Phylogenetic Relationships of 12 Penaeoidea Shrimp Species Deduced from Mitochondrial DNA Sequences

Phylogenetic Utility of Mitochondrial COI and Nuclear Gpdh Genes in Drosophila

A freshwater mussel, Nodularia breviconcha (Mollusca: Bivalvia: Unionida) is endemic to Korean Peninsula. It has recently been taxonomically reexamined and elevated from a subspecies of N. douglasiae to an independent species. But population genetic studies for the species have rarely been conducted. To explore the population genetic structure of N. breviconcha, the nucleotide sequences of cytochrome oxidase subunit I(COI) and 16S rRNA genes from 135 N. breviconcha individuals, including 52 from this study and 83 from Choi et al. (2020). We found 23 COI and 11 16S rRNA genes haplotypes. Phylogeny, TCS network, Principal coordinates analysis, and spatial analysis of molecular variance performed with COI gene indicated that there are exist three different genetic lineages in the N. breviconcha populations: West lineage, Southwest lineage, and Southeast lineage. According to the time calibrated phylogeny, they are likely to be diverged during the late Miocene (8-6 Ma). Geographical distribution patterns of the three genetic lineages may be related to the formation of Taebaek and Sobaek-Noryeong mountain ranges in the Korean Peninsula occurred during the Miocene (30-10 Ma). The present results of this study will be helpful not only for the conservation, but also for the exploration of the population genetic structure of endemic freshwater mussels in the Korean Peninsula.

INTRODUCTIONMainly distributed in the Bohai Sea and the Yellow Sea, Penaeus chinensis shrimpis of economic importance in both fishing and seafarming industries in China. Inrecent years, the sustainable development of the P. chinensis fishery industry hasbeen threatened by overfishing, viral epizootics, and habitat contamination. Aninvestigation of the genetic variation within this species may shed light on theprotection and genetic enhancement of the species.Very high genetic variation of mitochondrial cytochrome oxidase subunit I(COI)genehasbeenobservedinseveralspeciesofarthropods(Meyranetal.,1997;Navajas et al., 1998, 1999). In the genus Penaeus, although insufficient studies onmtDNA have been reported, large genetic variations of the COI gene have beendetected among 15 species (Baldwin et al., 1998; Palumbi and Benzie, 1991),and 0–3% COI variation was observed within somePenaeus species (Baldwinet al., 1998). High genetic variations of mitochondrial 16s rRNA gene have alsobeen observed within P. notialis, and between P. notialis and P. schmitti (Garcia-Machado et al., 1993). In this study, therefore, we sequenced COI and 16s rRNAgenes to investigate genetic variation in P. chinensis populations.

AMPLIFICATION OF COI GENE FROM SNAKE BLOOD SAMPLES USING TWO UNIVERSALPRIMER PAIRS. This study aims to amplify COI (Cytochrome Oxidase Subunit I) gene fragments from snake blood. Four samples were obtained from four different snake individuals that were captured in Tapahan Telu Waterfall, Kali Village, Minahasa Regency. Total DNA from the sample was isolated and then the COI gene was amplified through the PCR (Polymerase Chain Reaction) reaction using two primer pairs, LCO1490-HCO2198 and FF2d-FR1d. These four samples were successfully amplified using different primers, i.e. DRP1 and DRP3 by FF2d-FR1d and DRP2 and DRP4 by LCO1490-HCO2198 primers. The success of amplification marked by the presence of 710 bp (LCO1490-HCO2198) and 707 bp (FF2d-FR1d) bands, which were indicated by those bands were located close to the standard 750 bp DNA ladder. Key words: Snake, Amplification, COI gene, Primers, PCR

