Population genetics of wild Siniperca knerii Garman, 1912 in China as evaluated by microsatellites

The Chinese perch Siniperca knerii Garman, 1912 is an endemic perciform freshwater fish species mainly distributed in the Yangtze River and the Pearl River of China. To evaluate their genetic diversity in these rivers, microsatellite markers were used to assess the genetic structure and genetic variability among nine wild populations of S. knerii. In this study, the 12 loci used were polymorphic, with observed heterozygosity (Ho) ranging from 0.4079 to 0.8886 and polymorphism information content (PIC) ranging from 0.4511 to 0.7146. Results showed that six populations from the Yangtze River had a higher genetic diversity than those from the three Pearl River populations. The Bayesian STRUCTURE analysis recovered genetic clusters that matched localities perfectly or the kind of ecology environment with a significant Fst between them. The findings of this research should provide useful information for management and conservation of S. knerii stocks.     

Genetic diversity of two Southern African cichlids (Oreochromis andersonii and O. macrochir) in the Zambezi and Congo River basins

Oreochromis andersonii and O. macrochir are two important cichlid species native to Southern Africa. We describe in this paper their genetic population structure in the Upper Zambezi River, Kafue River, and Lake Bangweulu representing part of the Congo and Zambezi River Basins. Microsatellite genetic markers were employed to analyse the genetic population structure of the two species using 177 tissue samples. The average allele richness of O. andersonii was higher in the Zambezi River (10.500) than in the Kafue River (9.583) though not statistically different. For O. macrochir, it was highest in the Zambezi River (11.170) followed by the Kafue River (9.781) and least in Lake Bangweulu (7.067) and their differences were significant. The gene diversity indices; gene diversity (hs), observed heterozygosity (H_O), expected heterozygosity (H_E) were high and similar in O. andersonii populations. However, in O. macrochir H_E was significantly lower in Lake Bangweulu (0.678) compared to the Kafue River (0.799) and Zambezi River (0.802) populations. Population differentiation estimated by R_ST and D_EST revealed high differentiation in both species (R_ST = 0.598, D_EST = 0.777 for O. andersonii; R_ST = 0.379, D_EST = 0.710 for O. macrochir). The highest source of variation was among populations (84.71%) for O. andersonii and within populations (67.09%) for O. macrochir. Comparisons of population pairs revealed a close genetic similarity between the Zambezi River and Lake Bangweulu populations of O. macrochir. Bottlenecks were observed in both species using the Two-Phase Model (T.P.M.) indicative of a recent genetic loss or reduction in effective population size. Though our results indicate that the populations of both species still maintain sufficiently high levels of genetic diversity in the sampled areas, the bottlenecks observed are a source of concern. We recommend a more robust study of genetic diversity of these species in all sections of these river systems and that some key conservation sites should be identified to protect the gene pool of these native species.     

Genetic Differences Between Hatchery Stocks and Natural Populations in Pacific Abalone (<Emphasis Type="Italic">Haliotis discus</Emphasis>) Estimated Using Microsatellite DNA Markers

Genetic variations within and between nine hatchery stocks and seven natural populations of abalone including Ezo-abalone (Haliotis discus hannai) and Kuro-abalone (H. d. discus) were assayed with nine microsatellite markers. Marked reductions of genetic variability in the hatchery stocks were recognized in the allelic diversity and mean heterozygosity compared with the natural populations. Thirteen of 16 significant HWE deviations in hatchery stocks revealed heterozygotes excess, while all natural populations did not show such a tendency. Highly significant F _ST values were observed for all cases between the hatchery stocks, and between the hatchery stocks and natural populations. Genetic distance (D _A) between each hatchery stock and the geographically proximal population (mean ± SD, 0.108 ± 0.035) were similar to those estimated for between the natural Ezo-abalone and Kuro-abalone (0.101 ± 0.021). The self-assignment test, which allocated individuals to their own stock with a high success rate, provided evidence of solid genetic differences among the nine hatchery stocks. These results suggests that the allelic composition and diversity in the natural populations was not necessarily reflected in the hatchery stocks owing to population bottleneck and genetic drift through seedling process, and thus the seedling and stocking practice of these hatchery stocks should take much notice of the results to conserve the genetic diversity of natural populations.     

