosome system resulting from a fusion between an ancestral Y chromosome and an autosome, while the sympatric Pacific Ocean species has a simple XY sex chromosome system. Furthermore, previous quantitative trait locus (QTL) mapping demonstrated that the Japan Sea neo-X chromosome contributes to phenotypic divergence and reproductive isolation between these sympatric species. To investigate the genomic basis for the accumulation of genes important for speciation on the neo-X chromosome, we conducted whole genome sequencing of males and females of both the Japan Sea and the Pacific Ocean species. No substantial degeneration has yet occurred on the neo-Y chromosome, but the nucleotide sequence of the neo-X and the neo-Y has started to diverge, particularly at regions near the fusion. The neo-sex chromosomes also harbor an excess of genes with sex-biased expression. Furthermore, genes on the neo-X chromosome showed higher non-synonymous substitution rates than autosomal genes in the Japan Sea lineage. Genomic regions of higher sequence divergence between species, genes with divergent expression between species, and QTL for inter-species phenotypic differences were found not only at the regions near the fusion site, but also at other regions along the neo-X chromosome. Neo-sex chromosomes can therefore accumulate substitutions causing species differences even in the absence of substantial neo-Y degeneration.     

Genetic evidence supporting the existence of two distinct species in the genusGasterosteus around Japan

Synopsis The genetic and morphological features ofGasterosteus aculeatus were investigated for 29 populations around Japan. Allozyme analyses recognized two groups (Pacific Ocean group and Japan Sea group) that had distinct characteristic features, and showed high genetic differentiation between them (D = 0.482). The Pacific Ocean group had a wide range, from North America to Japan, along the Pacific coast. The distribution of the Japan Sea group was limited around the Sea of Japan and the Sea of Okhotsk. The distribution of these groups were found to be sympatric on the Pacific coast of Hokkaido Island, Japan. From this area, genetic analyses demonstrated that the sympatric populations of the two groups formed independent breeding stocks, and it is considered that the two groups were reproductively isolated from each other. Additionally, each group had distinctive morphological features of lateral plates and caudal keels in the sympatric area. These results suggested that these two groups of the threespine stickleback comprise different species and that the Japan Sea group is taxonomically distinguishable fromG. aculeatus.     

Phylogeography of the flathead mullet Mugil cephalus in the north-west Pacific as inferred from the mtDNA control region

The population genetic structure and historical demography of the flathead mullet Mugil cephalus were investigated using the mtDNA control region (CR) sequences (909–1015 bp) of 126 individuals collected from seven locations in the north-west Pacific between 2005 and 2007. Haplotype diversity ( h = 0·9333–1·000) and nucleotide diversity (π = 0·0046–0·1467) varied greatly among the sampling locations. Phylogenetic analysis of the CR sequences indicated that M. cephalus in the north-west Pacific belongs to two highly divergent lineages (lineages 1 and 2), with the inferred population structure being closely associated with the distribution of both lineages. Two populations were identified, one from the East China Sea and the other from the South China Sea. The former samples were obtained from Taiwan and Qingdao of north China and associated with lineage 1 haplotypes. The latter samples were collected from the Philippines, Pearl River of South China and two samples from Japan, all of which were associated with lineage 2. Japanese samples from Okinawa and Yokosuka had different degrees of mixing between lineages 1 and 2. Historical demographic variables in both populations indicated that Pleistocene glaciations had a strong impact on M. cephalus in the north-west Pacific, resulting in a recent demographic decline of the East China Sea population but in demographic equilibrium for the South China Sea population. Japan appears to be a contact zone between lineages 1 and 2, but it may also be indicative of coexistence between resident and migratory populations. Further global studies are required to clarify the taxonomic status of this cosmopolitan species.     

Secondary contact in the Sea of Japan: the case of the <Emphasis Type="Italic">Careproctus rastrinus</Emphasis> species complex (Liparidae)

The Careproctus rastrinus species complex, widely known from the North Pacific, has been revealed recently to include nine genetically divergent groups on the basis of mitochondrial DNA (mtDNA) sequence variations. Herein we describe an AFLP analysis that focuses on three closely related groups in order to clarify the evolutionary history of the species complex in the Sea of Japan and off the Pacific coast of Japan. A principal coordinate analysis indicated the absence of nuclear divergence in two groups defined by mtDNA variations in the Sea of Japan, whereas another group from the Pacific coast of northern Japan was clearly distinct. This suggests extensive gene flow between two groups in the Sea of Japan as a result of secondary contact.     