Mutations in mitochondrial DNA (mtDNA) play an important role in the development of prostate cancer, according to research by scientists at Emory University School of Medicine and the University of California, Irvine . The findings were published online in January, 2005 in the Proceedings of the National Academy of Sciences (PNAS). Mitochondrial DNA, which is separate from nuclear DNA, is found in the hundreds of mitochondria located in the cytoplasm outside of each cell's nucleus. The mitochondria often are called the "powerhouse" of the cell because they produce about 90 percent of the body's energy.John A. Petros, MD, associate professor of urology and pathology at Emory University School of Medicine and the Winship Cancer Institute, and Douglas C. Wallace, PhD, director of the Center for Molecular and Mitochondrial Medicine and Genetics at the University of California, Irvine, sequenced segments of mtDNA from prostate cancer patients and found a variety of mutations, including various mutations in the mtDNA cytochrome oxidase subunit (COI) gene. They then sequenced the COI gene in 260 prostate cancer tissue samples or blood cells from patients with confirmed cancer who had undergone radical prostatectomies between 1995 and 2002, and 54 tissue samples from patients who had prostate biopsies but were found to be cancer free. Twelve percent of all the prostate cancer samples had mutations in the COI gene, while less than 2 percent of the samples from patients found to be cancer free harbored mutations in this gene. In a control sample of 1,019 individuals from the general population, 7.8 percent had mutations in the COI gene. The researchers found both germ-line (inherited) and somatic (acquired) mutations in the prostate cancer samples.Because COI mutations are known to be more common in individuals of African descent, the scientists also analyzed a group of patients and controls of European ancestry. In this group they found the COI mutations in 11 percent of the prostate cancer specimens, in 0 percent of the no-cancer group and in 6.5 percent in a general population sample of 898 Europeans.To determine whether mtDNA mutations are causally related to prostate cancer, the researchers introduced into a prostate cancer cell line mtDNAs harboring a known disease-causing mtDNA mutation and, as a control, the same mtDNA but without the disease mutation. They then injected these modified prostate cancer cells into mice to assess their tumor-forming ability. The prostate cancer cells with the mutant mtDNAs generated tumors that were on average seven times larger than the prostate cancer cells with normal mitochondria. Hence, the deleterious mtDNA mutation greatly enhanced prostate cancer growth.Since mitochondria make oxygen radicals as a by-product of making energy, and oxygen radicals can stimulate cell growth, the researchers then tested the tumors for oxygen radical production. The tumors with the mutant mtDNAs generated significantly more oxygen radicals than those with normal mtDNAs, suggesting that this may be an important contributory factor in the mitochondrial enhancement of prostate cancer growth.Because the study found that COI mutations were common in the general population (7.8 percent), but very infrequent (

为了对比线粒体16S rRNA和COI基因片段在长江口虾虎鱼科鱼类种类鉴定和系统分类研究中的适用性，本文运用PCR技术，扩增了虾虎鱼科7属8种24个个体的线粒体16S rRNA和COI基因片段，并对其种间的序列差异进行比较分析。经比对后得到16S rRNA基因长度为535bp的序列，共编码178个氨基酸，24条16S rRNA序列共有12个单倍型，共检测到变异位点161个，约占总位点数的30.1%，插入/缺失位点15个，转换与颠换比值(Si/Sv)为1.51；同时，获得COI基因长度641 bp，共编码213个氨基酸，单倍型个数与16S rRNA序列相同，变异位点221个，所占百分比高于16S rRNA序列(约34.5%)，无插入/缺失位点，转换/颠换值为1.29。两种基因的转换/颠换值均小于2，因此对其做了相应的突变饱和性分析，结果显示，两种基因在虾虎鱼科鱼类中不存在突变饱和现象。遗传距离结果显示，16S rRNA基因种间序列变异程度均小于COI基因，16S rRNA基因的种内和种间平均遗传距离分别为0.002和0.169，种间约为种内遗传距离的84倍，种间遗传距离最小值存在于纹缟虾虎鱼和髭缟虾虎鱼之间为0.100；而COI序列的种内和种间平均遗传距离分别0.001和0.215，种间为种内遗传距离的215倍。因此，16S rRNA和COI序列均适用于虾虎鱼科的种类鉴定。基于16S rRNA和COI基因序列获得的UPGMA系统树显示虾虎鱼科鱼类均可形成单系群，不同之处在于16S rRNA基因序列主要表现种、属间序列差异，而COI则突出表现种、属、科间序列差异。因此，在应用这两种基因片段做系统分类研究时，应根据研究的不同系统水平选择适当的分子标记。 In order to compare the applicability of mitochondrial 16S rRNA and COI (mitochondrial cytoch-rome oxidase subunit I) in species identification and phylogeny of Gobiidae from Yangtze Estuary, this study investigated the genetic characteristics of these two gene fragments. The two gene fragments of 8 species in Gobiidae were amplified by PCR, and the sequence variation among in-terspecies was analyzed. A total of 535 bp, 12 haplotypes, 161 variation sites (about 30.1% of all), 15 insertion or deletion of sites were detected for 16S rRNA of 24 individuals, and 178 amino acids were encoded. All of the transitional pairs (si) was slightly more than that of the transversional pairs (sv), and the ratio (R = si/sv) was 1.51; while 641 bp and 221 variation sites were detected for COI, and no insertion or deletion of sites was found in the COI gene, the ratio of si and sv was 1.29. Both the ratios of the two genes from 24 individuals were less than 2, so mutation saturation of the two genes was analyzed. However, the result showed that there was no mutation saturation in the two genes of Gobiidae. The results of genetic distance showed that the degree of variation of 16S rRNA in interspecific sequence was less than that of COI sequence. Intraspecific and interspecific K2P genetic distances were respectively 0.002 and 0.169 for 16S rRNA sequences, and 0.001 and 0.215 for COI sequences. Genetic differences of 16S rRNA sequences between congeners were, on average, about 84 times higher than the differences within species, and the minimum value (0.100) was existed between Tridentiger trigonocephalus and Tridentiger barbatus; while genetic differences of COI sequences were 215 times between intraspecies and interspecies, which met Hebert’s species identification standard (more than 10 times the difference between intraspecies and interspecies). Therefore, 16S rRNA and COI sequences were both applicable for species identi-fication in Gobiidae. The UPGMA phylogenetic tree was constructed based on 16S rRNA and COI, which demonstrated that Gobiidae in the Yangtze Estuary was a monophyletic group. The major differences were that interspecies and genera were more emphasis for 16S rRNA gene, while it highlighted interspecies, genera and family more for COI gene. As a result, it is advisable to select appropriate molecular markers according to different classified levels when applying the two gene fragments for studying species identification and phylogeny.

