The Occurrence of an Exotic Bisexual Artemia Species, Artemia franciscana, in Two Coastal Salterns of Shandong Province, China

The alien halophilous Artemia species, Artemia franciscana, was found in Chengkou Saltern and Yangkou Saltern of Shandong Province, P.R. China. Although the indigenous parthenogenetic Artemia is detectable, the exotic species is dominant in both salterns. The cross-breeding tests between the exotic A. franciscana and 5 bisexual Artemia species were conducted. The results of hybridization and morphological observations on the exotic A. franciscana are briefly presented in this short communication.     

Revealing an Invasion Risk of Fish Species in Qingdao Underwater World by Environmental DNA Metabarcoding

Environmental DNA(eDNA)metabarcoding has emerged as a potentially powerful tool to monitor invasive fish species.As an alternative(or complementary)tool for biodiversity monitoring,e DNA metabarcoding had been used to detect species in aquariums,which represents an important transit avenue for introducing non-indigenous species with high population densities.In this study,eDNA metabarcoding as well as morphological characterization were used to reveal the diversity of non-indigenous species in a large aquarium at Qingdao Underwater World.Environmental DNA metabarcoding of 14 water samples at five locations from the Big Water Tank detected 24 non-indigenous species and four putative non-indigenous operational taxonomic units(OTUs).In contrast,only 20 non-indigenous species were observed by morphological characterization.Some species undetected by morphological characterization,such as Oreochromis niloticus(Linnaeus,1758),are highly adaptable to various environments and/or have invaded preferred regions where they threaten native aquatic species.eDNA metabarcoding also detected seven local fishes that were not identified by morphological characterization.However,analysis of OTU diversity among stations and sample replications revealed that eDNA varied within and/or between stations.Increasing sampling effort as well as negative controls are required to increase the detection rate of species and to eliminate false-positive OTUs.     

Genetic diversity in two Japanese flounder populations from China seas inferred using microsatellite markers and COI sequences

Japanese flounder is one of the most important commercial species in China; however, information on the genetic background of natural populations in China seas is scarce. The lack of genetic data has hampered fishery management and aquaculture development programs for this species. In the present study, we have analyzed the genetic diversity in natural populations of Japanese flounder sampled from the Yellow Sea (Qingdao population, QD) and East China Sea (Zhoushan population, ZS) using 10 polymorphic microsatellite loci and cytochrome c oxidase subunit I (COI) sequencing data. A total of 68 different alleles were observed over 10 microsatellite loci. The total number of alleles per locus ranged from 2 to 9, and the number of genotypes per locus ranged from 3 to 45. The observed heterozygosity and expected heterozygosity in QD were 0.733 and 0.779, respectively, and in ZS the heterozygosity values were 0.708 and 0.783, respectively. Significant departures from Hardy-Weinberg equilibrium were observed in 7 of the 10 microsatellite loci in each of the two populations. The COI sequencing analysis revealed 25 polymorphic sites and 15 haplotypes in the two populations. The haplotype diversity and nucleotide diversity in the QD population were 0.746±0.072 8 and 0.003 34±0.001 03 respectively, and in ZS population the genetic diversity values were 0.712±0.047 0 and 0.003 18±0.000 49, respectively. The microsatellite data (F_st =0.048 7, P<0.001) and mitochondrial DNA data (F_st =0.128, P<0.001) both revealed significant genetic differentiation between the two populations. The information on the genetic variation and differentiation in Japanese flounder obtained in this study could be used to set up suitable guidelines for the management and conservation of this species, as well as for managing artificial selection programs. In future studies, more geographically diverse stocks should be used to obtain a deeper understanding of the population structure of Japanese flounder in the China seas and adjacent regions.     

Genetic diversity and population structure of Eleutheronema rhadinum in the East and South China Seas revealed in mitochondrial COI sequences

