从细胞色素b基因序列探讨笛鲷属的分子系统发生关系

测定了9种中国南海的笛鲷属鱼类的细胞色素b基因的部分序列,结合来自GenBank中1种分布于菲律宾和9种分布于美国大西洋的笛鲷属鱼类的相应同源序列,用邻接法和最大简约法构建分子系统树。结果显示:红鳍笛鲷(Lutjanuserythropterus)与红笛鲷(L.sanguineus)之间的同源序列碱基差异百分率只有0.32%,支持二者是同种异名的观点;中国南海的笛鲷属鱼类间的平均碱基差异要高于美国大西洋笛鲷属鱼类。在MP和NJ树中,美国大西洋笛鲷表现为亲缘关系较近,来源于中国南海的笛鲷鱼类相对集中在树的基部,分歧较大。这与所研究的笛鲷地理分布和地理隔离基本相一致,同时也说明中国南海笛鲷分化较早并且分歧较大。     

A new species of Enterognathus (Copepoda, Cyclopoida, Enterognathidae) collected from the Seto Inland Sea, western Japan

A new species of the endoparasitic copepod Enterognathus (Cyclopoida, Enterognathidae) is described from a crinoid host in the Seto Inland Sea, western Japan. This is a third species of the genus and its first occurrence in the Pacific Ocean. The new species is distinguished from two previously known congeners by the morphology of the body somites, caudal rami, antennae and legs. Crinoid parasites belonging to Enterognathus and the closely related genus Parenterognathus have a broad distribution from the northeastern Atlantic through the Red Sea to the West Pacific.     

Hierarchical analyses of genetic variation of samples from breeding and feeding grounds confirm the genetic partitioning of northwest Atlantic and South Atlantic populations of swordfish (Xiphias gladius L.)

In species with high migratory potential, the genetic signal revealing population differentiation is often obscured by population admixture. To our knowledge, the explicit comparison of genetic samples from known spawning and feeding areas has not been conducted for any highly migratory pelagic fish species. This study examines the geographic heterogeneity of swordfish mitochondrial DNA (mtDNA) lineages within the Atlantic Ocean using 330 base pairs of sequence of the control region from 480 individuals. Hierarchical analyses of sequence variation were conducted to test whether samples from areas identified as the corresponding spawning and feeding grounds for the northwest (NW) Atlantic (Caribbean and Georges Banks-US northeast) and the South Atlantic (Brazil-Uruguay and Gulf of Guinea), were more closely related to each other than to samples from any other region, including the Mediterranean Sea, the Indian Ocean, and the Pacific Ocean. Phylogeographic analyses reveal that swordfish mtDNA phylogeny is characterized by incomplete lineage sorting and secondary contact of two highly divergent clades. However, despite this complex phylogenetic signature, results from an analysis of nucleotide diversity and from an analysis of molecular variance (AMOVA) were for the most part concordant and indicate that NW Atlantic and South Atlantic swordfish belong to separate populations. The mtDNA distinctiveness of NW Atlantic and South Atlantic swordfish populations is indicative of philopatric behavior in swordfish towards breeding and feeding areas.     

Origin, diversification, and historical biogeography of the genus Trachurus (Perciformes: Carangidae)

We addressed phylogenetic relationships in the genus Trachurus using cytochrome b gene and D-loop sequences. The trees showed five groups: (1) the Southwest Pacific species (T. japonicus, T. novaezelandiae, and T. declivis); (2) The Mediterranean Sea and Eastern Atlantic species (T. mediterraneus); (3) The Atlantic Ocean species (T. lathami and T. trecae); (4) Eastern Atlantic species (T. trachurus and T. capensis); and (5) a group of highly mobile pelagic species, two from the Eastern Pacific (T. symmetricus and T. murphyi) and one from the Eastern Atlantic (T. picturatus). The phylogeny based on Cyt b, supports the molecular clock hypothesis and our results agree with the reported fossil indicating that the origin of this genus occur when the Thetys Sea closed (around 18.4 MYA). In addition, a very slow neutral substitution rate is reported identified only two periods of maximum diversification: the first occurring between 18.4 and 15.0 MYA and the second between 8.4 MYA and present day.     

