Genealogical relationships within and among shallow-water <Emphasis Type="Italic">Ciona</Emphasis> species (Ascidiacea)

In spite of historical and current interest in Ciona intestinalis and its congeners, little is known about evolutionary relationships among the members of the genus Ciona. Here 744-bp sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene are used to examine phylogenetic relationships among three described species (C. intestinalis, C. roulei, C. savignyi) sampled from multiple coastal sites in the Northeast Pacific (CA, USA), Northwest Atlantic (from New Hampshire to Connecticut, USA), Northeast Atlantic (Sweden and The Netherlands), and Mediterranean (Banyuls-sur-Mer, France). The samples were collected in June–October 2005. The COI sequences of Northeast Pacific/Mediterranean (Type A) and Northwest Atlantic (Type B) C. intestinalis differ by ∼12% and C. roulei is nested within Type B C. intestinalis. Ciona savignyi differs from all other haplotypes by 13–16%. A previously undescribed but morphologically distinct Ciona sp. found at the Banyuls-sur-Mer site was >10% divergent from all other haplotypes. Although these data arise from a single gene study, they indicate that further elucidation of species relationships within the genus and of the species’ distributions will be needed if continuing invasions and potential reproductive isolation are to be investigated.     

Genetic evidence for two distinct clades in a French Polynesian population of the coral reef three-spot damselfish<Emphasis Type="Italic"> Dascyllus trimaculatus</Emphasis>

Previous studies have shown that the three-spot damselfish species complex [ Dascyllus albisella Gill, D. auripinnis Randall and Randall, D. strasburgi Klausewitz, D. trimaculatus (Ruppell)] is an assemblage of five geographically distinct clades. The one exception was a single D. trimaculatus from French Polynesia, which grouped with "Pacific Rim" individuals. In the present study, an additional 252 individuals from French Polynesia collected between June 1996 and January 2002 were analyzed using PCR amplifications, restriction fragment length polymorphisms, and DNA sequencing of the mitochondrial control region. The French Polynesian D. trimaculatus belong to two distinct clades. One clade comprising 96% of the individuals includes haplotypes found only in French Polynesia. The other clade (4% of the individuals) is comprised of haplotypes that cluster with "Pacific Rim" individuals, a clade with widespread distribution from Japan to the Line Islands and from Wallis to Palau. Present data suggest that a small number of larvae from northwestern reefs (possibly Line Islands) may have occasionally reached and colonized French Polynesian reefs.     

Phylogeography of the ocean quahog (Arctica islandica): influences of paleoclimate on genetic diversity and species range

The ocean quahog, Arctica islandica (Linnaeus, 1767), is a commercially important bivalve found on continental shelves throughout much of the North Atlantic. To assess genetic subdivision in this species, we sequenced 385 nucleotides of the mitochondrial cytochrome b (cyt b) gene from 83 specimens collected from 12 localities between September 1998 and July 1999 (based on preliminary data, the Internal Transcribed Spacers, ITS, of the nuclear ribosomal repeat were not useful). The cyt b data delimited 11 haplotypes with 0.26 to 8.1% nucleotide difference (coded by 36 variable nucleotide positions) among them. Only three haplotypes were detected in 39 specimens collected along the USA coastline, compared to five haplotypes from nine Icelandic individuals. The western Atlantic populations ranging from Penobscot Bay (Maine, USA) to southern Virginia showed relatively low diversity and appeared genetically similar in that region. Based on the presence of shared haplotypes, AMOVA analyses, and phylogenetic reconstructions, Icelandic populations appear to be more genetically similar to western Atlantic populations than eastern Atlantic populations. Specimens from the Faroe Islands (n=4) show mixed affinities. These data are consistent with the hypothesis that a warm Holocene climatic optimum (ca. 7,500 years BP), and not glacial refugia, shaped the present-day genetic structure in A. islandica. Received: 18 January 2000 / Accepted: 26 June 2000     

Paralytic shellfish poisoning due to Pyrodinium bahamense var. compressa in Mati,Davao Oriental,Philippines