Eleutheronema rhadinum is a potential commercial fisheries species and is subject to intense exploitation in China. Knowledge on the population structure of E. rhadinum in Chinese coastal waters, which is important for sustainable exploitation and proper resource management, is lacking. In the present study, the genetic diversity and population structure of E. rhadinum were evaluated using a 564-base pair fragment of the mitochondrial cytochrome c oxidase subunit I （COl） gene. A total of 76 specimens were collected from three localities around the East （Qidong and Zhoushan） and South China Seas （Zhuhai）. Among these individuals, nine polymorphic sites were detected and 1 l distinct haplotypes were defined. High levels ofhaplotype diversity （h=0.759i0.035） and low levels of nucleotide diversity （re=0.001 98i0.003 26） were observed in these populations, Hierarchical analysis of molecular variance （AMOVA） indicated that 96.72% of the genetic variation occurred within the populations, whereas 3.28% occurred among populations. No significant genealogical branches or clusters were recognized on the neighbor-joining tree. Intra-group variation among populations was significant （~0~t=0.032 85, P〈0.01）. These results suggest that E. rhadinum populations in the East and South China Seas have developed divergent genetic structures. Tests of neutral evolution and mismatch distribution suggest that E. rhadinum may have experienced a population expansion. The present study provides basic information for the conservation and sustainable exploitation of this species.     

Genetic diversity of populations and clones of Rhopilema esculentum in China based on AFLP analysis

Amplified fragment length polymorphisms(AFLP) markers were developed to assess the genetic variation of populations and clones of Rhopilema esculentum Kishinouye(Scyphozoa,Rhizostomatidae).One hundred and seventy-nine loci from 56 individuals of two hatchery populations and two wild populations were genotyped with five primer combinations.The polymorphic ratio,Shannon’s diversity index and average heterozygosity were 70.3%,0.346 and 0.228 for the white hatchery population,74.3%,0.313,and 0.201 for the red hatchery population,79.3%,0.349,and 0.224 for the Jiangsu wild population,and 74.9%,0.328 and 0.210 for the Penglai wild population,respectively.Thus,all populations had a relatively high level of genetic diversity.A specific band was identified that could separate the white from the red hatchery population.There was 84.85% genetic differentiation within populations.Individual cluster analysis using unweighted pair-group method with arithmetic mean(UPGMA) suggested that hatchery populations and wild populations could be divided.For the hatchery populations,the white and red populations clustered separately;however,for the wild populations,Penglai and Jiangsu populations clustered together.The genetic diversity at the clone level was also determined.Our data suggest that there are relatively high genetic diversities within populations but low genetic differentiation between populations,which may be related to the long-term use of germplasm resources from Jiangsu Province for artificial seeding and releasing.These findings will benefit the artificial seeding and conservation of the germplasm resources.     

The Clam Cyclina sinensis (Gmelin) Phylogeography Study with 28S rRNA Gene and Potential of Nuclear rRNA Genes in Genetic Assessments of Molluscs

Intraspecific diversity of molluscan species is usually studied based on maternally inherited mitochondrial DNA,from which only part of the evolutionary history can be reflected.Some nuclear ribosomal RNA genes such as 28S rRNA represent poten-tial candidates that can be easily applied in phylogeography because of lacking intraindividual variation.However,considering their low polymorphism,genetic appraisals on whether and how they can be used in population studies are necessary.Here,we applied a short 28S rRNA to assess genetic patterns of the clam Cyclina sinensis along the coast of China and compared the results with a for-mer study based on COI and ITS-1 analyses.The results revealed the 28S rRNA data set was characterized by an extremely low level of variation,with only seven haplotypes defined for 93 individuals.Haplotype and nucleotide diversity for each population was al-most the lowest when compared with the other two markers.However,the distribution of two dominant haplotypes showed clear geo-graphic patterns,and significant population differentiation was revealed between the East China Sea and the South China Sea.These patterns were highly concordant with findings of the former study that populations of C.sinensis were historically separated by land bridges among sea basins.Our study suggested that although the nuclear rRNAs have shortcomings such as low variation,they have advantages including lack of intraindividual variation and high amplification rates.Applying rRNA genes can enrich the toolbox of nuclear markers in molluscan phylogeographic studies.     

A new record of ponyfish <Emphasis Type="Italic">Deveximentum megalolepis</Emphasis> (Perciformes: Leiognathidae) in Beibu Gulf of China

A new record ponyfish, Deveximentum megalolepis Mochizuki and Hayashi, 1989, was documented based on its morphological characteristics and DNA barcode. Fifty specimens were collected from Beibu Gulf of China and identified as D. megalolepis by morphological characterization. The coloration, meristic traits, and morphometric measurements were consistent with previously published records. In general, it is a silver-white, laterally compressed and deep bodied ponyfish with 6–9 rows of scales on cheek; scale rows above lateral line 6–8; scale rows below lateral line 14–17. Mitochondrial cytochrome oxidase I subunit (COI) gene fragment was sequenced for phylogenetic analysis. There is no sequence variation of COI gene between the specimens collected in this study. The genetic distances between D. megalolepis and other congeneric species range from 3.6% to 14.0%, which were greater than the threshold for fish species delimitation. The COI sequence analysis also supported the validity of D. megalolepis at genetic level. However, the genetic distance between Chinese and Philippine individuals was about 1.2% and they formed two lineages in gene tree, which may be caused by the geographical distance.     