Structure and genetic variability of golden mussel (Limnoperna fortunei) populations from Brazilian reservoirs

The golden mussel, Limnoperna fortunei a highly invasive species in Brazil, has generated productive, economical, and biological impacts. To evaluate genetic structure and variability of L. fortunei populations present in fish farms in the reservoirs of Canoas I (CANFF), Rosana (ROSFF), and Capivara (CAPFF) (Paranapanema River, Paraná, Brazil), eight microsatellite loci were amplified. Five of those eight loci resulted in 38 alleles. The observed heterozygosity (Ho) was lower than the expected heterozygosity (He) in all populations, with a deviation from the Hardy–Weinberg equilibrium (HWE). The average value for the inbreeding coefficient (Fis) was positive and significative for all populations. There was higher genetic variability within populations than among them. The fixation index (Fst) showed a small genetic variability among these populations. The occurrence of gene flow was identified in all populations, along with the lack of a recent bottleneck effect. The clustering analysis yielded K = 2, with genetic similarity between the three populations. The results demonstrate low genetic structure and suggest a founding population with greater genetic variability (ROSFF). Our data point to the possible dispersal of L. fortunei aided by anthropic factors in the upstream direction. It was concluded that the three populations presented a unique genetic pool for Paranapanema River, with occurrence of gene flow.     

Conservation genetics of the endangered endemic Sambucus palmensis Link (Sambucaceae) from the Canary Islands

Five polymorphic microsatellites (simple sequence repeat; SSR) markers were used to estimate the levels of genetic variation within and among natural populations from different islands of the endangered endemic from the Canary Islands Sambucus palmensis Link (Sambucaceae). Genetic data were used to infer potential evolutionary processes that could have led to present genetic differentiation among islands. The levels of genetic variability of S. palmensis were considerably high; proportion of polymorphic loci (P = 100%), mean number of alleles per locus (A = 6.8), average expected heterozygosity (He = 0.499). In spite of its small population size and endemic character, 58 different multilocus genotypes were detected within the 165 individuals analyzed. All samples located in different islands always presented different multilocus genotypes. Principal Coordinates Analysis, genetic differentiation analysis (F _ST and G _ST ′) and Bayesian Cluster Analysis revealed significant genetic differences among populations located in different islands. However, this genetic differentiation was not recorded among Tenerife and La Gomera populations, possibly revealing the uncontrolled transfer of material between both islands. AMOVA analysis attributed 77% of the variance to differences within populations, whereas 8% was distributed between islands. The levels of genetic differentiation observed among populations, and the genetic diversity distribution within populations in S. palmensis, indicate that management should aim to conserve as many of the small populations as possible. Concentrating conservation efforts only on the few large populations would result in the likelihood of loss of genetic variability for the species.     

Microsatellite analysis of the genetic structure of captive forest musk deer populations and its implication for conservation

Forest musk deer (Moschus berezovskii) are rare as a result of poaching for musk and habitat loss. Some captive populations of forest musk deer have been established for decades in China. However, little genetic information is available for conservation management. In this paper, genetic variations, population structures, and the genetic bottleneck hypothesis were examined using 11 microsatellite loci from captive populations in Miyalo, Jinfeng and Maerkang in Sichuan Province, China. Estimates of genetic variability revealed substantial genetic variation in the three populations. A total of 142 different alleles were observed in 121 forest musk deer and the effective number of alleles per locus varied from 6.76 to 12.95. The average values of observed heterozygosity, expected heterozygosity, and Nei's expected heterozygosity were 0.552, 0.899 and 0.894 respectively. The overall significant (P < 0.001) deficit of heterozygotes because of inbreeding within breeds amounted to 34.5%. The mean F_ST (P < 0.001) showed that approximately 90.2% of the genetic variation was within populations and 9.8% was across populations. The UPGMA diagram, based on Nei's unbiased genetic distance, indicated that the three populations were differentiated into two different groups and it agreed with their origin and history. Bottleneck tests indicated that all three populations have undergone a population bottleneck, suggesting a small effective population size. Acknowledging that the genetic structure of populations has crucial conservation implications, the present genetic information should be taken into account in management plans for the conservation of captive forest musk deer.     