A Review of the Sipunculan Genus Thysanocardia Fisher

The taxonomy of the sipunculan taxon Thysanocardia Fisher is reviewed. Originally erected as a subgenus of Golfingia Lankester, the status of Thysanocardia is here elevated to the level of a genus. Of the 17 species currently recognised within this genus, most of which were originally described from single specimens, only three are considered sufficiently distinct as to warrant specific status, namely T. catherinae (Grube), T. procera (Möbius) and T. nigra (Ikeda). T. catherinae is the most widespread of these species being distributed in the western North Atlantic, South Atlantic and western Indian Ocean, whilst T. procera is confined to the north-eastem region of the North Atlantic and T. nigra chiefly to the North Pacific Ocean.     

Cryptic genetic divergence within threatened species of <Emphasis Type="Italic">Acropora</Emphasis> coral from the Indian and Pacific Oceans

Most hard corals have broad distributions, and historically this was attributed to their capability for extensive dispersal leading to high evolutionary and demographic inter-dependence among regions. More recently there has been a paradigm shift in the understanding of coral dispersal, driven largely by genetic evidence, which has put greater emphasis on self-recruitment and larval retention. There is now a growing body of evidence that morphologically cryptic species exist within many recognized ‘species’ of stony corals. Here, we characterise levels of genetic divergence within and between five species of Acropora sampled from disparate populations spanning the Indo-Pacific Oceans. We find that strong regional genetic differentiation corresponding to the separation of the Indian and Pacific Ocean basins is a consistent pattern in three of the five species examined. Furthermore, the extent of allopatric divergence within species is similar to that observed between species, implying negligible contemporary gene flow between regions in four of the five species examined. This is consistent with the presence of numerous morphologically cryptic allopatric subspecies or incipient Acropora species. If this is confirmed, the conservation status of several species, which are already demonstrably threatened, would require re-evaluation so that risks including silent extinctions and inappropriate translocations are properly managed.     

Phylogeography of Bivalve Cyclina sinensis: Testing the Historical Glaciations and Changjiang River Outflow Hypotheses in Northwestern Pacific

Background

The marginal seas of northwestern Pacific are characterized by unique topography and intricate hydrology. Two hypotheses have been proposed to explain genetic patterns of marine species inhabiting the region: the historical glaciations hypothesis suggests population genetic divergence between sea basins, whereas the Changjiang River outflow hypothesis suggests genetic break in line with the Changjiang Estuary. Here the phylogeography of bivalve Cyclina sinensis was investigated to test the validity of these two hypotheses for intertidal species in three marginal seas—the East China Sea (ECS), the South China Sea (SCS), and the Japan Sea (JPS).

Methodology/Principal Findings

Fragments of two markers (mitochondrial COI and nuclear ITS-1) were sequenced for 335 individuals collected from 21 populations. Significant pairwise Φ_ST were observed between different marginal sea populations. Network analyses illustrated restricted distribution of haplogroups/sub-haplogroups to sea basins, with a narrow secondary contact zone between the ECS and SCS. Demographic expansion was inferred for ECS and SCS lineages using mismatch distributions, neutral tests, and extended Bayesian Skyline Plots. Based on a molecular clock method, the divergence times among COI lineages were estimated dating from the Pleistocene.

Conclusions

The phylogeographical break revealed for C. sinensis populations is congruent with the historical isolation of sea basins rather than the putative Changjiang River outflow barrier. The large land bridges extending between seas during glaciation allowed accumulation of mutations and subsequently gave rise to deep divergent lineages. The low-dispersal capacity of the clam and coastal oceanography may facilitate the maintenance of the historical patterns as barriers shift. Our study supports the historical glaciations hypothesis for interpreting present-day phylogeographical patterns of C. sinensis, and highlights the importance of historical glaciations for generating genetic structure of marine coastal species especially those with low-dispersal abilities in northwestern Pacific.     

Are the meiofaunal polychaetes Hesionides arenaria and Stygocapitella subterranea true cosmopolitan species? — results of RAPD‐PCR investigations

The interstitial meiofauna of sand beaches includes many species that are regarded as cosmopolites, on the basis of records from various sites throughout the world. There is a long-standing debate about the causes of such a distribution, but for most of these species it is still questionable whether they are in fact true species or 'merely' complexes of cryptic species. Here genetic differentiation is examined within and between two species considered typically cosmopolitan, Hesionides arenaria arenaria (Hesionidae) and Stygocapitella subterranea (Parergodrilidae), by RAPD-PCR analyses of specimens from diverse marine regions on two continents. For S. subterranea at three sites, on the North Sea coast (Sylt) and the US Atlantic (Massachusetts) and Pacific (Washington) coasts, with 14 primers 335 different DNA fragments were found: 20 diagnostic ones for the European animals, 17 for the animals from the American East Coast and 14 for those from the American West Coast. Five cluster procedures were used, all of which significantly distinguished the three populations as separate genetic clades; it is recommended that each be given species status. In contrast, the individual specimens of H. a. arenaria from eight European sites, between Skagerrak and the eastern Mediterranean (including the Canary Islands), and the North American Pacific coast, for which 468 different DNA fragments were amplified with 12 primers, do not form separate genetic clades. For no single population was it possible to demonstrate even one diagnostic character. Therefore the cosmopolitan nature of H. a. arenaria has been confirmed at the DNA level.     

