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1.
Benthic marine invertebrates with long-lived larvae are believed to have dispersal capabilities that contribute to maintaining
genetic uniformity among populations over large geographical scales. However, both hydrological and biological factors may
limit the actual dispersal of such larvae. We studied the population genetic structure of the edible common sea urchin Paracentrotus lividus (Lamarck, 1816), to explore its dispersal patterns in the Atlanto-Mediterranean region and, more specifically, to ascertain
the role of the Strait of Gibraltar in shaping the genetic structure of this species. For this purpose, we analysed 158 individuals
for the mitochondrial 16S rRNA gene and 151 of these for the nuclear single-copy intron adenine nucleotide transporter (ANT)
from 16 localities from the Atlantic and Mediterranean basins, spanning over 4,000 km. Mitochondrial 16S rRNA shows higher
genetic diversity in the Mediterranean than in the Atlantic and reveals a sharp break between the populations of both basins,
probably as a consequence of the barrier imposed by the Almería–Orán hydrological front, situated east of the Strait of Gibraltar.
Both markers suggest that a recent population expansion has taken place in both basins, most probably following the Messinian
salinity crisis.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
2.
Spatial and temporal population genetic structures of the common sole, Solea solea, were studied in Northeastern Atlantic and Mediterranean Sea populations, using three polymorphic exon-primed intron-crossing
(EPIC) markers. Results demonstrated significant multilocus differentiation among Eastern Mediterranean and a group composed
by Western Mediterranean and Atlantic populations (θ = 0.150, P < 0.001), but also suggested unrecorded genetic differentiation of the Adriatic Sea population. No pattern of isolation-by-distance
was recorded across the range covered by sampling, from the Kattegat to the Aegean Sea. Conversely to genetically structured
Mediterranean populations, Atlantic populations ranging from Denmark to Portugal could be considered as representative of
the same panmictic unit (θ = 0.009, not significant). Results further demonstrated stability of multilocus genetic structure among temporarily replicated
cohort samples [0+, 1+, subadults] from several coastal and estuarine locations from Bay of Biscay, excepted for the amylase
locus Am2B3-2 at one location (Pertuis d’Antioche). Despite coherence of such observed patterns of multilocus differentiation with previous
allozymic surveys in sole, and with patterns generally obtained for other marine fish species, single-locus results from EPICs
indicated divergent coalescence schemes supporting a complex response to ecology and history of sole’s populations. Results
stress the use of nuclear genes such as EPIC markers to investigate population structure, but also historical, demographic,
and possibly selective processes in marine fishes. 相似文献
3.
Pelagic dispersal of larvae in sessile marine invertebrates could in principle lead to a homogeneous gene pool over vast distances,
yet there is increasing evidence of surprisingly high levels of genetic differentiation on small spatial scale. To evaluate
whether larval dispersal is spatially limited and correlated with distance, we conducted a study on the widely distributed,
viviparous reef coral Seriatopora hystrix from the Red Sea where we investigated ten populations separated between ~0.150 km and ~610 km. We addressed these questions
with newly developed, highly variable microsatellite markers. We detected moderate genetic differentiation among populations
based on both F
ST and R
ST (0.089 vs. 0.136, respectively) as well as considerable heterozygote deficits. Mantel tests revealed isolation by distance
effects on a small geographic scale (≤20 km), indicating limited dispersal of larvae. Our data did not reveal any evidence
against strictly sexual reproduction among the studied populations. 相似文献
4.
Spatial and temporal genetic homogeneity in the Arctic surfclam (<Emphasis Type="Italic">Mactromeris polynyma</Emphasis>) 总被引:1,自引:0,他引:1
Commercially harvested marine bivalve populations show a broad range of population-genetic patterns that may be driven by
planktonic larval dispersal (gene flow) or by historical (genetic drift) and ecological processes (selection). We characterized
microsatellite genetic variation among populations and year classes of the commercially harvested Arctic surfclam, Mactromeris polynyma, in order to test the relative significance of gene flow and drift on three spatial scales: within commercially harvested
populations in the northwest Atlantic; among Atlantic populations; and between the Atlantic and Pacific oceans. We found small
nonsignificant genetic subdivision among eight populations from the northwest Atlantic (F
ST = 0.002). All of these Atlantic populations were highly significantly differentiated from a northeast Pacific population
(F
ST = 0.087); all populations showed high inbreeding coefficients (F
IS = 0.432). We tested one likely source of heterozygote deficits by aging individual clams and exploring genetic variation
among age classes within populations (a temporal Wahlund effect). Populations showed strikingly different patterns of age
structure, but we found little differentiation among age classes. In one case, we were able to analyze genetic diversity between
age classes older or younger than the advent of intensive commercial harvesting. The results generally suggest spatially broad
and temporally persistent genetic homogeneity of these bivalves. We discuss the implications of the results for the biology
and management of surfclam populations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
5.
