基于线粒体COI序列的DNA条形码在中国海口足类物种鉴定中的应用分析

中国海口足类动物区系具有丰富的物种多样性,是我国海洋底栖生物中的重要经济类群。口足类的属内种间鉴别特征有的极为相似,仅依靠传统的形态分类方法很难对近缘种和疑难种进行准确的鉴定。DNA条形码技术可以弥补传统形态学鉴定的某些局限,为物种鉴定提供了有效的工具。该研究探讨了利用线粒体COI序列对中国海口足类进行物种鉴定的可行性,共获得口足目4总科6科24属38个种的204条线粒体COI序列,与Gen Bank收录的14种42条口足类同源序列进行比对,结果显示口足类COI基因不存在碱基插入缺失现象,碱基组成偏倚明显,A+T含量(63.5%)显著高于G+C含量(36.5%)。基于Kimura双参数模型计算遗传距离,结果显示遗传距离随着分类阶元的增高而增大。同物种种内个体间的遗传距离变化范围在0%~3.91%,平均值为0.76%。同属内各物种间的遗传距离变化范围为6.55%~18.99%,平均值为12.91%。同科内不同属间的遗传距离变化范围为9.16%~23.32%,平均值为16.89%。不同科间的遗传距离变化范围为16.52%~26.6%,平均值为21.31%。由此可见,口足类COI基因的种间和种内遗传距离存在明显的间隙。基于COI序列构建的口足类邻接关系树显示所有包含大于1个个体的物种均可形成单系群,且节点支持率均为100%。本研究证明了COI序列作为DNA条形码标准基因在口足类物种鉴定中的有效性。此外,研究发现中国沿海分布的口虾蛄可能至少存在两个隐存种,实证了基于COI序列的DNA条形码技术能够用于口虾蛄隐存多样性的探究。

Are Acila divaricata and Acila mirabilis One Species or Two Distinct Species? Evidence from COI Mitochondrial DNA

Acila divaricata （Hinds, 1843） and A. mirabilis （Adams and Reeve, 1850） are common benthic bivalves in China. A number of researchers have proposed that the latter species is a junior synonym of the former species. Because of morphological similarities, it is difficult to distinguish these two species based on visual examination only. For better understanding of their taxon-omy, the mitochondrial CO1 gene fragments of five individuals of A. divaricata from the East China Sea and six individuals of A. mirabilis from the Yellow Sea were sequenced in this study. The phylogenetic relationships of the obtained COI sequences, together with nineteen sequences of three species of the genus Nucula, were analyzed. The pairwise intra- and inter-specific distances for the CO1 sequences ranged from 0.002 to 0.017 and from 0.128 to 0.134, respectively, and no overlap was found. Phylogenetically, A. divaricata and A. mirabilis form distinct clades and cluster into a sister to all other Nucula species. The results indicated that A. di-varicata and A. mirabilis are two distinct species. The differences in the morphology and distribution between the two species were briefly discussed.

Molecular phylogeny of the genus Clibanarius(Decapoda: Anomura: Diogenidae) based on mitochondrial and nuclear DNA sequences

Clibanarius , a genus of hermit crabs, is one of the most diverse genera within Diogenidae. However, studies on the phylogeny within Clibanarius is very limited. We reconstruct the molecular phylogeny of the genus Clibanarius based on two mitochondrial (16S rRNA and COI) and two nuclear protein-coding (NaK and PEPCK) genes using a multigene phylogenetic approach. Eleven selected Clibanarius species from the Indo-West Pacifi c are analyzed and the Bayesian and maximum likelihood analyses produced identical results in topology. Results suggest that C . rutilus and C . infraspinatus are more closely related to each other than to C . snelliusi , and C . striolatus shows a close relationship to C . longitarsus . The close association of C . merguiensis with C . englaucus and C . humilis is strongly supported by the divergence of C . virescens from them. Our phylogenetic results contradict the morphological classifi cation scheme proposed for Clibanarius and indicate that the relative length of dactyls and propodi is not phylogenetically signifi cant in Clibanarius . In addition, we speculate that the morphological characteristic of the median cleft of the telson might be phylogenetically important for Clibanarius .

Complete mitochondrial genomes of two deep-sea pandalid shrimps,Heterocarpus ensifer and Bitias brevis:insights into the phylogenetic position of Pandalidae(Decapoda:Caridea)

The mitochondrial genome(mitogenome)analysis is a significant tool for investigating the evolutionary history of metazoan animals.The family Pandalidae is a diverse caridean group containing mainly deep-sea species.Until May 302019,only two complete mitogenomes are available in GenBank.Here we present the complete mitogenome sequences of two deep-sea pandalid shrimps,Heterocarpus ensifer and Bitias brevis through Illumina sequencing.The mitochondrial genomes were determined to be 15939 bp and 15891 bp long,and both consist of 13 protein-coding genes(PCGs),23 transfer-RNA genes(tRNAs),two ribosomal-RNA genes(rRNAs),and one control region.The nucleotide composition is biased toward adenine and thymine.Overall,the gene contents and arrangements are consistent with the pancrustacean ground pattern.The alignment of the control regions of four pandalids reveals a conserved sequence block(CSB)(104 bp in length,average GC%=29.47%and 69.23%similarity).A phylogenetic analysis based on 51 Caridea complete mitogenomes revealed that the deep-sea pandalid shrimps are situated an intermediate lineage,with a tendency to originated from those living in shallow sea area.