On 26 August 1983, a single case of paralytic shellfish-poisoning (PSP) was reported in Davao City, Philippines. The poisoning was traced to ingestion of the green mussel Perna viridis Linnaeus, gathered from Balete Bay, Mati, Davao Oriental. Phytoplankton and zooplankton analyses on 12 October 1983 (47 d later), revealed the presence of the dinoflagellate Pyrodinium bahamense var. compressa, a cause of a series of red tides in the early and middle 1970's in Papua New Guinea, Sabah, and Brunei, and more recently, in Palau, and Western Samar and Leyte, Philippines. The dinoflagellate was not dominant; in fact the enumeration showed greater numbers of Ceratium sp., another dinoflagellate. Quantification of the neurotoxin by the standard mouse assay revealed a very high potency. Mussels collected from a new raft (transplanted in May 1983) had a toxicity of 7 960 mouse units (MU) per 100 g^-1 meat. Those from an old raft (transplanted in May 1982) had a toxicity of 9 620 MU per 100 g^-1 meat.SEAFDEC Contribution No. 145     

New insights on population genetic structure of <Emphasis Type="Italic">Delphinus delphis</Emphasis> from the northeast Atlantic and phylogenetic relationships within the genus inferred from two mitochondrial markers

The taxonomic status of common dolphins (Delphinus sp.) remains controversial despite the increased number of studies focusing on its populations. Two species are presently recognized, Delphinus delphis and D. capensis. Apart from a phylogeographic study of the genus Delphinus, genetic studies focusing specifically in the northeast (NE) Atlantic remain scarce. Following ecological and morphological evidence for the existence of different common dolphin morphotypes in the Portuguese coast, we examined the population structure of D. delphis from the NE Atlantic by comparing DNA sequences from two mitochondrial regions (control region and cytochrome b gene). Additionally, we compared the sequences obtained with existing sequences of D. delphis from the Azores, Black Sea, Canary Islands, Pacific Ocean, D. capensis and also two closely related delphinid species (Stenella coeruleoalba and Tursiops truncatus). In the analysis of the NE Atlantic populations, we found evidence for the existence of some level of genetic differentiation. In the broader phylogenetic analysis, D. delphis and D. capensis did not show reciprocal monophyly and we found a group of highly divergent individuals. We discuss the possibility for the existence of two divergent lineages that have evolved independently, a separate subspecies or events of introgressive hybridization. These findings could have important implications on a taxonomic level, although further investigation based on a larger geographical scale and on nuclear loci information will certainly elucidate the origin of these highly divergent individuals.     

Phylogeography of the calanoid copepods <Emphasis Type="Italic">Calanus helgolandicus</Emphasis> and <Emphasis Type="Italic">C. euxinus</Emphasis> suggests Pleistocene divergences between Atlantic,Mediterranean, and Black Sea populations

Molecular systematic analyses of marine taxa are crucial for recording ocean biodiversity, so too are elucidation of the history of population divergence and the dynamics of speciation. In this paper we present the joined phylogeography of the calanoid copepod Calanus helgolandicus (Claus 1863) from the North East (NE) Atlantic and the Adriatic Sea and the closely related C. euxinus (Hulsemann 1991) from the Black Sea based on sequences of a mitochondrial Cytochrome Oxidase subunit I (COI) fragment. Coalescent-based Bayesian methods and minimum spanning networks are used to reconstruct the history of population divergence. Our results reveal that copepod populations from all three basins share a great number of haplotypes and demonstrate a close genetic affinity of C. euxinus with C. helgolandicus. The data do not support significant genetic structuring among samples within seas. Coalescent analyses suggest divergences between NE Atlantic, Mediterranean, and Black Sea populations dating back to the middle Pleistocene, with the NE Atlantic–Mediterranean divergence being the earliest and the Mediterranean–Black Sea divergence the most recent. These middle Pleistocene dates are much older than the estimated dates of colonisation of the Mediterranean and Black Seas based on paleoclimatic scenarios. Our results do not rule out that the assumed colonisations took place but they indicate that the populations colonising the Mediterranean and the Black Sea were already, and have since remained, diverged. The chaetognath Sagitta setosa, which has a comparable distribution pattern and feeds upon the copepods, provides a unique opportunity to compare phylogeographic patterns and distinguish among alternative hypotheses. The dates produced in this paper are in agreement with those estimated elsewhere for S. setosa. We propose that a great deal of the genetic make-up of marine planktonic populations comprises divergences that date back to long before the last glacial maximum. We consider questions on the taxonomic status of C. euxinus to remain open. However, its high genetic affinity to the C. helgolandicus calls for further investigation.     