Polymorphic microsatellites identified by cross-species amplifications in the European Coot Fulica atra

We tested the cross-amplification of 26 microsatellites developed for passerines and an additional three developed for Gallinula species in eight European Coots from two populations. Sixteen microsatellite markers successfully amplified, of which nine were polymorphic with 2–6 alleles (mean 3.7 alleles) and an expected heterozygosity (H _e) ranging from 0.375 to 0.805 (mean H _e = 0.589). On average, we found 2.22 alleles/locus and a mean H _e of 0.440 in one nest, and 2.56 alleles/locus and a mean H _e of 0.494 in the other one. These nine polymorphic markers could be of potential use in studies of genetic variability, population structure and reproductive strategy of European Coots.     

Genetic diversity and population structure of 10 Chinese indigenous egg-type duck breeds assessed by microsatellite polymorphism

The genetic structure and diversity of 10 Chinese indigenous egg-type duck breeds were investigated using 29 microsatellite markers. The total number of animals examined were 569, on average 57 animals per breed were selected. The microsatellite marker set analysed provided 177 alleles (mean 6.1 alleles per locus, ranging from 3 to 10). All populations showed high levels of heterozygosity with the lowest estimate of 0.539 for the Jinding ducks, and the highest 0.609 observed for Jingjiang partridge ducks. The global heterozygote deficit across all populations (F _IT) amounted to −0.363. About 10% of the total genetic variability originated from differences among breeds, with all loci contributing significantly. An unrooted consensus tree was constructed using the NeighborNet tree based on the Reynold’s genetic distance. The structure software was used to assess genetic clustering of these egg-type duck breeds. Clustering analysis provided an accurate representation of the current genetic relations among the breeds. An integrated analysis was undertaken to obtain information on the population dynamics in Chinese indigenous egg-type duck breeds, and to better determine the conservation priorities.     

Genetic Structure of Wild Rice Oryza Glumaepatula Populations in Three Brazilian Biomes Using Microsatellite Markers

The existence of Oryza glumaepatula is threatened by devastation and, thus, the implementation of conservation strategies is extremely relevant. This study aimed to characterize the genetic variability and estimate population parameters of 30 O. glumaepatula populations from three Brazilian biomes using 10 microsatellite markers. The levels of allelic variability for the SSR loci presented a mean of 10.3 alleles per locus and a value of 0.10 for the average allelic frequency value. The expected total heterozygosity (H_e) ranged from 0.63 to 0.86. For the 30 populations tested, the mean observed (H_o) and expected heterozygosities (H_e) were 0.03 and 0.11within population, respectively, indicating an excess of homozygotes resulting from the preferentially self-pollinating reproduction habit. The estimated fixation index ( _IS ) was 0.79 that differed significantly from zero, indicating high inbreeding within each O. glumaepatula population. The total inbreeding of the species (_IT ) was 0.98 and the genetic diversity indexes among populations, _ST and _ST, were 0.85 and 0.90, respectively, indicating high genetic variability among them. Thus, especially for populations located in regions threatened with devastation, it is urgent that in situ preservation conditions should be created or that collections be made for ex situ preservation to prevent loss of the species genetic variability.     

Temporal genetic changes between cohorts in a natural population of a marine fish, Diplodus sargus

Temporal changes at 17 allozyme loci in the Diplodus sargus population of Banyuls sur Mer (Mediterranean Sea, France) were monitored within a single population among ten year‐classes (cohorts) sampled over a 6‐month period. The genetic survey was combined with evaluation of the demographic structure of the population by determining variation of abundance between cohorts. The population showed variation in abundance among cohorts ranging from 16 to 214 individuals. Significant divergences in genetic structure were observed between cohorts (P < 0.0001) despite very low values of F_ST (multilocus F_ST over all cohorts = 0.0018). The heterozygosity of each cohort, as well as the F_IS values, was significantly correlated with the abundance of each cohort, with abundant cohorts showing lower heterozygosity and a significant deficit of heterozygotes (positive F_IS values). Finally, multilocus temporal genetic variance (F_k) computed between successive cohorts was higher in low abundance cohorts. Change of heterozygosity between cohorts, distribution of year‐class genetic structure, and change in the genetic structure within a cohort appear to be affected mostly by the abundance of the cohort and are therefore driven by genetic drift. We propose that the Diplodus sargus cohorts are built up from the mixing of families during the pelagic stage or later during recruitment, and that the decrease in heterozygosity leading to a deficit of heterozygotes is characteristic of a Wahlund effect. Such a Wahlund effect would derive from the mixing of the progeny of families made up of few individuals, but exhibiting high fecundity and high variability of reproductive success. Therefore, although cohorts derived from poor recruitment would only group a few families and would exhibit limited deficit of heterozygotes (higher heterozygosity values), they would lead to high genetic drift and appear more divergent (higher mean temporal genetic variance) than cohorts with high abundance. While not demonstrating directly the family structure of marine populations, our survey provides evidence of highly structured populations. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 76 , 9–20.     