A new look at geographic and phylogenetic relationships within the species group surrounding Octopus vulgaris (Mollusca, Cephalopoda): indications of very wide distribution from mitochondrial DNA sequences

The distribution of Octopus vulgaris has not yet been completely clarified. For a long time, a cosmopolitan distribution with unknown distribution limits had been assumed. This assumption has recently been questioned and it has been postulated that the distribution is restricted to the Mediterranean and the northeastern Atlantic. However, as our previous studies show, the existence of O. vulgaris can be confirmed for the Mediterranean and the whole eastern Atlantic, and evidence is provided for its occurrence in the western Atlantic. The aim of the present work is to extend our previous data matrix and to clarify whether O. vulgaris exists in the northwestern Pacific. Therefore, the sequence variation in ostensible O. vulgaris from 13 localities in the Mediterranean (France), the Atlantic Ocean [Lanzarote, Senegal, South Africa (Atlantic, Indian Ocean), Tristan da Cunha, north, middle and south Brazil], the Caribbean Sea (Venezuela) and the Pacific Ocean (Taiwan, Japan and Costa Rica) was examined using the mitochondrial genes coding for the 16S rRNA and cytochrome oxidase subunit III (COIII). Sequence divergence was relatively low between populations of O. vulgaris from the Mediterranean, the eastern and western Atlantic (except north Brazil), Venezuela, Taiwan and Japan compared with other species of the genus Octopus . Trees constructed by using maximum likelihood, neighbour joining and maximum parsimony algorithms (PAUP) show the above-mentioned populations from the Mediterranean, the western and eastern Atlantic, Venezuela and the northwestern Pacific (Japan and Taiwan) as a monophyletic cluster. Thus, even if the Octopus vulgaris -like octopus from north Brazil should turn out a cryptic species, the data of this work not only support our hypothesis of the distribution of O. vulgaris in the Mediterranean, the eastern and western Atlantic but also show that O. vulgaris is present in the northwestern Pacific, namely in the waters of Taiwan and Japan.     

World-wide whale worms? A new species of Osedax from the shallow north Atlantic

We describe a new species of the remarkable whalebone-eating siboglinid worm genus, Osedax, from a whale carcass in the shallow north Atlantic, west of Sweden. Previously only recorded from deep-sea (1500-3000m) whale-falls in the northeast Pacific, this is the first species of Osedax known from a shelf-depth whale-fall, and the first from the Atlantic Ocean. The new species, Osedax mucofloris sp. n. is abundant on the bones of an experimentally implanted Minke whale carcass (Balaenoptera acutorostrata) at 125m depth in the shallow North Sea. O. mucofloris can be cultured on bones maintained in aquaria. The presence of O. mucofloris in the shallow North Sea and northeast Pacific suggests global distribution on whale-falls for the Osedax clade. Molecular evidence from mitochondrial cytochrome oxidase 1 (CO1) and 18S rRNA sequences suggests that O. mucofloris has high dispersal rates, and provides support for the idea of whale-falls acting as 'stepping-stones' for the global dispersal of siboglinid annelids over ecological and evolutionary time.     

黑腹乌鲨——中国角鲨科鱼类一新纪录种

报道了采自中国南海东沙群岛外海的角鲨目鱼类1新纪录种--黑腹乌鲨Etmopterus spinax(Linnaeus, 1758).本种已有记录仅发现于东大西洋海域,本记录是大西洋东部海域以外的首次发现.乌鲨属目前在中国记录有5种,本文编制了这些种类的检索表.     

Skull morphology of bottlenose dolphins from different ocean populations with emphasis on South America

The bottlenose dolphin, genus Tursiops, is cosmopolitan occurring in tropical and temperate regions, with morphological variation between and within different oceans. Since the genus' taxonomy has been under discussion for a long time, this work aimed at analyzing the cranial variability of T. truncatus from different regions of the world. Geometric Morphometrics analyses were performed in 201 skulls of adult specimens, on dorsal, ventral, and lateral views, from the Eastern North Pacific, Eastern North Atlantic, Eastern South Atlantic, and Western South Atlantic oceans. The results indicate differences between individuals that inhabit the Atlantic and Pacific oceans. Within the Atlantic Ocean, there is an evident longitudinal differentiation of specimens from the eastern and western regions. A latitudinal separation was also observed, considering specimens from the North and South Atlantic Ocean. In the Western South Atlantic statistical differences were found between two morphological groups, identified as T. gephyreus (sensu Lahille, 1908) and T. truncatus, and the cross-validation presented 98% as minimum confidence for correct classification of these two groups. The present study provides strong morphological support to consider these two lineages as separate species.     