Inter-ocean genetic divergence of istiophorid billfishes

Restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA) was used to investigate the taxonomic status of the following species-pairs of Atlantic and Indo-Pacific istiophorid billfishes: Atlantic blue marlin Makaira nigricans (Lacépède) and Indo-Pacific blue marlin M. mazara (Jordan and Snyder); Atlantic sailfish Istiophorus albicans (Latreille) and Indo-Pacific sailfish I. platypterus (Shaw and Nodder); and white marlin Tetrapturus albidus Poey and striped marlin T. audax (Phillippi). Tissue samples were collected from 1990 to 1992. Several mtDNA haplotypes were common to Atlantic and Indo-Pacific samples of blue marlin and sailfish, although there were significant differences in the distribution of haplotypes between samples from different oceans. For both blue marlin and sailfish, a single group of closely related mtDNA haplotypes was found among all indo-Pacific and some Atlantic individuals, while the remaining Atlantic specimens exhibited mtDNA haplotypes that differed by several consistent restriction site changes from the common haplotype. No restriction site differences were found to discriminate white marlin from striped marlin, and the mtDNA haplotypes of both species were very similar although significant differences were found in the distribution of haplotypes between the two species. Two of 26 haplotypes were shared between white and striped marlin, and the corrected mean nucleotide sequence divergence between species (0.06%) was not much greater than that observed between geographically distant samples of striped marlin from the Pacific Ocean (mean 0.03%). The presence of identical haplotypes in samples from both oceans for each of the three species-pairs of istiophorid billfishes suggests that specific status may not be warranted for any of the Atlantic and Indo-Pacific populations. The significant difference in the distributions of mtDNA haplotypes between Atlantic and Indo-Pacific populations, which contrasts sharply with the homogeneity reported for several species of tunas, indicates considerable population structuring within the highly vagile billfishes.     

Spatial–temporal pattern of bluefin tuna (Thunnus thynnus L. 1758) gonad maturation across the Mediterranean Sea

Atlantic bluefin tuna (BFT; Thunnus thynnus) is a migrating species straddling the North Atlantic Ocean and Mediterranean Sea. It is assumed that this species is divided into a western and an eastern stock, which spawn in the Gulf of Mexico and the Mediterranean Sea, respectively. To learn more about the reproductive behavior of the eastern BFT stock, we tracked gonadal development in adult fish that were sampled between April and July during three consecutive years (2003–2005). Sampling campaigns were carried out using common fishing methods at selected locations within the Mediterranean Sea, namely Levantine Sea, Malta, and Balearic Islands. An additional sampling point, Barbate, was situated northwest of the Straits of Gibraltar along the Atlantic coast. Morphometric parameters such as the total body mass (M _B) and the weights of the gonads (M _G) were recorded, and the respective gonadosomatic index (GSI) values were calculated. The data collected revealed two important trends: (1) GSI values are higher in fish caught in the eastern rather than the western locations across the Mediterranean Sea, and (2) the GSI reaches maximum values between late May and early June in Levantine Sea (eastern Mediterranean Sea), and only 2 and 4 weeks later in the central (Malta) and western (Balearic Islands) locations, respectively. The advanced gonadal development in BFT correlates well with higher sea surface temperatures. Our findings also distinguish the northern Levantine Sea BFT population (mean M _B 78.41 ± 4.13 kg), and the Barbate BFT population with the greatest M _B (all fish sampled > 100 kg). These data reflect a situation in which the eastern Mediterranean basin may function as a habitat for young BFT, until they gain a larger M _B and are able to move to the Atlantic Ocean. However, the existence of genetically discrete BFT populations in the Mediterranean Sea cannot be ruled out.     

Evolution of coral reef fish<Emphasis Type="Italic"> Thalassoma</Emphasis> spp. (Labridae). 2. Evolution of the eastern Atlantic species

The genetic relationships within and among congeneric species of marine fish from the Atlantic and the Mediterranean are poorly known. Relationships among all five species of the wrasse genus Thalassoma present in the Atlantic and the Mediterranean were examined using sequence data from the mitochondrial control region. Sampling was focused on the mid-Atlantic T. sanctaehelenae (Valenciennes, 1839) and T. ascensionis (Quoy & Gaimard, 1834), the eastern Atlantic T. newtoni (Osório, 1891) from Sao Tome, and the eastern Atlantic/Mediterranean T. pavo (Linnaeus, 1758). Two western Atlantic species T. bifasciatum (Bloch, 1791) from the Caribbean and T. noronhanum (Boulenger, 1890) from Brazil served as outgroups. Tissues from a total of 132 individuals were sequenced. T. newtoni from Sao Tome preferentially grouped with the central Atlantic T. sanctaehelenae and T. ascensionis. T. pavo exhibits two distinct coloration patterns, one in the Cape Verde Islands and one in the eastern Atlantic Islands and Mediterranean. However, no genetic discontinuities between the Cape Verde Islands and the remaining samples or between Atlantic and Mediterranean individuals were found. Within Mediterranean populations of T. pavo, our data suggested the presence of a genetic break between eastern and western regions.Communicated by J.P. Grassle, New Brunswick     