Genetic Variation Analysis within and among Six Varieties of Common Carp (Cyprinus carpio L.) in China Using Microsatellite Markers

Five microsatellites were used to study the genetic diversity and genetic structure of one wild and five domestic varieties of common carp in China (the Yangtze River wild common carp, Xingguo red carp, purse red carp, Qingtian carp, Russian scattered scaled mirror carp and Japanese decorative carp). All loci in this study showed marked polymorphism with the number of alleles ranging from 4 to 13. Domestic varieties (except Xingguo red carp) showed less genetic diversity than the Yangtze River wild common carp in terms of allelic diversity. Population differentiation was assessed and each combination of populations displayed significant differentiation (P < 0.05) with the exception of that between the Yangtze River wild common carp and Xingguo red carp. Genetic distance analysis (Nei's standard genetic distance and pairwise F _st distance) showed that the largest distance was between Russian scattered scaled mirror carp and the Yangtze River wild common carp and the smallest distance was between the Yangtze River wild common carp and Xingguo red carp. However, among six populations Japanese decorative carp displayed the highest level of variability in terms of heterozygosity.     

Microsatellite Markers Reveal Genetic Variation within Sclerotinia sclerotiorum Populations in Irrigated Dry Bean Crops in Brazil

Microsatellites are powerful markers to infer population genetic parameters. We used 10 microsatellite loci to characterize the genetic diversity and structure of 79 samples of Sclerotinia sclerotiorum isolated from four Brazilian dry bean populations and observed that eight of them were polymorphic within populations. We identified 102 different haplotypes ranging from 6 to 18 per locus. Analyses based on genetic diversity and fixation indices indicated variability among and within populations of 28.79% (F_ST = 28793) and 71.21%, respectively. To examine genetic relatedness among S. sclerotiorum isolates, we used internal spacer (ITS1‐5.8S‐ITS2) restriction fragment length polymorphism (PCR‐RFLP) and sequencing analysis. PCR‐RFLP analysis of these regions failed to show any genetic differences among isolates. However, we detected variability within the sequence, which does not support the hypothesis of clonal populations within each population. High variability within and among populations may indicate the introduction of new genotypes in the areas analysed, in addition to the occurrence of clonal and sexual reproduction in the populations of S. sclerotiorum in the Brazilian Cerrado.     

Genetic divergence without spatial isolation in polecat Mustela putorius populations

Understanding how genetic divergence could exist without spatial isolation is a fundamental issue in biology. Although carnivores have previously been considered as having a weak genetic variability, polecats Mustela putorius from eight distinct populations exhibited both a strong polymorphism (17.5–22.5%) and a substantial allele effective number reaching N_e=1.12. Heterozygosity ranging from H_o=0.031–0.063 significantly differed among populations, while the mean F_IS averaging 0.388 stressed a real deficiency of heterozygotes. Observed heterozygosity levels among populations did not correlate with any habitat types but were clearly associated with habitat diversity index. The habitat structure in polecat home range corresponded to habitat mosaic structure in which discrete habitat types alternated causing multifactorial constraints that may favour heterozygosity. Allozymic frequencies within populations did not vary with dominant habitat. But in the Tyrosinase‐1, the rare homozygote BB, resulting in a ‘dark’ phenotype, was found much more in deciduous woods than the homozygote AA showing the ‘typical’ pattern. Thus, the genetic basis for a character differentiation was here evidenced in a remarkable situation without spatial isolation. Further, the very low proportion of heterozygotes for this locus suggests a disruptive effect and supports the prediction of intermediate phenotypes being at a disadvantage. This heterozygote deficit may also result from an assortative mating intra phenotype (homogamy). The divergence in polecat phenotypes showed that genetic differentiation can be induced by subtle variations in environment, a situation that is likely to be frequent in most natural populations, and emphasized the adaptive nature of habitat preference.     