The occurrence of an exotic bisexual Artemia species, Artemia franciscana , in two coastal salterns of Shandong Province, China

The alien halophilous Artemia species, Artemia franciscana, was found in Chengkou Saltern and Yangkou Saltern of Shandong Province, P.R. China. Although the indigenous parthenogenetic Artemia is detectable, the exotic species is dominant in both salterns. The cross-breeding tests between the exotic A. franciscana and 5 bisexual Artemia species were conducted. The results of hybridization and morphological observations on the exotic A. franciscana are briefly presented in this short communication.     

Genetic structure and demographic histories of two sympatric Culter species in eastern China

Geographic isolation is a key factor in shaping the genetic structure of many fish species.Two sympatric species,Culter alburnus and C.mongolicus,are economically important fish that are widely distributed in China and have been recently used as new aquaculture species.We used the mitochondrial DNA control region(CR) as a marker to investigate the genetic structure of the two species.Phylogenetic analysis revealed two major lineages(Lineages I and II) that were highly consistent with geographical patterns for C.alburnus and C.mongolicus.Based on genetic distance,the Zhujiang(Pearl) River Basin(ZRB) populations potentially represented a cryptic subspecies,which might be differentiated as the result of strict geographic isolation,an earlier diverged event,or peripheral areas.Genetic diversity analysis suggested that the Changjiang(Yangtze) River Basin(CRB) populations are located at,or near the core region of their origination,not only due to the larger population size at the CRB,but also their habitat diversity and suitability for its survival,and the genetic diversity dif ferences among basin populations were significant for the two species.Moreover,demographic analysis indicated that the two Culter species and most populations had undergone a period of population expansion during warm interglacial periods.However,the C.alburnus population of Huaihe River Basin(Weishan Lake) exhibited different patterns during the interglacial period,which may due to the latest diverged time of HRB and Weishan Lake located at the permafrost.Notably,the ZRB(in Songtao Reservoir) C.mongolicus population showed no genetic diversity and had a unique haplotype,which could be treated as a special gene pool for species conservation.In summary,geographic isolation is most likely responsible for the two Culter species distribution patterns.     

Biodiversity and invasibility: Distribution patterns of invasive plant species in the Himalayas,Nepal

Invasive plant species are exerting a serious threat to biological diversity in many regions of the world. To understand plant invasions this study aims to test which of the two plant invasiveness hypotheses; ‘low native diversity' vs. ‘high native diversity', is supported by the regional distribution patterns of invasive plant species in the Himalayas,Nepal. This study is based on data retrieved from published literatures and herbarium specimens. The relationship between invasive plant species distribution patterns and that of native plant species is elucidated by scatter plots, as well as by generalized linear models. The native plant species and invasive plant species have similar distribution patterns and the maximum number of invasive plant species is found in the same altitudinal range where the highest richness for native tree species is found. There is a clear trend of higher invasive plant richness in regions where native tree species richness is relatively high.Consequently, the native plant richness is highest in the central phytogeographic region, followed by the eastern and the western regions, respectively. The invasive plant species also follows a similar trend.Additionally, the invasive plant species richness was positively correlated with anthropogenic factors such as human population density and the number of visiting tourists. This study supports the hypothesis that ‘high native diversity' supports or facilitates invasive plant species. Further, it indicates that nativeand invasive plant species may require similar natural conditions, but that the invasive plant species seem more dependent and influenced by anthropogenic disturbance factors.     

胡子鲇3个养殖群体遗传结构的AFLP分析

应用AFLP方法,从64对引物中筛选出5对用于分析胡子鲇(Claris fuscus)厦门(XM)、江门(JM)、玉林(YL)等3个养殖群体共90个个体群体内、群体间遗传多样性。扩增共得到289条清晰谱带,引物多态性介于47.8%～63.8%,平均多态性比率为56.4%。胡子鲇群体总遗传杂合度(Ht)、遗传分化系数(Hs)、遗传分化度(Gst)和基因流(Nm)分别为0.161 1、0.153 6、0.051 1和8.501 8,表明胡子鲇多态性处于中等偏下水平,群体内部遗传分化系数较高,三个群体间无较大分化,群体间基因流动较好。其中,JM群体多态性比率、有效等位基因数Ne、Nei’s指数和Shannon指数都较XM群体和YL群体高,种内分化程度较好。对群体进行两两比较发现,XM群体和YL群体间分化程度最大,XM群体和JM群体次之,JM群体和YL群体最小。基于杂交优势,推断XM和YL群体繁殖所产生的后代将具有比亲代更为优良的性状。     