Atlantic-Mediterranean and within-Mediterranean molecular variation in <Emphasis Type="Italic">Coris julis</Emphasis> (L. 1758) (Teleostei,Labridae)

Sequence variation in the mitochondrial control region was studied in the Mediterranean rainbow wrasse (Coris julis), a species with pronounced pelagic larval phase inhabiting the Mediterranean Sea and the adjacent coastal eastern Atlantic Ocean. A total of 309 specimens from 19 sampling sites were analysed with the aim of elucidating patterns of molecular variation between the Atlantic and the Mediterranean as well as within the Mediterranean Sea. Phylogeographic analyses revealed a pronounced structuring into a Mediterranean and an Atlantic group. Samples from a site at the Moroccan Mediterranean coast in the Alboran Sea showed intermediate frequencies of “Mediterranean” and “Atlantic” haplotypes. We recognised a departure from molecular neutrality and a star-like genealogy for samples from the Mediterranean Sea, which we propose to have happened due to a recent demographic expansion. The results are discussed in the light of previous studies on molecular variation in fish species between the Atlantic and the Mediterranean and within the Mediterranean.     

Genetic analysis of tuna populations,<Emphasis Type="Italic"> Thunnus thynnus thynnus</Emphasis> and<Emphasis Type="Italic"> T</Emphasis>.<Emphasis Type="Italic"> alalunga</Emphasis>

The genetic population structures of Atlantic northern bluefin tuna ( Thunnus thynnus thynnus) and albacore ( T. alalunga) were examined using allozyme analysis. A total of 822 Atlantic northern bluefin tuna from 18 different samples (16 Mediterranean, 1 East Atlantic, 1 West Atlantic) and 188 albacore from 5 samples (4 Mediterranean, 1 East Atlantic) were surveyed for genetic variation in 37 loci. Polymorphism and heterozygosity reveal a moderate level of genetic variability, with only two highly polymorphic loci in both Atlantic northern bluefin tuna ( FH* and SOD- 1*) and albacore ( GPI- 3* and XDH*). The level of population differentiation found for Atlantic northern bluefin tuna and albacore fits the pattern that has generally been observed in tunas, with genetic differences on a broad rather than a more local scale. For Atlantic northern bluefin tuna, no spatial or temporal genetic heterogeneity was observed within the Mediterranean Sea or between the East Atlantic and Mediterranean, indicating the existence of a single genetic grouping on the eastern side of the Atlantic Ocean. Very limited genetic differentiation was found between West Atlantic and East Atlantic/Mediterranean northern bluefin tuna, mainly due to an inversion of SOD- 1* allele frequencies. Regarding albacore, no genetic heterogeneity was observed within the Mediterranean Sea or between Mediterranean and Azores samples, suggesting the existence of a single gene pool in this area.     

Daily photosynthesis,respiration, and carbon budgets in a tropical marine jellyfish (Mastigias sp.)

From measured diel photosynthesis and respiration rates, using oxygen electrodes, estimates of carbon flux between symbiotic algae (zooxanthellae) and host animal are presented for the marine scyphomedusan Mastigias sp. from a marine lake in Palau, Western Caroline Islands, during February and March 1982. The carbon budgets calculated for these lake medusae indicate that carbon fixed photosynthetically by zooxanthellae and made available to the host may satisfy up to 100% of the host's daily metabolic carbon demand (CZAR). The stable carbon isotope (¹³C) signature of the mesogleal carbon of lake Mastigias sp. was close to that of the zooxanthellae, supporting the interpretation that while these medusae may feed holozoically, some of their carbon comes from their symbionts. The diel photosynthesis, respiration, and preliminary estimates of carbon budgets of three individuals of another ecotype of Mastigias sp. collected from nearby oceanic lagoons are also given. Photosynthesis of lagoon medusae was generally greater than that for lake medusae of similar size, and lagoon medusae were phototrophic with respect to carbon, with commensurately greater CZAR values. Carbon translocated from the symbiotic algae also may contribute to the growth requirements of both lake and lagoon medusae. From carbon flux data, the lake jellyfish were estimated to contribute about 16% to the total primary productivity of their marine lake habitat.     