A Preliminary Phylogenetic Analysis of Luidia (Paxillosida: Luidiidae) from Chinese Waters with Cytochrome Oxidase Subunit I (COI) Sequences

Luidia Forbes （Paxillosida： Luidiidae） are common soft bottom sea stars with 49 described species. Because of substan- tial morphological diversity, the taxonomy of the genus is complex and hasn＇t been resolved definitely. In order to resolve general taxonomic issues, and determine species boundaries and phylogenetic relationships within the genus Luidia, the sequences of tyro- chrome oxidase subunit I （COI） gene from 24 specimens of Luidia, belonging to eight taxa in Chinese waters, were studied. Three sequences of two species in genus Luidia from GenBank were used to analyze the phylogenetie relationships. The molecular phy- logeny exhibited three main clades, each with strong bootstrap support： Clade A including Luidia quinaria from the Sea of Japan; Clade B including seven nominal species （L. quinaria von Martens, L. yesoensis Goto, L. ehangi Liu, Liao and Li, L. orientalis Fisher, L. avicularia Fisher, L. longispina Sladen and L. hardwicki Gray） from Chinese waters; and Clade C including L. maculata Miiller ＆ Troschel from Chinese waters. Our molecular phylogeny results support the morphological Quinaria-Group and Alter- nata-Group assigned by D6derlein. Seven nominal species we sampled do not exhibit genetic distances that are large enough to rec- ognize them as separate species. Cryptic species may exist in ＇Luidia quinaria＇ from the Yellow Sea and the Sea of Japan. Meaning- ful morphological characters need further investigation in Luidia.

The Taxonomic Status of Japanese Threadfin Bream Nemipterus japonicus(Bloch, 1791)(Perciformes: Nemipteridae) with a Redescription of this Species from the South China Sea Based on Morphology and DNA Barcodes

Because of its importance as a food source, Nemipterus japonicus （Bloch, 1791） （Nemipteridae） or Japanese threadfin bream is the best studied of these taxa, and numerous investigations have examined its fisheries, its biology and biochemistry. De- spite such intensive work, the taxonomic status of N. japonicus has never been seriously questioned and it is regarded as a common species, widely distributed throughout the Indo-Westem Pacific Ocean. In fact, Bloch＇s description of the type specimen of N.ja- ponicus has ambiguous collection data and lacks a designation for the type locality, though it is probably Java. In this paper, DNA barcode results based on COl gene support the existence of two geographically separated lineages of the Japanese threadfin bream, both being an Indian Ocean and western Pacific lineage, with 2.7% sequence divergence, and the results indicate a possible existing of some cryptic species. The two lineages also possess a diagnostic difference in their belly color, with specimens in the South China Sea having a silver belly, while those from the Indian Ocean isolate specimen have a yellow coloration. Based upon new collections from the South China Sea, this species from the western Pacific is morphologically redescribed and its details of DNA barcode diver- sity are shown for the future investigations.

构建自立自强的海洋科学观测探测技术体系的思考

海洋是国家战略必争领域,建设海洋强国必须要提高海洋资源开发能力,发展海洋经济,保护海洋生态环境,坚决维护国家海洋权益。推动海洋科技实现高水平科技自立自强,是加快建设海洋强国的必然要求。海洋观测探测技术是认识海洋的基本手段,是海洋资源开发、环境保护和权益维护的重要基础。文章回顾了全球和我国海洋观测探测计划和观测网络取得的重要进展,重点介绍了中国科学院海洋科学观测探测技术体系构建的实践,并对下一步发展提出了思考和展望。构建自立自强的海洋科学观测探测技术体系,要进一步加强顶层设计,推动国家战略需求和科技前沿问题“双引擎”;强化科技攻关,瞄准最紧急、最紧迫的关键问题持续发力;创新体制机制,充分发挥海洋领域国家战略科技力量作用,为我国海洋强国建设提供强有力的科技支撑。

Complete mitochondrial genome of the Japanese snapping shrimp Alpheus japonicus(Crustacea:Decapoda:Caridea):Gene rearrangement and phylogeny within Caridea

The complete sequence of the mitochondrial genome of the Japanese snapping shrimp Alpheus japonicus Miers （Crustacea： Decapoda： Caridea） is presented here. A comparative analysis based on the currently available mitochondrial genomic data re- vealed many previously unknown characteristics of the mitochondrial genomes of caridean shrimps. The A. japonicus mito- chondrial genome is 16487 bp long and contains the typical set of 37 metazoan genes. The gene arrangements in the mito- chondrial genomes of four previously studied carideans （Macrobrachium rosenbergii, M. nipponense, M. lanchesteri and Halocaridina rubra） were found to be identical to the pancrustacean ground pattern; thus, it was considered that gene rear- rangements probably did not occur in the suborder Caridea. In the present study, a translocation of the trnE gene involving in- version was found in Alpheus mitochondrial genomes. This phenomenon has not been reported in any other crustacean mito- chondrial genome that has been studied so far; however, the translocation of one transfer RNA gene （trnP or trnT） was report- ed in the mitochondrial genome of Exopalaemon carinicauda. When the ratios of the nonsynonymous and synonymous sub- stitutions rates （Ka/Ks） for the 13 protein coding genes from two Alpheus species （A. japonicus and A. distinguendus） and three Macrobrachium species （M. rosenbergii, M. nipponense, M. lanchesteri） were calculated, the KaIKs values for all the protein coding genes in Alpheus and Macrobrachium mitochondrial genomes were found to be less than 1 （between 0.0048 and 0.2057）, indicating that a strong purification selection had occurred. The phylogenetic tree that was constructed based on the mitochondrial protein coding genes in the genomes of nine related species indicated that Palaemonidae and Alpheidae formed a monophyly and shared a statistically significant relationship, （Palaemonidae＋Alpheidae）＋Atyidae, at the family level.