Abstract. Hakim AA, Dikrurahman, Muhlis S, Astuti RP, Sari DW, Kamal MM. 2022. A genetic approach for authentication on morphological differences of cultivated pompano species in Indonesia. Biodiversitas 23: 4561-4569. Due to the increasing demand for animal protein, the Batam Marine Cultivation Fisheries Center (BPBL Batam) developed pompano (Trachinotus spp.) for aquaculture. Because of the different external characteristics, local communities recognized three types of pompano, i.e., bintang, emas, andhibridpompano. The study aimed to prove the authenticity of cultivated pompano (Trachinotus spp.) with morphological differences based on a DNA barcoding approach with 16S ribosomal RNA and cytochrome oxidase subunit I (COI) partial genesequences. A total of 30 barcode sequences from COI and 16S rRNA genes were obtained from three types of pompano, and all samples were validated as Trachinotus blochii with percent identity of 99.85-100% by COI and 100% by 16S rRNA. Emas, bintang, and hibrid pompano also have the same or very similar GC content both based on COI and 16S rRNA sequences. The average genetic distances calculated between species in the genusTrachinotus were 0.09 and 0.02 among COI and 16S rRNA sequences, respectively. Phylogenetic analysis constructed from COI and 16S rRNA gene sequences of all types of pompano and related species segregated genus into one clade (T. blochii) and the outgroup (other species) as another clade. This study contributed essential genetic data to the NCBI database both COI and 16S rRNA gene sequences. Despite having morphological differences, all types of pompano were successfully authenticated into the same species because they have identical nucleotide base arrangements and can be presumed from the same ancestor.

BackgroundIdentifying species of organisms by short sequences of DNA has been in the center of ongoing discussions under the terms DNA barcoding or DNA taxonomy. A C-terminal fragment of the mitochondrial gene for cytochrome oxidase subunit I (COI) has been proposed as universal marker for this purpose among animals.ResultsHerein we present experimental evidence that the mitochondrial 16S rRNA gene fulfills the requirements for a universal DNA barcoding marker in amphibians. In terms of universality of priming sites and identification of major vertebrate clades the studied 16S fragment is superior to COI. Amplification success was 100% for 16S in a subset of fresh and well-preserved samples of Madagascan frogs, while various combination of COI primers had lower success rates.COI priming sites showed high variability among amphibians both at the level of groups and closely related species, whereas 16S priming sites were highly conserved among vertebrates. Interspecific pairwise 16S divergences in a test group of Madagascan frogs were at a level suitable for assignment of larval stages to species (1–17%), with low degrees of pairwise haplotype divergence within populations (0–1%).ConclusionWe strongly advocate the use of 16S rRNA as standard DNA barcoding marker for vertebrates to complement COI, especially if samples a priori could belong to various phylogenetically distant taxa and false negatives would constitute a major problem.