Thalassiosira punctigera (Castr.) comb, nov., a widely distributed marine planktonic diatom

Examination of type material showed that 8 taxa must be reduced to synonomy with Thalassiosira punctigera (Castr.) comb, nov., an extremely variable species as to size and valve structure. Preliminary experiments indicated a certain relationship between the areola size and the temperature at which clonal cultures had been grown. While previously known from the North Pacific and the South Atlantic Oceans in addition to a single record from the Caribbean Sea it has since 1979 been recorded regularly in the Skagerrak (between Denmark and Norway).     

Genetic validation of the unexpected presence of a tropical tuna,bigeye tuna (Thunnus obesus), in the Mediterranean

Bigeye tuna (Thunnus obesus, Lowe, 1839) is one of the eight recognized species of the genus Thunnus. It is considered a tropical species distributed in the Atlantic, Pacific and Indian Oceans. To date, no validated presence of this species has been reported inside the Mediterranean Sea. This study, however, confirms, for the first time, the presence of three young individuals of this species within the Mediterranean Sea.     

Panbiogeographical analysis of distribution patterns in hagfishes (Craniata: Myxinidae)

Aim To analyse the worldwide distribution patterns of hagfishes using panbiogeographical track analysis, and to attempt to correlate these patterns with the tectonic history of the ocean basins. Location Atlantic and Pacific oceans. Method The distributions of 47 out of 70 species of hagfish (in the genera Eptatretus, Myxine, Nemamyxine, Neomyxine, and Paramyxine) were studied by the panbiogeographical method of track analysis. The analysis was performed using distributional data obtained from the collections included in the Ocean Biogeographic Information System (OBIS, http://www.iobis.org ) and FishBase ( http://www.fishbase.org ), with additional records from the literature. Individual tracks were obtained for each species by plotting localities and connecting them by minimum‐spanning trees. Generalized tracks were determined from the spatial overlap between individual tracks. Results Six generalized tracks were found: in the Gulf of Mexico, Caribbean Sea, South‐eastern Atlantic, Western Pacific, North‐eastern Pacific and South‐eastern Pacific. Main conclusions The distribution patterns of myxinids are marked by a high degree of endemism and vicariance, and are correlated with the tectonic features involved in many of the events that led to the development of oceanic basins. The main massing of the group is around the Pacific Basin. In the Atlantic Ocean, the distribution of Myxine glutinosa seems to correspond to a classic trans‐oceanic track and vicariance resulting from the opening of the Atlantic Ocean during the Cretaceous. In the Pacific Ocean, the distribution of the Eptatretus and Paramyxine species is clearly associated with the margins of the Pacific tectonic plate. The generalized tracks of hagfishes are shared by several other groups of marine organisms, including many from shallow tropical waters, implying a common history for this marine biota. Overall, vicariance is a major feature of hagfish distribution, suggesting vicariant differentiation of widespread ancestors as a result of sea‐floor spreading between continents in connection with ocean formation.     

Cryptic speciation and paraphyly in the cosmopolitan bryozoan Electra pilosa--impact of the Tethys closing on species evolution

Cosmopolitan nature of the marine bryozoan Electra pilosa was studied to clarify geographic structure and to outline evolution and phylogeography of the species. Several local populations from the Northeast Atlantic (North Sea and Baltic Sea), Arctic (Barents Sea and White Sea) and Indo-West Pacific (New Zealand) were compared. In addition, we examined the closely related species E. posidoniae from the Mediterranean Sea. Phylogenetic analysis based on both 16S and 18S rDNA indicate that the Indo-West Pacific E. pilosa is a sister species to the Atlantic-Mediterranean clade, with the latter including the species E. posidoniae and the Atlantic population of E. pilosa. The topology of the phylogenetic tree leads us to conclude that E. pilosa is a paraphyletic species group relative to E. posidoniae, and a molecular dating of its divergence is consistent to geologic events associated with the closure of the Tethys Sea.     