Northern and Spotted Wolffishes (Anarhichas denticulatus and A. minor) are demersal marine fishes listed as “threatened” in Canadian waters. Both species have unusually large benthic eggs and
large size at hatch, which should reduce passive dispersal. We examined population differentiation with microsatellite and
AFLP loci across the ranges of both species in the North Atlantic Ocean. Although significant population structure was documented,
differentiation was less than expected based on knowledge of life history characteristics. Significant differentiation was
found in Northern Wolffish between the Barents Sea and other samples based on both microsatellite and AFLP data. In contrast,
population structure in the Spotted Wolffish was notably weaker, particularly with microsatellites. Both species were characterized
by low genetic diversity for marine fishes and had significantly lower genetic diversity than the congeneric Atlantic Wolffish.
This finding was consistent with the conservation status of these three species and suggests potential vulnerability to over-exploitation
in Northern and Spotted Wolffishes. 相似文献
6.
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. 相似文献
7.
Genetic structure of populations of two species of Chthamalus (Crustacea: Cirripedia) in the north-east Atlantic and Mediterranean 总被引:2,自引:0,他引:2
Protein electrophoresis on starch gels was used to investigate population genetic structure of the barnacles Chthamalus
montagui
Southward and C. stellatus (Poli) over their north-east Atlantic and Mediterranean ranges. In each species, a single locus exhibited marked differentiation
of allele frequencies between Atlantic and Mediterranean localities; in C. stellatus, genetic differentiation between the two basins had not previously been noted. In both species, mean heterozygosity per locus
appeared higher in the Mediterranean samples than in the Atlantic, and Mediterranean populations had more alleles at the loci
studied. Possible explanations for the differentiation between the Atlantic and the Mediterranean populations are discussed.
Received: 30 May 1996 / Accepted: 17 September 1996 相似文献
8.
The genetic population structure of red grouper, Epinephelus morio (Valenciennes), and scamp, Mycteroperca phenax Jordan and Swain, from the southeastern U.S. Atlantic coast and the Gulf of Mexico was examined using nuclear microsatellite DNA markers in order to test the null hypothesis of panmixia throughout this range. Physical and biological data indicate that relatively isolated populations of these fish exist. Genetic variation was assessed at four microsatellite loci in red grouper and six loci in scamp. The fish were collected on different dates between 1991 and 2001. The microsatellite loci were highly polymorphic, with an average expected heterozygosity of 0.75 in red grouper and 0.68 in scamp. Heterozygote deficiencies (significant deviations from Hardy–Weinberg equilibrium, HWE) were found at two of four loci in all red grouper samples except the eastern Gulf of Mexico, and for all red grouper combined. In contrast, all loci conformed to HWE in the separate scamp samples. Minimal genetic differences distinguished southeastern U.S. Atlantic or Mexican red grouper from other localities, and no indication of genetic differentiation was observed in scamp. This large-scale genetic homogeneity may be attributed to ongoing gene flow and/or historical contact between present-day populations. For management purposes, genetic homogeneity does not necessarily imply a single stock. Because larval dispersal may be sufficient to homogenize gene frequencies but not to replenish depleted stocks, other data must be considered in the management of these species.Electronic Supplementary Material Supplementary material is available in the online version of this article at .Communicated by J.P. Grassle, New Brunswick 相似文献
9.
Multi-marker estimate of genetic connectivity of sole (Solea solea) in the North-East Atlantic Ocean
E. L. Cuveliers M. H. D. Larmuseau B. Hellemans S. L. N. A. Verherstraeten F. A. M. Volckaert G. E. Maes 《Marine Biology》2012,159(6):1239-1253
A thorough knowledge on the genetic connectivity of marine populations is important for fisheries management and conservation.