PDF HTML阅读 XML下载 导出引用 引用提醒 基于线粒体COI基因的部分鲇形目鱼类系统发育研究 DOI: 作者: 作者单位: 1. 中国水产科学研究院珠江水产研究所, 农业农村部热带亚热带水产资源利用与养殖重点实验室, 广东 广州 510380;2. 上海海洋大学 水产与生命学院, 上海 201306 作者简介: 陈海港(1989-),男,硕士研究生,研究方向为种质资源与遗传育种.E-mail:harborchen89@163.com 通讯作者: 中图分类号: S917 基金项目: 科技部科技基础性工作专项（2013FY110700）；中国水产科学研究院中央级公益性科研院所基本科研业务费专项（2014A11）. Phylogenetic analysis of catfish (Siluriformes) based on the mitochondrial COI gene Author: Affiliation: 1. Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China;2. College of Fisheries and Life, Shanghai Ocean University, Shanghai 201306, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:本文选择COI基因片段作为分子标记，对部分鲇形目鱼类（Siluriformes）进行系统发育研究。应用通用引物PCR扩增得到13种鲇形目鱼类的134条COI基因，并与GenBank中获得15种鲇形目鱼类的51条COI基因进行比对分析。结果显示：鲇形目鱼类COI基因存在碱基插入缺失现象较少，为越南隐鳍鲇（Pelteobagrus fulvidraco）3种共计5个位点；平均碱基含量A+T（55.5%）显著高于G+C（44.5%）。利用Kimura’s 2-parameter计算28个物种的种间平均遗传距离为0.195，23个物种的种内平均遗传距离为0.006。系统发育树的分析结果表明，Neighbour-Joining（NJ）树较Maximum Likelihood（ML）树更为适合鲇形目鱼类的遗传发育分析；COI基因在科及其以下水平的系统进化关系与传统分类方法所认同的结果一致性较高，达到82.9%以上；在目水平的一致性的可信度较低，仅为71%；半鲿属聚为单系类群，黄颡鱼属、鮠属和拟鲿属三者聚为一支，黄颡鱼属与拟鲿属的亲缘关系较近。 Abstract:Catfish, important economic fishes, account for about one-third of the freshwater fishes globally, and are widely distributed with abundant species and population structures in China. Owing to limited bones in the muscle and good taste, catfishes are widely consumed and occupy an important position in the aquatic products market. In this study, using the COI (cytochrome oxidase subunit I) gene fragment as a molecular marker, phylogenetic analyses were carried out on some catfish species. A total of 134 sequences of 13 species of catfishes were amplified using universal primers, and the results were compared with 51 other sequences belonging to 15 species of catfishes obtained from GenBank. The results showed that Pelteobagrus fulvidraco included five insert-deletion sites. The average base A+T (55.5%) was significantly higher than that of G+C (44.5%). The average genetic distance of 28 pairwise and 23 within species were determined as 0.195 and 0.006, respectively using Kimura's 2-parameter (MEGA6.0). The phylogenetic tree analysis showed that a neighbor-joining tree was more suitable than the maximum likelihood tree for the genetic analysis of the catfish species. According to neighbor-joining tree for all 185 sequences of catfishes, the consistency with traditional taxonomy on family levels and below was higher (82.9%) than that of order levels (71%). Samples of each species formed highly supported monophyletic groups. The neighbor-joining tree showed that species of come from the same branch, and the . The results of this study showed that the COI gene could be used as a molecular assistive tool for the identification of catfish species, and could also be applied to molecular phylogenetic relationships. The results effectively expanded the species classification information of catfishes, and provided necessary evidence for traditional taxonomy. 参考文献 相似文献 引证文献