Significant population genetic structure detected in the rock bream Oplegnathus fasciatus(Temminck & Schlegel,1844) inferred from fluorescent-AFLP analysis

Oplegnathus fasciatus(rock bream) is a commercial rocky reef fish species in East Asia that has been considered for aquaculture.We estimated the population genetic diversity and population structure of the species along the coastal waters of China using fluorescent-amplified fragment length polymorphisms technology.Using 53 individuals from three populations and four pairs of selective primers,we amplified 1 264 bands,98.73% of which were polymorphic.The Zhoushan population showed the highest Nei's genetic diversity and Shannon genetic diversity.The results of analysis of molecular variance(AMOVA) showed that 59.55% of genetic variation existed among populations and 40.45% occurred within populations,which indicated that a significant population genetic structure existed in the species.The pairwise fixation index F_(st) ranged from 0.20 to 0.63 and were significant after sequential Bonferroni correction.The topology of an unweighted pair group method with arithmetic mean tree showed two significant genealogical branches corresponding to the sampling locations of North and South China.The AMOVA and STRUCTURE analyses suggested that the O.fasciatus populations examined should comprise two stocks.     

The loss of genetic diversity during captive breeding of the endangered sculpin, Trachidermus fasciatus, based on ISSR markers: implications for its conservation

Inter-simple sequence repeat (ISSR) markers were used to determine the genetic variation and genetic differentiation of cultured and wild populations of Trachidermus fasciatus, an endangered catadromous fish species in China. Six selected primers were used to amplify DNA samples from 85 individuals, and 353 loci were detected. Relatively low genetic diversity was detected in the cultured population (the percentage of polymorphic loci PPL = 73.80%, Nei’s gene diversity h = 0.178 2, Shannon information index ...     

Genetic Variation and Differentiation in Wide Ranging Populations of Razor Clam （Sinonovacula constricta） Inferred from AFLP Markers

The genetic variation and differentiation of the razor clam Sinonovacula constricts distributed along the coast of China were studied through amplified fragment length polymorphism(AFLP)analysis. Six primer combinations generated 193 fragments. The He values varied from 0. 322 to 0. 463 and the percentage of polymorphic loci ranged from 74. 1% to 98. 4%, which indicates a high level of genetic diversity. Cluster analysis by Nei's pairwise distance grouped all specimens by geographical origins. AMOVA consistently showed that genetic variation among populations was 8. 71%, and most of the variation came from the genetic variation within populations(91.29%). Genetic differentiation among the six populations was moderate; pairwise FST ranged from 0. 0282 to0. 1480, which indicated that S. Constricts populations along the coast of China are genetically connected. Among all the six populations, the Beihai population is the mostly differentiated from the others, suggesting that Hainan Island and Leizhou Peninsula act as barriers to gene flow. All populations abide isolation by distance model as indicated by Mantel test, except for ZS(Zhoushan)and YQ(Yueqing)populations. Information obtained in this study will provide guidelines for conservation and fishery management of this species in the future.     

近江牡蛎3个种群生化遗传变异的研究

用同工酶电泳方法研究广东省官渡、阳江和汕尾的近江牡蛎(Ostea rivularis)的遗传变异。分析了11种同工酶20个的位点,其中出现13个位点显示为多态。结果表明官渡、阳江、汕尾种群的多态位点比例分别为0.200、0.200、0.500。官渡和阳江种群间,官渡和汕尾种群间以及阳江和汕尾种群间的遗传距离(D)分别为0.0451,0.1125,0.1088。     

Mitochondrial DNA control region diversity and population structure of Pacific herring (Clupea pallasii) in the Yellow Sea and the Sea of Japan

To investigate the genetic variation and population structure of Pacific herring in the Yellow Sea and the genetic differentiation between the Yellow Sea and the Sea of Japan,fragments of 479-bp mitochondrial DNA control region were sequenced for 110 individuals collected from three different periods in the Yellow Sea and one locality in the Sea of Japan.High haplotype diversity and moderate nucleotide diversity were observed in Pacific herring.AMOVA and exact test of population differentiation showed no significant genetic differentiations among the three populations of the Yellow Sea and suggested the populations can be treated as a single panmictic stock in the Yellow Sea.However,a large and significant genetic differentiation(WST50.11;P50.00) was detected between the populations in the Yellow Sea and the Sea of Japan.The high sea water temperature in the Tsushima Strait was thought a barrier to block the gene exchange between populations of the two sea areas.The neutrality tests and mismatch distribution indicated recent population expansion in Pacific herring.     