Genetic variation of wild litchi (<Emphasis Type="Italic">Litchi chinensis</Emphasis> Sonn. subsp. <Emphasis Type="Italic">chinensis</Emphasis>) revealed by microsatellites

Understanding the amount and distribution of genetic diversity in natural populations can inform the conservation strategy for the species in question. In this study, genetic variation at eight nuclear microsatellite loci was used to investigate genetic diversity and population structure of wild litchi (Litchi chinensis Sonn. subsp. chinensis). Totally 215 individuals were sampled, representing nine populations of wild litchi. All eight loci were polymorphic, with a total of 51 alleles. The expected heterozygosity in the nine populations ranged from 0.367 to 0.638 with an average value of 0.526. Inbreeding within wild litchi populations was indicated by a strong heterozygote defect. Significant bottleneck events were detected in the populations from Yunnan and Vietnam, which could be responsible for lower levels of genetic diversity in these populations. Measures of genetic differentiation (F _ST = 0.269) indicated strong differentiation among wild litchi populations. Significant correlation was found between genetic differentiation and geographical distance (r = 0.655, P = 0.002), indicating a strong isolation by distance in these populations. Bayesian clustering suggested genetic separation among three regional groups, namely, the western group, the central group and the eastern group. Some conservation strategies for wild litchi populations were also proposed based on our results.     

Genetic variation within and between populations of hermaphroditic <Emphasis Type="Italic">Bulinus truncatus</Emphasis> tetraploid freshwater snails of the Albertine Rift,East Africa

Genetic variability within and among Bulinus truncatus of the Albertine Rift freshwater bodies were assessed to investigate the degree of inbreeding and gene flow in the snail populations. The effect of ploidy on the genetic structuring of B. truncatus is also described. We characterized the genetic structure of seven B. truncatus populations from Lake Albert, Lake Kivu, and Katosho swamp in Tanzania using five polymorphic microsatellite loci. Genetic differentiation was quantified using pairwise FST values and Nei’s standard genetic distances. Different alleles were observed across all loci and genetic diversity was low although it varied greatly across populations; observed heterozygosity was, however, higher than the expected heterozygosity in three of the populations studied. Significant heterozygote deficiencies were observed coupled with significant linkage disequilibria in five populations for all the five loci examined in this study. We found significant genetic differentiation among the seven freshwater bodies; private alleles were observed across all loci indicating restricted or absence of gene flow between populations. Limited snail dispersal and the reproductive biology of B. truncatus are the major forces shaping the genetic variation observed. Low genetic variation within B. truncatus populations exposes them to a high parasite infection risk as predicted in the Red Queen hypothesis.     

Microsatellite DNA markers indicate three genetic lineages in East Asian indigenous goat populations

The genetic differentiation and phylogenetic relationships of 18 indigenous goat populations from seven East Asian countries were analysed based on data obtained from 26 microsatellite DNA markers. The mean number of alleles (MNA) per population ranged from 2.5 to 7.6, with an average of 5.8. Genetic variability estimated from MNA and heterozygosity (H_E and H_O) were relatively low in coastal and island populations. A heterozygous deficiency within populations (F_IS = 0.054, P < 0.001) and total inbreeding (F_IT = 0.181, P < 0.01) were observed, and genetic differentiation in the populations (F_ST) was 13.4%. The results of Bayesian model‐based clustering and a neighbour‐joining tree based on Nei's genetic distance showed that Asian goat populations could be subdivided into at least the following three genetic clusters: East Asian, Southeast Asian and Mongolian. These results are in close accordance with conventional morphological and geographical classifications and migration history.     

Genetic variation of blood proteins within and between local populations of grivet monkey (Cercopithecus aethiops aethiops) in central Ethiopia

A population genetic study by blood protein electrophoresis revealed that populations of wild grivet monkeys in central Ethiopia show a comparatively low level of variability and less differentiation among local populations over broad geographical areas. This is evaluated by comparison with other wild primate studies using the same electrophoretic technique. A total of 196 blood samples, collected from 10 local populations comprising 11 troops distributed along approximately 600 km of the Awash River, were examined for 33 genetic loci. The low level of variability was indicated by the proportion of polymorphic loci (P_poly), which was on average 11% with an average heterozygosity (H) of 3%. A tendency for lower genetic differentiation among local populations was shown by theG _ST value of 0.09, an averageF _ST of 0.08, andNei's genetic distance; ranging from 0.002 to 0.023. Considering paleoclimatological studies of the area and ecological traits of this species, these findings can be explained as a consequence of a comparatively recent and repeated series of rapid habitat expansions following severe climatic conditions.     