BackgroundThe morphotaxonomy of Rhipicephalus microplus complex has been challenged in the last few years and prompted many biologists to adopt a DNA-based method for distinguishing the members of this group. In the present study, we used a mitochondrial DNA analysis to characterise the genetic assemblages, population structure and dispersal pattern of R. microplus from Southeast Asia, the region where the species originated.MethodsA phylogeographic analysis inferred from the 16S rRNA and cytochrome oxidase subunit I (COI) genes was performed with five populations of R. microplus collected from cattle in Malaysia. Malaysian R. microplus sequences were compared with existing COI and 16S rRNA haplotypes reported globally in NCBI GenBank.ResultsA total of seven and 12 unique haplotypes were recovered by the 16S rRNA and COI genes, respectively. The concatenated sequences of both 16S rRNA and COI revealed 18 haplotypes. Haplotype network and phylogenetic analyses based on COI+16S rRNA sequences revealed four genetically divergent groups among Malaysian R. microplus. The significantly low genetic differentiation and high gene flow among Malaysian R. microplus populations supports the occurrence of genetic admixture. In a broader context, the 16S rRNA phylogenetic tree assigned all isolates of Malaysian R. microplus into the previously described African/the Americas assemblage. However, the COI phylogenetic tree provides higher resolution of R. microplus with the identification of three main assemblages: clade A sensu Burger et al. (2014) comprises ticks from Southeast Asia, the Americas and China; clade B sensu Burger et al. (2014) is restricted to ticks that originated from China; and clade C sensu Low et al. (2015) is a new genetic assemblage discovered in this study comprising ticks from India and Malaysia.ConclusionsWe conclude that the R. microplus complex consisting of at least five taxa: R. australis, R. annulatus, R. microplus clade A sensu Burger et al. (2014), R. microplus clade B sensu Burger et al. (2014) and the new taxon, R. microplus clade C sensu Low et al. (2015). The use of COI as the standard genetic marker in discerning the genetic assemblages of R. microplus from a broad range of biogeographical regions is proposed.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0956-5) contains supplementary material, which is available to authorized users.

Drosophila mercatorum is a species of neotropical origin. It is represented by two subspecies, marcatorum and pararepleta. Synanthropic subspecies D. mercatorum mercatorum spread into Eurasia in the mid-20th century, and to date, it is widespread over the territory of Europe and the former Soviet Union. The experiments were performed using the specimens of D. m. mercatorum from natural Asian populations, laboratory stock 2328 of D. mercatorum (displaying some morphological differences from Asian wild-type flies), the specimens of D. busckii and D. virilis, and the COI gene sequence of D. mercatorum from NCBI database, accession number, DQ471607. The specimens were investigated for the variability of the standard DNA sequences used for species identification (the cytochrome oxidase subunit I (COI) gene fragment and the ITS1–ITS2 region of rRNA genes). Sequences of the COI gene fragment from Asian D. m. mercatorum were identical between the specimens, but differed from the sequences of stock 2328, as well as from the NCBI sequence. Asian populations of D. mercatorum and stock 2328 were identical in the ITS1–ITS2 sequences. Low sequence divergence between the COI gene fragments, along with the absence of differences at the ITS1–ITS2 region of the rRNA genes indicate that the difference between the Asian populations of D. m. mercatorum and morphologically different stock 2328 are within the frames of intraspecies divergence.