Population structure and historical demography of the thorny skate (<Emphasis Type="Italic">Amblyraja radiata</Emphasis>, Rajidae) in the North Atlantic

Population genetic structure of the thorny skate (Amblyraja radiata) was surveyed in >300 individuals sampled from Newfoundland, Iceland, Norway, the Kattegat and the central North Sea. A 290-bp fragment of the mt cytochrome-b gene was first screened by SSCP. Sequences of SSCP haplotypes revealed 34 haplotypes, 14 of which were unique to Iceland, 3 to Newfoundland, 1 to Norway and 3 to the Kattegat. The global F _ST was weak but significant. Removal of the two Kattegat locations, which were the most differentiated, resulted in no significant genetic differentiation. Haplotype diversity was high and evenly distributed across the entire Atlantic (h = 0.8) with the exception of the North Sea (h = 0.48). Statistical parsimony revealed a star-like genealogy with a central widespread haplotype. A subsequent nested clade analysis led to the inference of contiguous expansion with evidence for long distance dispersal between Newfoundland and Iceland. Historical demographic analysis showed that thorny skates have undergone exponential population expansion that started between 1.1 million and 690,000 years ago; and that the Last Glacial Maximum apparently had little effect. These results strongly differ from those of a parallel study of the thornback ray (Raja clavata) in which clear structure and former refugial areas could be identified. Although both species have similar life history traits and overlapping ranges, the continental shelf edge apparently does not present a barrier to migration in A. radiata, as it does for R. clavata.     

Mitochondrial DNA lineages in the European populations of mussels (<Emphasis Type="Italic">Mytilus</Emphasis> spp.)

Marine mussels (Mytilus spp.) belong to a group of benthic species crucial to coastal ecosystems in Europe and are important for the cultivation industry. In the present study, the nuclear adhesive protein marker (Me15/16) was used for identification of Mytilus species in coastal areas, on a large geographic scale in Europe. Pure M. edulis populations were found in the White Sea and Iceland. M. edulis, M. trossulus and their hybrids were found in the Baltic Sea and the North Sea (Oosterschelde, The Netherlands). M. galloprovincialis, M. edulis and their hybrids occurred in Ireland. M. galloprovincialis populations were observed in the Sea of Azov (Black Sea), the Mediterranean and Portugal. The mitochondrial (mt) DNA coding-region ND2-COIII was studied by PCR (polymerase chain reaction) and RFLP (restriction fragment length polymorphism) assay methods. The mtDNA control region was studied by PCR. Substantial differentiation in the frequency of female haplotypes among the studied populations in Europe was observed. Despite isolation between the Mytilus taxa on a macro-geographic scale, considerable mitochondrial gene flow occurred between populations, with introgression in hybrid zones on a more local geographic scale in Europe. MtDNA of the Atlantic Iberian (Portugal) population of M. galloprovincialis was more similar to mtDNA in populations of M. galloprovincialis and M. edulis from the Atlantic coasts of the Ireland and M. edulis from the North Sea, than to M. galloprovincialis from the Mediterranean. Lower polymorphism of mtDNA in populations of the Baltic and Azov Sea mussels in comparison with other European populations was observed and can be explained by the recent history of both seas after the Pleistocene glaciation. In the M. galloprovincialis population from the Azov Sea, the presence of the male-inherited (M) genome was demonstrated for the first time by sequencing the control region and was observed at high frequency. Possible influence of mussel culture on geographic distribution of the Mytilus taxa in Europe is discussed.     