Endemic and Indo-Pacific plankton in the Mediterranean Sea: a study based on dinoflagellate records

Aim To investigate biogeographical patterns based on published dinoflagellate records from the Mediterranean and Black Seas, and to provide a tentative list of endemic and Indo‐Pacific dinoflagellates in the Mediterranean Sea. Location Mediterranean Sea, Black Sea. Methods Checklists of dinoflagellates of the Mediterranean and Black Seas were compared with worldwide literature records. Only species reported in the Indo‐Pacific Ocean or exclusively known in the Mediterranean Sea were selected for biogeographical analysis. Results Dinoflagellates in the Mediterranean Sea comprised c. 43% of the world marine species and c. 88% of the dinoflagellate genera. Species richness among the Mediterranean sub‐basins showed marked differences due to the less reliable records of unarmoured (athecate) and rare dinoflagellates. These differences disappeared when only the more easily identifiable taxa were considered. Of the 673 dinoflagellates cited in the Mediterranean, 87% were also reported in the Atlantic Ocean. Only 40 taxa (6% of the total) were considered to be potential Indo‐Pacific species. Most were reported from the Ligurian Sea (21), and only two species from the Levantine basin. The other 48 taxa (7% of total) were known exclusively from the Mediterranean Sea, mainly from the Ligurian Sea. Half of these taxa were reported by a single author. Main conclusions Substantial dinoflagellates species richness can be attributed, in part, to the historical tradition of taxonomic studies in the Mediterranean Sea. The list of species of both Indo‐Pacific and exclusively Mediterranean species included taxa of dubious taxonomic validity or that were insufficiently known. The exclusion of these questionable taxa revealed the near absence of endemic dinoflagellates in the Mediterranean Sea compared with macroscopic organisms. This could be related to: (1) continuous replenishment of the plankton populations by the inflow of Atlantic water through the Strait of Gibraltar, (2) the possibility that species introduced during the Pliocenic flooding after the Messinian salinity crisis have not had enough time to diverge from their Atlantic ancestors, and/or (3) the reliance on traditional taxonomy based on morphological characters, which precludes the detection of cryptic speciation.     

Worldwide phylogeography of the blacktip shark (Carcharhinus limbatus) inferred from mitochondrial DNA reveals isolation of western Atlantic populations coupled with recent Pacific dispersal

Although many coastal shark species have widespread distributions, the genetic relatedness of worldwide populations has been examined for few species. The blacktip shark, (Carcharhinus limbatus), inhabits tropical and subtropical coastal waters throughout the world. In this study, we examined the genetic relationships of blacktip shark populations (n = 364 sharks) throughout the majority of the species' range using the entire mitochondrial control region (1067-1070 nucleotides). Two geographically distinct maternal lineages (western Atlantic, Gulf of Mexico, and Caribbean Sea clades, and eastern Atlantic, Indian, and Pacific Ocean clades) were identified and shallow population structure was detected throughout their geographic ranges. These findings indicate that a major population subdivision exists across the Atlantic Ocean, but not the Pacific Ocean. The historical dispersal of this widespread, coastal species may have been interrupted by the rise of the Isthmus of Panama. This scenario implies historical dispersal across the Pacific Ocean (supported by the recovery of the same common haplotype from the Philippines, Hawaii, and the Gulf of California reflecting recent/contemporary dispersal abilities) and an oceanic barrier to recent migration across the Atlantic. Genetic structure within the eastern Atlantic/Indo-Pacific (Phi(ST) = 0.612, P < 0.001) supports maternal philopatry throughout this area, expanding previous western Atlantic findings. Eastern Atlantic/Indo-Pacific C. limbatus control region haplotypes were paraphyletic to Carcharhinus tilstoni haplotypes in our maximum-parsimony analysis. The greater divergence of western Atlantic C. limbatus than C. tilstoni from eastern Atlantic/Indo-Pacific C. limbatus reflects the taxonomic uncertainty of western Atlantic C. limbatus.     