PDF HTML阅读 XML下载 导出引用 引用提醒 基于DNA条码基因的鳢科鱼类系统进化与物种鉴定 DOI: 作者: 作者单位: 1. 中国水产科学研究院珠江水产研究所, 农业农村部热带亚热带水产资源利用与养殖重点实验室, 广东 广州 510380;2. 中国水产科学研究院长江水产研究所, 湖北 武汉 430223;3. 中国水产科学研究院黑龙江水产研究所, 中国水产科学研究院特殊生境鱼类种质特性与抗逆育种重点实验室, 黑龙江 哈尔滨 150001;4. 上海海洋大学 水产与生命学院, 上海 201306 作者简介: 赵建(1982-),副研究员,研究方向为种质资源与遗传育种.E-mail:zj.8286@163.com 通讯作者: 中图分类号: S917 基金项目: 科技基础性工作专项（2013FY110700）；现代农业产业技术体系专项资金（CARS-46）；中国水产科学研究院中央级公益性科研院所基本科研业务费专项（2014A11）；广州市珠江科技新星专项（201710010174）. Phylogenetic and species identification analysis on the snakeheads (Channidae) based on the DNA barcoding sequence Author: Affiliation: 1. Key Laboratory of Tropical & Subtropical Fishery Resource Application & Cultivation, Ministry of Agriculture and Rural Affairs;Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China;2. Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China;3. Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin 150001, China;4. College of Fisheries and Life, Shanghai Ocean University, Shanghai 201306, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:鳢科（Channidae）鱼类在亚洲分布广泛，其中中国的土著种类是重要养殖品种，国外很多种类主要作为观赏鱼引进我国。本研究利用线粒体COI基因序列，对分布于我国的鳢科鱼类不同种群样本序列，及在GenBank中获得其他鳢科鱼类的序列进行分析，探讨其作为DNA条形码基因对鳢科进行物种鉴定和系统进化分析的可行性。通过对本研究采集的149个鳢样本和122条GenBank中已有序列进行分析，结果显示，所研究的鳢科鱼类的COI基因576 bp片段中不存在碱基插入缺失现象，其平均碱基含量A+T（51.4%）高于G+C含量（48.6%），存在偏倚性；多态位点占47.2%。利用Mega 6.0软件基于Kimura’s 2-parameter模型计算25种鳢种内平均遗传距离为0.028，其中巴卡鳢（）种内遗传距离最大，为0.137，超过了某些种间遗传距离；种间遗传距离为0.030~0.302，平均为0.217。其中最大距离0.302为饰鳍鳢（）之间，甚至超过了与外群之间的距离。利用邻接法（Neighbour-Joining，NJ）和最大似然法（Maximum Likelihood Tree，ML）分别构建系统进化树，同种个体获得较高支持率，而不同种间的关系支持率较低，同时发现存在由多个种组成的巴卡鳢和南鳢复合支系。本研究表明，进行我国土著鳢科鱼类物种鉴定时COI基因是有效的工具，而进行外来观赏鱼鉴定，尤其是巴卡鳢、斯氏鳢等物种进行鉴定时，需结合多方面信息；COI基因不适合鳢科鱼类种间遗传进化关系的研究。 Abstract:Snakeheads are of important cultural value as ornamental fishes in China. In this study, the mitochondrial COI (cytochrome oxidase subunit I) gene fragments 576 bp long were used to analyze the phylogenetic and diversity of snakeheads in and out of China, to probe the probability of the COI gene to be used as a barcoding sequence for species identification. Including 149 specimens of different geographic populations of native to China, and 122 sequences of other species downloaded from GenBank, a total of 271 snakehead individuals of 25 species, were analyzed. Of all the sequences, no insertion-deletion sites existed. The average content of A+T (51.4%) was higher than that of G+C (48.6%). The average intraspecies genetic distance was 0.028, but reached 0.137 in , which was higher than some interspecies distances. The interspecies distances ranged from 0.030 to 0.302, with an average of 0.217. The largest distance exists between , exceeding some distances to outgroup. Phylogenetic trees based on the neighbor-joining and maximum likelihood method were constructed. Most individuals from the same species formed a monophyly, and high bootstrap values were obtained for them, but this was not the case for several other species. However, the relationships of species have low bootstrap values, indicating improper phylogenetic analysis of the COI gene for snakeheads. Furtherly, a compound were formed according to the phylogenetic trees. The results of this research indicate that the COI gene is proper for the species identification of native species of snakeheads in China, but more information regarding imported ornamental snakeheads is needed. 参考文献 相似文献 引证文献