Using a dense population sampling design and two types of neutral molecular markers (10 nuclear microsatellite loci and a
mtDNA cytochrome b fragment), we inferred the genetic connectivity among the main known spawning grounds of sole (Solea solea L.) in the North-East Atlantic Ocean. The results revealed a clear genetic structure for sole in the North-East Atlantic
Ocean with at least three different populations, namely the Kattegat/Skagerrak region, the North Sea and the Bay of Biscay,
and with indications for a fourth population, namely the Irish/Celtic Sea. The lack of genetically meaningful differences
between biological populations within the southern North Sea is likely due to a large effective population size and sufficient
connection (gene flow) between populations. Nevertheless, an isolation-by-distance pattern was found based on microsatellite
genotyping, while no such pattern was observed with the cytochrome b marker, indicating an historical pattern prevailing in the latter marker. Our results demonstrate the importance of a combined
multi-marker approach to understand the connectivity among marine populations at region scales. 相似文献
10.
This study investigated the utility of microsatellite markers for providing information on levels of population connectivity
for a low dispersing reef fish in New South Wales (NSW), Australia, at scales ≤400 km. It was hypothesized that the temperate
damselfish Parma
microlepis, which produces benthic eggs and has limited post-settlement dispersal, would exhibit spatial genetic structure and a significant
pattern of isolation-by-distance (IBD). A fully nested hierarchical sampling design incorporating three spatial scales (sites,
location and regions, separated by 1–2, 10–50 and 70–80 km respectively) was used to determine genetic variability at seven
microsatellite loci. Broad-scale genetic homogeneity and lack of IBD was well supported by single and multi-locus analyses.
The proportion of the total genetic variation attributable to differences among regions, locations or sites was effectively
zero (Φ/R-statistics ≤0.007). The geographic distribution of genetic diversity and levels of polymorphism (H
E 0.21–0.95) indicate high mutation rates, large effective population sizes, and high rates of gene flow. Significant gene
flow may be driven by factors influencing pre-settlement dispersal, including the East Australian Current (EAC) and habitat
continuity. Genetic connectivity may not reflect demographically important connectivity, but does imply that P. microlepis populations are well connected from an evolutionary perspective. Total observed genetic diversity was accounted for within
1–2 km of reef and could be represented within small Marine Protected Areas. Reef fishes in NSW which have life histories
similar to P. microlepis (e.g. pre-settlement durations ≥2 weeks) are also likely to exhibit genetic homogeneity. Genetic markers are, therefore,
most likely to provide information on demographically relevant connectivity for species with lower dispersal capabilities,
small population sizes, short life spans, and whose habitats are rare, or patchily distributed along-shore.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
11.
The mechanisms driving genetic structure in marine systems are elusive due to the difficulty of identifying temporal and spatial barriers to dispersal. By studying marine invertebrate species with limited dispersal potential, genetic structure can be directly related to physical and biological factors restricting connectivity. In the northwest Atlantic, the benthic brood-rearing amphipod Corophium volutator is distributed across basins with distinct circulation patterns and has the potential to disperse passively during its adult stage. We analyzed spatial genetic variation and migration rates across C. volutator’s North American range with sequence data for mitochondrial DNA and three novel nuclear markers using frequency and coalescent-based methods. We found low genetic differentiation within basins, but strong subdivision within the Bay of Fundy and a striking biogeographic break between the Bay of Fundy and Gulf of Maine, suggesting that genetic drift may act on populations in which connectivity is restricted due to the limitation of passive dispersal by hydrological patterns. 相似文献
12.
Megrim, Lepidorhombus whiffiagonis, and four spot megrim, Lepidorhombus boscii, are two marine fish species of high commercial interest. Despite their quite heavy exploitation little is known on the genetic
structure of their populations. The present work aimed at characterizing the first seven microsatellites markers available
for the two megrim species. These new markers were in a second step employed to describe the population structure of the two
species among their almost entire habitat range (Atlantic and Mediterranean samples). Our study confirmed the existence of
a strong genetic difference between Atlantic and Mediterranean megrim species already described in the literature for L. whiffiagonis on the basis of variations at ribosomal genes. Additionally our analysis gave the first evidences of a strong genetic differentiation
among Atlantic populations in both megrim species (within Atlantic global FST in L. whiffiagonis and L. boscii were respectively 0.158 and 0.145). When describing megrim population structure, the comparison between allele-frequency-based
tests (FST comparisons) and genotype-based inferences (Bayesian approach) gave evidences of a hierarchical structure of the populations.