Significant population genetic structure detected in the rock bream <Emphasis Type="Italic">Oplegnathus fasciatus</Emphasis> (Temminck &amp; Schlegel, 1844) inferred from fluorescent-AFLP analysis

Oplegnathus fasciatus (rock bream) is a commercial rocky reef fish species in East Asia that has been considered for aquaculture. We estimated the population genetic diversity and population structure of the species along the coastal waters of China using fluorescent-amplified fragment length polymorphisms technology. Using 53 individuals from three populations and four pairs of selective primers, we amplified 1 264 bands, 98.73% of which were polymorphic. The Zhoushan population showed the highest Nei’s genetic diversity and Shannon genetic diversity. The results of analysis of molecular variance (AMOVA) showed that 59.55% of genetic variation existed among populations and 40.45% occurred within populations, which indicated that a significant population genetic structure existed in the species. The pairwise fixation index F _st ranged from 0.20 to 0.63 and were significant after sequential Bonferroni correction. The topology of an unweighted pair group method with arithmetic mean tree showed two significant genealogical branches corresponding to the sampling locations of North and South China. The AMOVA and STRUCTURE analyses suggested that the O. fasciatus populations examined should comprise two stocks.     

Application of AFLP markers for population genetic study on half-smooth tongue sole Cynoglossus semilaevis

The genetic diversity of wild and hatchery populations of half-smooth tongue sole Cynoglossus semilaevis, based on observation of amplified fragment length polymorphism (AFLP) was described. Two hundred individuals from four wild populations, Laizhou (LZ), Weihai (WH), Qingdao (QD), Rizhao (RZ), and one hatchery population, Mingbo (MB), were screened using eight different AFLP primer combinations. A total of 384 loci were screened in the five studied populations. 48.4%, 51.3%, 50.7%, 49.3% and 45.8% of these loci were polymorphic among the individuals tested in the LZ, WH, QD, RZ and MB populations, respectively. The number of polymorphic loci detected by single primer combinations ranged from 17 to 35. The average heterozygosity of the LZ, WH, QD, RZ and MB populations was 0.072, 0.093, 0.092, 0.090 and 0.063, respectively. The WH population showed the highest genetic diversity in terms of total number of AFLP bands, total number of polymorphic bands, average heterozygosity and percentage of low frequency (0-0.2) polymorphic loci among all the populations, while the LZ population was the lowest among the wild populations. Compared with the wild populations, the hatchery population showed a low genetic viability.     

Genetic improvement on Chinese shrimp （Fenneropenaeus chinensis）： growth and viability performance in F1 hybrids of different populations

Fenneropenaeus chinensis distributed in the Yellow Sea and Bohai Sea of China and the west coast of the Korean Peninsula. Different geographical populations represent potentially different genetic resources. To learn further the characteristics of different geographical population, crosses among two wild and three farmed populations were produced. The two wild populations were from the Yellow Sea and Bohai Sea (WYP), and the west coast of the Korean Peninsula and coast (WKN). The three farmed populations included the offspring of first generation of wild shrimp from coast in Korea (FKN), the Huang Hai (the Yellow Sea in Chinese) No. 1 (HH 1), and JK98. The phenotypes growth and survival rates of these populations were compared to confirm the feasibility for crossbreeding. The body length (BL), carapace length (CL), carapace width (CW), height of the second and third abdominal segment (HST), width of the second and third abdominal segment (WST), length of the first abdominal segment (LF), length of the last abdominal segment (LL), live body weight (BW), and survival rate were measured. Different combinations were statistically performed with ANOVA and Duncan's Multiple significant difference (P<0.05) in BL, CL, HST, LL, and BW; and insignificant difference (P0.05) in other growth traits and survival rate. The results of Duncan's Multiple Range Test are that BL and CL of was the best combination in all growth traits. Therefore, hybridization can introduce the variation to base populations. The systematic selection program based on additive genetic performance may be more effective than crossbreeding.