A new deep-sea hydroid (Cnidaria: Hydrozoa) from the Bering Sea Basin reveals high genetic relevance to Arctic and adjacent shallow-water species

The marine benthic fauna in Arctic shallow-water is reported to be a relatively young assemblage by species of either Pacific or Atlantic affinity. Whether current deep-sea Pacific species are included in the affinity or not is unknown. Combining morphological comparisons and genetic analyses, a new deep-sea hydroid to science, Sertularia xuelongi sp. nov. (Cnidaria: Hydrozoa: Sertulariidae), is described from the northern margin of the Bering Sea Basin at depths of 800–1570 m collected in 2010. It is characterized by slender and zigzag-shaped hydrocauli, alternately arranged hydrothecae and the absence of distal-lateral horns in fully matured female gonothecae. Its distribution, currently known only from Bering Sea Basin, suggests that it could not be an Arctic species with Pacific affinity. However, phylogenetic analyses based on the mitochondrial 16S rRNA gene show that it is clustered into a distinctive clade with four closely related species recorded from shallow-water of Northwest France, Iceland, Chukchi Sea and/or Bering Sea. In addition, its sequence similarity is highly relevant to these four species: Sertularia argentea (98.6 %), S. cupressina (98.8 %), S. plumosa (98.8 %) and S. robusta (99.4 %). All these provide a new insight into the relevance of North Pacific deep-sea species to the benthic fauna in Arctic and adjacent shallow-water. The taxonomic restriction of the genus Sertularia and the re-validation of the genus Polyserias are discussed. Future researches on more deep-sea species from Pacific and/or Atlantic are required to understand the evolution and speciation pattern involved in polar relevance.     

Population status of Greenland halibut <Emphasis Type="Italic">Reinhardtius hippoglossoides</Emphasis> (Walbaum, 1793) of the Laptev Sea

This is the first study to perform a comparative genetic analysis of Greenland halibut in the samples from the Atlantic (waters of west and east of Greenland), Arctic (Laptev Sea), and Pacific (the western part of the Bering Sea) ocean basins using seven microsatellite loci. The obtained data clearly demonstrate that the Greenland halibut population in the Laptev Sea belongs to the groups of the Atlantic Ocean basin. Apparently, the Greenland halibut of the Laptev Sea is represented by a dependent population, which is replenished due to the drift of immatures from the spawning grounds in the Barents Sea with the transformed Atlantic water flow along the continental slope. In addition, the Arctic population can be partially replenished due to the breeding of the halibut in local spawning grounds.     

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

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

Population biology of the myctophid fish Gymnoscopelus nicholsi (Gillbert, 1911) from the western South Atlantic

Thirty-three collections of Gymnoscopelus nicholsi were made between 1976 and 1981 in the South Atlantic using both krill and bottom trawls. In the Antarctic waters the main part of the stock consisted of adult fish 3–7 years old, characterized by a benthopelagic mode of life. Fish of year-class I were observed only in the vicinity of South Georgia, South Sandwich Islands and the Scotia Sea; year-class II individuals were absent from Antarctic samples. In the notal zone of the western South Atlantic, fish aged 1–5 years were found. The existence of only one population in the region is a possible explanation of these findings: this population is divided into a pelagic stock of juveniles and sub-adults which occur in the offshore waters of the western South Atlantic and benthopelagic stocks of adults distributed over the slope regions off Argentina, South Georgia and Antarctic archipelagos.
The computed values of K (von Bertalanffy growth) were 0.48, 0.41 and estimated total annual instantaneous mortality rates (Z) were 0.45, 0.67, and 0.70 for South Georgia, South Shetlands and notal zone of western South Atlantic stocks, respectively.     

Natal origin of Namibian grey whale implies new distance record for in-water migration

We use genomics to identify the natal origin of a grey whale found in the South Atlantic, at least 20 000 km from the species core range (halfway around the world). The data indicate an origin in the North Pacific, possibly from the endangered western North Pacific population, thought to include only approximately 200 individuals. This contributes to our understanding of Atlantic sightings of this species known primarily from the North Pacific, and could have conservation implications if grey whales have the potential for essentially global dispersion. More broadly, documenting and understanding rare extreme migration events have potential implications for the understanding of how a species may be able to respond to global change.