Based on the data of the shrimp resources sampled by single trawler as investigation boat in 18 stations in the offshore waters of the Mid-Southern East China Sea (26°00'N—28°30'N,121°00'E—126°00'E) in May,August,November,2006 and February,2007,total catch from each trawler was counted and identified to species in taxonomy,and the spatial variation of the shrimp species composition,index of relative importance (IRI),the diversity and similar characteristics of the community structure were analyzed. 32 species of shrimp were caught in this survey,which belonged to 22 families under 11 genera. Comparison of the amounts of various species in different seasons:there are 22 species in the autumn which are the most; 20 species in winter,17 and 18 species in the spring and the summer respectively. According to the standard of index of relative importance (IRI) (the species with IRI above 1000 were regarded as the dominant species in this paper),there were 10 dominant species:Metapenaeopsis longirostris,Metapenaeopsis dalei,Solenocera alticarinata,Plesionika izumiae,Ibacus novemdentatu,Parapenaeus fissuroides,Solenocera koelbeli,Solenocera crassicornis,Parapenaeopsis hardwickii and Solenocera crassicornis,and 5 of them were major dominant species which were Metapenaeopsis longirostris,Metapenaeopsis dalei,Plesionika izumiae,Parapenaeus fissuroides and Parapenaeopsis hardwickii. Defined the ones with IRI values ranging from 100 to 1000 as common species,we got 7:Metapenaeopsis barbata,Penaeus japonicus,Plesionika dentirostris,Palaemon gravieri,Alpheus japonicus,Parapandalus spinipes and Sicyonia cristata. The abundance of the dominant species was varied with seasons. For example,5 were in May:Metapenaeopsis longirostris,Metapenaeopsis dalei,Parapenaeopsis hardwickii,Solenocera alticarinata and Plesionika izumiae,89.15% of the total catch and 92.14% of the total individuals. In August,there were 7 dominant species:Metapenaeopsis dalei,Plesionika izumiae,Metapenaeopsis longirostris,Parapenaeus fissuroide,Solenocera crassicornis,Ibacus novemdentatus and Solenocera alticarinata,91.82% of the total catch and 95.05% of the total individuals. In November,the number of dominant species increased to 8:Metapenaeopsis longirostris,Plesionika izumiae,Parapenaeus fissuroides,Metapenaeopsis dalei,Solenocera crassicornis,Ibacus novemdentatus,Solenocera koelbeli and Solenocera alticarinata,occupying 95.31% and 97.56% of the total catch individuals,respectively. In February,the number reduced to 5:Metapenaeopsis longirostris,Parapenaeus fissuroides,Metapenaeopsis dalei,Solenocera koelbeli and Plesionika izumiae,88.76% and 94.93% respectively. Based on their adaptability to habitats,all recorded species of shrimps were categorized into the hyperthermal and hysaline community in the Mid-Southern East China Sea. The stations with high abundance were mainly located in the west of the 120m isobaths,and gradually lower toward the autumn to winter,while it reached the lowest in winter. Margalef index (D) and Shannon-Wienner index (H') were higher in summer and autumn than those in winter and spring,Pielou's evenness index (J') in the offshore waters of the Mid-Southern East China Sea was stable through every season. The result indicated that the diversity index west of the 120m isobaths was higher than in the east. By hierarchical cluster analysis and non-metric multidimensional scaling (NMDS) assisted analyzing,the types of shrimp assemblage determined by influential factor such as aquatic system,water mass and salinity etc. in the East China Sea in spring were also discussed in the article,two main assemblages were identified in the offshore waters of the Mid-Southern East China Sea,which were deeper costal shrimp assemblage and out shelf sea shrimp assemblage.

In order to identify the phylogenetic relationship among three Nemipterus species(N.japonicus,N.ne-murus and N.mesoprion) caught from Beibu Gulf,we amplified their mitochondrial cytochrome oxidase subunit I(COI) gene fragments by PCR,and examined 696 base-pair nucleotide sequences of COI.The results show that all 48 sequences are grouped into 29 haplotypes and there are 104 variable nucleotide positions in COI gene frag-ments.Haplotypes analysis indicates that N.japonicus and N.nemurus have obvious gene flow and closer rela-tionship and have no significant genetic difference based on sequence divergences and genetic distances analysis.Molecular phylogenetic trees are constructed with Scolopsis taenioptera and Eucinostomus currani as outgroups using maximum-parsimony and neighbor-joining,which suggests that the three Nemipterus species cluster into two clades.Specifically,N.japonicus and N.nemurus cluster into one clade,while N.mesoprion into another.Thus,it could be concluded that the relationship between N.japonicus and N.nemurus is so close that they may be the same species,while the relationship between N.mesoprion and N.japonicus and that between N.mesoprion and N.nemurus in pairwise is far,which provides molecular biology evidence that N.nemurus and N.mesoprion are two different species.

Morphometric analysis of commercially important penaeid shrimps from the Zhujiang estuary, China