In conclusion, our work enlighten the existence of two different stocks within the Atlantic Ocean and one in the Mediterranean
Sea that will clearly need to be managed separately. As the present results do not fully support the current megrim stock
boundaries they will surely help to rethink megrim management policies in the future. 相似文献
13.
Zoë Anne Doubleday Jayson M. Semmens Adam J. Smolenski Paul W. Shaw 《Marine Biology》2009,156(6):1183-1192
Five polymorphic microsatellite loci were developed and then used to assess the population genetic structure of a commercially
harvested merobenthic octopus species (Octopus maorum) in south-east Australian and New Zealand (NZ) waters. Beak and stylet morphometrics were also used to assess population
differentiation in conjunction with the genetic data. Genetic variation across all loci and all sampled populations was very
high (mean number alleles = 15, mean expected heterozygosity = 0.85). Microsatellites revealed significant genetic structuring
(overall F
ST = 0.024, p < 0.001), which did not fit an isolation-by-distance model of population differentiation. Divergence was observed between
Australian and NZ populations, between South Australia and north-east Tasmania, and between two relatively proximate Tasmanian
sites. South Australian and southern Tasmanian populations were genetically homogeneous, indicating a level of connectivity
on a scale of 1,500 km. Morphometric data also indicated significant differences between Australian and NZ populations. The
patterns of population structuring identified can be explained largely in relation to regional oceanographic features. 相似文献
14.
Nathan L. Kirk Jason P. Andras C. Drew Harvell Scott R. Santos Mary Alice Coffroth 《Marine Biology》2009,156(8):1609-1623
Numerous marine invertebrates form endosymbiotic relationships with dinoflagellates in the genus Symbiodinium. However, few studies have examined the fine-scale population structure of these symbionts. Here, we describe the genetic
structure of Symbiodinium type “B1/B184” inhabiting the gorgonian Gorgonia
ventalina along the Florida Keys. Six polymorphic microsatellite loci were utilized to examine 16 populations along the Upper, Middle,
and Lower Keys spanning a range of ~200 km. Multiple statistical tests detected significant differentiation in 54–92% of the
120 possible pairwise comparisons between localities, suggesting low levels of gene flow in these dinoflagellates. In general,
populations clustered by geographic region and/or reefs in close proximity. Some of the sharpest population differentiation
was detected between Symbiodinium from deep and shallow sites on the same reef. In spite of the high degree of population structure, alleles and genotypes
were shared among localities, indicating some connectivity between Symbiodinium populations associated with G. ventalina.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
15.
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. 相似文献
16.
Lane snappers (Lutjanus synagris), sampled from eight localities in the northern Gulf of Mexico (Gulf) and one locality along the Atlantic coast of Florida,
were assayed for allelic variation at 14 nuclear-encoded microsatellites and for sequence variation in a 590 base-pair fragment
of the mitochondrially encoded ND-4 gene (mtDNA). Significant heterogeneity among the nine localities in both microsatellite
allele and genotype distributions and mtDNA haplotype distributions was indicated by exact tests and by analysis of molecular
variance (AMOVA). Exact tests between pairs of localities and spatial analysis of molecular variance (SAMOVA) for both microsatellites
and mtDNA revealed two genetically distinct groups: a Western Group that included six localities from the northwestern and
northcentral Gulf and an Eastern Group that included three localities, one from the west coast of Florida, one from the Florida
Keys, and one from the east (Atlantic) coast of Florida. The between-groups component of molecular variance was significant
for both microsatellites (Φ
CT = 0.016, P = 0.009) and mtDNA (Φ
CT = 0.208, P = 0.010). Exact tests between pairs of localities within each group and spatial autocorrelation analysis did not reveal genetic
heterogeneity or an isolation-by-distance effect among localities within either group. MtDNA haplotype diversity was significantly
less (P < 0.0001) in the Western Group than in the Eastern Group; microsatellite allelic richness and gene diversity also were significantly
less in the Western Group (P = 0.015 and 0.013, respectively). The difference in genetic variability between the two groups may reflect reduced effective
population size in the Western Group and/or asymmetric rates of genetic migration. The relative difference in variability
between the two groups was substantially greater in mtDNA and may reflect one or more mtDNA selective sweeps; tests of neutrality
of the mtDNA data were consistent with this possibility. Bayesian analysis of genetic demography indicated that both groups
have experienced a historical decline in effective population size, with the decline being greater in the Western Group. Maximum-likelihood
analysis of microsatellite data indicated significant asymmetry in average, long-term migration rates between the two groups,
with roughly twofold greater migration from the Western Group to the Eastern Group. The difference in mtDNA variability and
the order-of-magnitude difference in genetic divergence between mtDNA and microsatellites may reflect different demographic
events affecting mtDNA disproportionately and/or a sexual and/or spatial bias in gene flow and dispersal. The spatial discontinuity
among lane snappers in the region corresponds to a known zone of vicariance in other marine species. The evidence of two genetically
distinct groupings (stocks) has implications for management of lane snapper resources in the northern Gulf. 相似文献
17.