Mitochondrial DNA variation in the European lobster (<Emphasis Type="Italic">Homarus gammarus</Emphasis>) throughout the range

The genetic differentiation of the European lobster (Homarus gammarus) was investigated in 3,283 individuals from 44 population samples throughout its geographical distribution (Norway to Greece) by means of polymerase chain reaction restriction fragment length polymorphism analysis of a 3-kb mitochondrial DNA segment. Ninety composite haplotypes were revealed with the number of haplotypes in each population sample ranging from 4 to 31. Private haplotypes were found at very low frequencies. The global exact test of sample differentiation based on composite haplotype frequencies was statistically significant. F_ST analyses also showed significant heterogeneity among the European lobster population samples (F_ST=0.078, P<0.001). This differentiation was mainly due to the population samples from northern Norway, the Netherlands, and the Mediterranean Sea. These samples differentiated from the rest due to reduced gene diversity rather than to unique haplotypes. The relationships among these samples were illustrated with cluster analyses; four major distinct groups were evident: Mediterranean, northern Norway, Netherlands, and the remaining Atlantic samples. Based on the low degree of differentiation revealed in the European lobster and its limited capacity for dispersal, the most probable hypothesis is that all populations have been established from a common refuge after the end of the last Ice Age, that is, within the past 15,000 years. The results of this study show that mitochondrial DNA is a powerful tool for the determination of the genetic structure among lobster samples, which is important for a proper management policy designed to protect and to cultivate this species.Communicated by O. Kinne, Oldendorf/Luhe     

Phylogeny and geographic differentiation of Atlanto–Mediterranean species of the genus Xantho (Crustacea: Brachyura: Xanthidae) based on genetic and morphometric analyses

The crab genus Xantho Leach, 1814 is restricted to the northeastern Atlantic Ocean and the Mediterranean Sea. It consists of four species, Xantho hydrophilus (Herbst, 1790), X. poressa (Olivi, 1792), X. pilipes A. Milne-Edwards, 1867, and X. sexdentatus (Miers, 1881). X. hydrophilus has been divided into two geographic forms, of which one, X. h. granulicarpus (Forest, 1953), is postulated to be endemic to the Mediterranean Sea. In this study, we reconstruct phylogenetic relationships of the genus Xantho and related genera from the Atlantic Ocean or Mediterranean Sea and compare different geographic populations of Xantho hydrophilus and, to a lesser extent, of X. poressa by means of population genetic and morphometric analyses. The molecular phylogeny is based on two mitochondrial genes (large subunit rRNA and cytochrome oxidase I) and indicates that X. poressa, X. hydrophilus and X. sexdentatus form a monophyletic group, the latter two species sharing identical haplotypes. On the other hand, X. pilipes shows affinities to Xanthodius denticulatus. Population genetics based on the COI gene reveal genetic differentiation within X. hydrophilus. Morphometric results also give evidence for distinct geographic forms in X. hydrophilus with a clear discrimination. In comparison, morphometric discrimination between different geographic populations of X. poressa is less clear, but still significant. We therefore suggest a recent/ongoing morphological and genetic differentiation within Xantho hydrophilus, restricted gene flow between its Atlantic and Mediterranean populations (not allowing subspecific differentiation) and possible mtDNA introgression between the species X. hydrophilus and X. sexdentatus.     

Phylogenetic relationships among species of Calyptogena (Bivalvia: Vesicomyidae) collected around Japan revealed by nucleotide sequences of mitochondrial genes

Phylogenetic relationships among the seven species of deep-sea giant clams Calyptogena (Bivalvia: Vesicomyidae) collected around Japan were examined using parts of nucleotide sequences of mitochondrial genes for cytochrome oxidase I (COI) and cytochrome oxidase III (COIII) and the encoded amino acid sequences. The seven species were C. soyoae (Sagami Bay), C. fausta (Suruga Bay), C. kaikoi (Nankai Trough), C. nautilei (Nankai Trough), C. phaseoliformis (Japan Trench), C. solidissima (Minami-Ensei Knoll, Okinawa Trough) and Calyptogena sp. (Iheya Ridge, Okinawa Trough). A clear phylogenetic split was observed between one group of three species (C. kaikoi, C. phaseoliformis and C. fausta) and the remaining species. This clustering corresponds to the two previously described subgenera within the genus Calyptogena (Calyptogean and Ectenagena) with the exception of the placement of C. nautilei, which had been placed in the subgenus Ectenagena. Genetic distances between two haplotypes of C. soyoae were 0.043 for the COI region and 0.055 for the COIII region, and three amino acid substitutions were detected with the COIII region. Calyptogena sp. from the Iheya Ridge could be distinguished from one of the two haplotypes (type A) of C. soyoae by only a single nucleotide substitution, a result that suggests that Calyptogena sp. of the Iheya Ridge diverged from C. soyoae after the two haplotypes had diverged, and it is now isolated from C. soyoae in Sagami Bay.     