Phylogeographic analysis reveals two periods of divergence in large-scaled redfin <Emphasis Type="Italic">Tribolodon hakonensis</Emphasis> (Pisces,Cyprinidae)

Analysis of mtDNA variation in one of the amphidromic Far Eastern redfins, Tribolodon hakonensis, revealed the presence of three considerably genetically different mtDNA phylogroups in the individuals from the Russian part of the range. These data suggest the presence of the two periods of divergent evolution in the history of the species examined. Comparison of the haplotype distributions from different phylogroups over the species range revealed geographic localization of only one phylogroup in the population samples from southern continental coastal regions of the Sea of Japan. At the same time, two other phylogroups were found in almost equal ratios in northern continental samples and near the Sakhalin Island. These results suggest that the first stage of the divergent evolution, which occured between Pliocene and Pleistocene, resulted in the formation of genetically isolated form (probably, a species) in the region of the Sea of Japan. The second, later period of divergence, probably associated with the separation of the Sea of Okhotsk from the Pacific Ocean then ended with the integration of earlier genetically separated forms into one species with the common gene pool.     

Phylogeography of the coronulid barnacle,Chelonibia testudinaria,from loggerhead sea turtles,Caretta caretta

The barnacle, Chelonibia testudinaria, is a common inhabitant of the marine turtle epibiont community and plays a key role in the development of this community. Phylogeographic analysis of 79 cytochrome c oxidase I (COX1) sequences for barnacles collected from five populations found contrasting patterns of divergence for populations in the Atlantic vs. the Pacific Ocean. Our analysis indicates that the two Pacific populations, Senri Beach, Japan and Bahia Magdalena, Mexico, were not only highly divergent from the Atlantic populations but are highly divergent from one another. We suggest that barnacles from these populations may represent cryptic species. In contrast, sequence divergence was greatly reduced among barnacles collected from Wassaw Island, GA, USA, Keewaydin, FL, USA, and Kyparissia, Pèloponnésus Island, Greece. A reduction in sequence diversity at the latter site was attributed to a recent range expansion into the Mediterranean Sea. We examined historical patterns of migration among the three Atlantic and Mediterranean populations using the program migrate. This analysis indicates a high rate of migration from Keewaydin to Wassaw Island, contrasted with a much lower rate of migration in the opposite direction. The estimated migration rate from Kyparissia to Keewaydin was also non-negligible. We suggest that the association between C. testudinaria and loggerhead turtles and the patterns of turtle migration have played key roles in the expansion of the range of C. testudinaria into the Mediterranean Sea and the subsequent patterns of barnacle migration. We further propose that the difference between ocean basins, with respect to the impact of host migration on barnacle gene flow, probably stems from the fact that host-mediated dispersal in the Atlantic depends on advanced stage juveniles and adults while any host-mediated dispersal in the Pacific would have to involve early "pelagic" stage juvenile loggerheads.     

Molecular dating of a marine species,Eriocheir japonica (Decapoda: Grapsidae), corroborates cenozoic tectonic events and sea level fluctuation

Changes of coastal topography for Cenozoic Himalayan orogeny complicated the phylogeographical structure of marine species and deepened their divergences. To test the association between divergence and Cenozoic tectonic events, we analyzed the phylogeographical structure of Eriocheir japonica by combining molecular data and geographical environment events. The four distinct lineages obtained through phylogenetic reconstruction and network analysis demonstrated the significant genetic divergence among geographical populations. Furthermore, the divergence time between E. j. japonica in Japan and E. j. sinensis in China was about 10.5–11.5 mya, which was coincident with the opening of the Sea of Japan. The north-south divergence time (15.5–17.5 mya) was in the range of the occurrence of the Himalaya movement. We hypothesize that coastal topography, including the formation of Taiwan in the Himalaya movement and the opening of the Sea of Japan, contributed to the geographical subspeciation of marine species. Mitten crabs were inferred to originate from one ancient population with the oldest haplotype H6 and subsequently divide into northern and southern populations. Furthermore, the Japan lineage derived from northern population in China for the opening of the Sea of Japan.