Furcellaria lumbricalis is a red algae occurring in low salinity to fully marine conditions. Here, both putatively neutral and EST-derived microsatellite
markers were developed and used to examine the genetic structure of northern European populations inhabiting different salinity
conditions ranging from 35 to 3.6 psu. The amount of genetic variation did not differ between ocean and brackish populations,
but differences were observed between marker types; EST-derived markers possessed less variation and showed greater differentiation
than the putatively neutral microsatellites. No multicopy multilocus genotypes were detected despite expected asexuality in
brackish populations. The Bayesian STRUCTURE analysis, when conducted for expressed marker data, indicated the presence of
two main clusters, the Atlantic Ocean and Baltic Sea, while no clear structuring was observed based on putatively neutral
microsatellites. The moderate level of genetic differentiation at neutral loci is probably due to genetic drift, a feasible
explanation considering long distances between many populations, while the high level of differentiation in EST-linked markers
reflects selection pressures. 相似文献
18.
Albacore (Thunnus alalunga) is a highly migratory pelagic species distributed in all tropical and temperate oceans. Recent analyses using both mitochondrial DNA (mtDNA) and nuclear DNA markers have demonstrated genetic subdivision within and between Atlantic and Pacific populations. However, although numerous biological differences have been reported for Atlantic and Mediterranean albacore, the genetic differentiation for these basins has not been demonstrated. We characterized 373 base pairs of nucleotide sequence from the mitochondrial DNA control region of 134 individuals collected in the Pacific (n=30), the northeast (NE) Atlantic (n=54) and the Mediterranean (n=50). Analysis of molecular variance (AMOVA) revealed a small, but highly significant, proportion of genetic variation separating these three regions (st =0.041; P=0.009), a pattern also supported by pairwise comparisons. These results demonstrate for the first time the genetic distinctiveness of the Mediterranean albacore from the NE Atlantic population giving support to the current management practices based on separate units. This outcome is concordant with reported migratory movements related to reproductive behavior between the NE Atlantic and the Mediterranean Sea. Additionally, the phylogenetic analyses of DNA sequences revealed the presence of a shallow genetic discontinuity with no geographic association. These two phylogroups are more likely the result of the demographic history of this species (i.e. long demographic stable history) as opposed to historical vicariance as has been proposed for other highly migratory fishes.Communicated by P.W. Sammarco, Chauvin 相似文献
19.
S. M. Francisco R. Castilho M. Soares L. Congiu A. Brito M. N. Vieira V. C. Almada 《Marine Biology》2009,156(7):1421-1432
A fragment of the mitochondrial control region was used to assess phylogeographic patterns and historical demography of the
sand-smelt Atherina presbyter in the North-eastern Atlantic, covering its geographical range. A striking result is the highly marked differentiation between
the Canary Islands population and western European ones. A genetic structure among European populations of A. presbyter was revealed, with a pattern of isolation-by-distance or a gradient effect at a scale of hundreds kilometres, an uncommon
pattern likely related to the biological and life-history traits of the sand-smelt. The northern European populations present
a much lower genetic diversity when compared to southern populations, which is consistent with a recent colonization from
southern populations. The results showed signs of Pleistocene signatures, with the population age estimates for the European
populations being clearly older than the Last Glacial Maximum (18,000 years bp). Nevertheless, paleotemperature reconstructions
show that the sand-smelt could not have inhabited the western European shores during the last glacial phase.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.
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. 相似文献