Regional patterns of microsatellite variation in <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> from the Iberian Peninsula

The Almería-Oran Oceanographic Front (AOOF) has been proposed as an effective marine barrier to gene flow between the NE Atlantic Ocean and the Mediterranean Sea for several species. Previous studies using allozymes and mitochondrial DNA have reported a scenario of secondary intergradation between populations of Mytilus galloprovincialis from those basins, with the allelic frequencies of some loci showing abrupt clinal patterns across the AOOF. In this study, we aimed at testing the congruence between six neutral polymorphic microsatellites versus previous data on allozymes and mtDNA-RFLPs, at depicting the population structure of this species in the Iberian Peninsula. Microsatellite genotyping was scored on 17 samples of mussels collected in the Iberian coast, including some areas not sampled before. Microsatellites exhibited larger intrabasin diversity (F _SC = 1.72%, ), similar interbasin differentiation (F _CT = 2.81%) and fewer allelic clines than allozymes or mtDNA haplotypes. These results fully support the scenario of secondary intergradation with some ongoing gene flow between basins, as proposed in previous analyses. Moreover, this congruence between markers and analyses separated by a 12-year period (1988–2000) confirm the temporal stability of this marine barrier at shaping the Iberian phylogeographic break in M. galloprovincialis. In addition, the genetic continuity between the NE Atlantic (Portugal) and the Alboran Sea seems to be warranted across the Gulf of Cadiz and the Gibraltar strait after the present microsatellite data. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Variability of albacore (<Emphasis Type="Italic">Thunnus alalunga</Emphasis>) diet in the Northeast Atlantic and Mediterranean Sea

This study aims to describe the variability of albacore (Thunnus alalunga) diet in the Northeast Atlantic and Mediterranean Sea and to identify possible relationships between this variability and the features of different feeding areas, the behavior, and the energetic needs of albacore. Stomach contents from albacore caught in five zones of the Bay of Biscay and surrounding waters (n = 654) and three zones of the Mediterranean Sea (n = 152) were analyzed in terms of diet composition and stomach fullness. Carbon and nitrogen stable isotope and C/N ratios were measured for white muscle and liver from albacore in the Bay of Biscay (n = 41) and Mediterranean Sea (n = 60). Our results showed a spatial, seasonal, inter-annual, and size-related variability in the diet of albacore. Albacore diet varied by location in the Mediterranean Sea, with a particularly high proportion of cephalopods, and low δ¹⁵N values in the Tyrrhenian Sea. In the Northeast Atlantic, albacore consumed a higher proportion of crustaceans and a lower proportion of fishes in the most offshore sampling zone than inshore. The digestion states of the major prey reflected a diurnal feeding activity, indicative of feeding in deeper waters offshore, whereas on the continental slope, feeding probably occurred in surface waters at night. Important seasonal and inter-annual diet variability was observed in the southeast of the Bay of Biscay, where preferred albacore prey appeared to be anchovy (Engraulis encrasicolus). Stomach fullness was inversely related to body size, probably reflecting higher energetic needs for smaller individuals. Albacore from the Bay of Biscay had significantly lower δ¹³C and higher δ¹⁵N values compared with albacore from the Mediterranean Sea, indicative of regional baseline shifts, and trophic position and muscle lipid stores in albacore increased with body size.     

Phylogeographic differentiation of storm petrels (<Emphasis Type="Italic">Hydrobates pelagicus</Emphasis>) based on cytochrome<Emphasis Type="Italic"> b</Emphasis> mitochondrial DNA variation

We evaluated mitochondrial DNA (mtDNA) sequence variation in a 910 bp region of the cytochrome b gene of the storm petrel, Hydrobates pelagicus. Samples from birds collected from five populations in the North Atlantic Ocean and the Mediterranean Sea were investigated. Genetic differentiation within the Mediterranean basin was low but high in the Atlantic. Strong differences were noted between the Atlantic and the Mediterranean populations, confirming the distinction of the subspecies H. p. pelagicus and H. p. melitensis for the Atlantic and Mediterranean seabirds, respectively. Divergence between the two subspecies probably resulted from paleogeographic changes in the Strait of Gibraltar, which was likely the route used by H. pelagicus to invade the Mediterranean Sea. Current and past demography and ecology of the storm petrel is regarded as an explanation for the level of differentiation observed within each oceanic basin. We compare the phylogeographic pattern of the storm petrel to other seabirds that breed in the same regions.Communicated by S. A. Poulet, RoscoffC.C. and L.B. contributed equally to this paper.