Genetic diversity and population differentiation in the yellow drum Nibea albiflora along the coast of the China Sea

Nibea albiflora (yellow drum) is an important seafood fish species in East Asia. We explored the population genetic variation of N. albiflora along the coastal waters of the China Sea using microsatellite markers to facilitate a selective breeding programme that is undertaken in China. A total of 256 alleles were detected at 12 loci in four wild populations. A high level of genetic diversity was observed with the mean number of alleles and the observed and expected heterozygosity in each population ranging from 7.917 to 14.083, 0.701 to 0.764 and 0.765 to 0.841, respectively. Pairwise fixation index (F_ST) analysis indicated significant but weak genetic differentiation among populations from four localities (F_ST?=?0.030, P?<?0.01), which was also confirmed by analysis of molecular variance (AMOVA). Significant genetic differentiation was detected between Ningde and the other populations (F_ST?=?0.047–0.056, P?<?0.01). Structure analysis suggested that N. albiflora within the examined range might be composed of two stocks. The data of the present study revealed high genetic diversity and low genetic differentiation among the N. albiflora populations along the coast of the China Sea. This baseline information could be valuable for future selective breeding programmes of N. albiflora.     

Population genetic inferences using immune gene SNPs mirror patterns inferred by microsatellites

Single nucleotide polymorphisms (SNPs) are replacing microsatellites for population genetic analyses, but it is not apparent how many SNPs are needed or how well SNPs correlate with microsatellites. We used data from the gopher tortoise, Gopherus polyphemus—a species with small populations, to compare SNPs and microsatellites to estimate population genetic parameters. Specifically, we compared one SNP data set (16 tortoises from four populations sequenced at 17 901 SNPs) to two microsatellite data sets, a full data set of 101 tortoises and a partial data set of 16 tortoises previously genotyped at 10 microsatellites. For the full microsatellite data set, observed heterozygosity, expected heterozygosity and F_ST were correlated between SNPs and microsatellites; however, allelic richness was not. The same was true for the partial microsatellite data set, except that allelic richness, but not observed heterozygosity, was correlated. The number of clusters estimated by structure differed for each data set (SNPs = 2; partial microsatellite = 3; full microsatellite = 4). Principle component analyses (PCA) showed four clusters for all data sets. More than 800 SNPs were needed to correlate with allelic richness, observed heterozygosity and expected heterozygosity, but only 100 were needed for F_ST. The number of SNPs typically obtained from next‐generation sequencing (NGS) far exceeds the number needed to correlate with microsatellite parameter estimates. Our study illustrates that diversity, F_ST and PCA results from microsatellites can mirror those obtained with SNPs. These results may be generally applicable to small populations, a defining feature of endangered and threatened species, because theory predicts that genetic drift will tend to outweigh selection in small populations.     

The impact of Yangtze River discharge on the genetic structure of a population of the rock bream,Oplegnathus fasciatus

As a rocky reef species, Oplegnathus fasciatus displays significant geographic differences that may be congruent with patterns of molecular variation. We used 10 polymorphism microsatellite loci to characterize the genetic structure and test the impact of ocean currents and the Yangtze River on the population genetic connectivity of the rock bream, O. fasciatus, sampled from Jiaonan (JN), Zhoushan (ZS) and Taiwan (TW). The average number of alleles was 17.78, with a total of 160 alleles, and the average allele value in the East China Sea (ZS?=?13.70) was higher than that in the Yellow Sea (JN?=?6.70). The individuals at the ZS location showed the highest expected heterozygosity (He?=?0.86), Nei's genetic diversity (H?=?0.84) and Shannon genetic diversity (I?=?2.21). Genetic bottleneck tests showed that individuals had experienced a recent bottleneck effect in the JN location. AMOVA analysis showed that 12.19% of genetic variation existed among populations, indicating significant population genetic differentiation in the species. The values of the population pairwise differentiation index (F_st and Φ_pt) ranged from 0.01 to 0.29. The UPGMA tree showed two diverged genealogical branches corresponding to sampling localities (Clade A?=?JN, Clade B?=?ZS and TW) in the species. The AMOVA and STRUCTURE analyses suggested that O. fasciatus may be composed of two stocks in the examined range, and the freshwater discharge from the Yangtze River might act as a physical barrier to genetic exchange between north and south China stocks of the species.