共查询到20条相似文献,搜索用时 62 毫秒
1.
Evolutionary diversification of the broadly distributed copepod sibling species complex Eurytemora affinis has been documented in the northern hemisphere. However, the fine scale geographic distribution, levels of genetic subdivision,
evolutionary, and demographic histories of European populations have been less explored. To gain information on genetic subdivision
and to evaluate heterogeneity among European populations, we analyzed samples from 8 locations from 58° to 45°N and 0° to
23°E, using 549 base pairs of the mitochondrial cytochrome oxidase subunit I (COI) gene. We discovered three distinct lineages
of E. affinis in Western Europe, namely the East Atlantic lineage, the North Sea/English Channel (NSEC) lineage, and the Baltic lineage.
These geographically separated lineages showed sequences divergence of 1.7–2.1%, dating back 1.9 million years (CI: 0.9–3.0
My) with no indication of isolation by distance. Genetic divergence in Europe was much lower than among North American lineages.
Interestingly, genetic structure varied distinctively among the three lineages: the East Atlantic lineage was divided between
the Gironde and the Loire populations, the NSEC lineage comprised one single population unit spanning the Seine, Scheldt and
Elbe rivers and the third lineage was restricted to the Baltic Proper (Sweden). We revealed high haplotype diversity in the
East Atlantic and the Baltic lineages, whereas in the NSEC lineage haplotype diversity was comparatively low. All three lineages
showed signs of at least one demographic expansion event during Pleistocene glaciations that marked their genetic structure.
These results provide a preliminary overview of the genetic structure of E. affinis in Europe. 相似文献
2.
Coelomactra antiquata is a commercially important bivalve species, but has been suffering from severe population decline due to over-exploitation
and the deterioration of environmental conditions. Previous genetic survey of C. antiquata conducted with allozymes combined with morphology revealed high levels of genetic differentiation between northern and southern
populations which suggests a cryptic species might exist in C. antiquata. To test this hypothesis, amplified fragment length polymorphisms (AFLPs) and 16S rRNA gene sequence were used to re-evaluate
the spatial genetic structure of six populations of C. antiquata along the coast of China. Both genetic markers display a sharp genetic break between the four northern populations (northern
lineage) and two southern population (southern lineage). Large numbers of private alleles (AFLP) were found within the northern
or southern populations and a deep divergence of about 6.5% in 16S rRNA gene sequence between the northern and southern lineages
suggests the occurrence of potential cryptic or sibling species of C. antiquata. Applying previously published rates of mutation, divergence between the two lineages is estimated to have occurred approximately
3 million years ago and may be due to allopatric isolation during the middle Pliocene times. While no genetic differentiation
was found within the northern or southern populations in both AFLP and 16S mtDNA markers, the results indicate that the northern
and southern lineage should be managed separately and any translocation between the two areas should be avoided. 相似文献
3.
Phascolosoma perlucens is one of the most common intertidal sipunculan species and has been considered a circumtropical cosmopolitan taxon due to
the presence of a long-lived larva. To verify whether P. perlucens is a true cosmopolitan species or a complex of cryptic forms, we examined the population structure and demographics of 56
putative P. perlucens individuals from 13 localities throughout the tropics. Analysis of two mitochondrial markers, cytochrome c oxidase subunit I and 16S rRNA, suggests high levels of genetic differentiation between distantly located populations of
P. perlucens. At least four different lineages identified morphologically as P. perlucens were distinguished. These lineages are likewise supported by phylogenetic analysis of the two mitochondrial markers and by
the haplotype network analysis. Our results suggest that P. perlucens is a case of overconservative taxonomy, rejecting the alleged cosmopolitanism of P. perlucens. However, cryptic speciation also exists in some areas, including a possible case of geminate species across the Isthmus
of Panama. 相似文献
4.
We explore the phylogeography of the broadcast spawner Marthasterias glacialis along south Europe and Azores. Sequences of the cytochrome c oxidase gene from 225 specimens, belonging to 10 localities, were analysed. We found 73 haplotypes grouped within two lineages
(divergence 2.9%). One lineage was Atlanto–Mediterranean, whereas another one was exclusively Mediterranean. Estimation of
lineages split goes back to 830,000–580,000 (±120,000) years ago. This suggests that sea-level oscillations during the Pleistocene
glaciations promoted gene flow interruption, lineage divergence between basins and cryptic speciation. Secondary contact between
populations allowed a recolonization of the Mediterranean by the Atlantic lineage. When animals of the Atlanto–Mediterranean
lineage were considered separately, F
st index and AMOVA did not show significant differences between populations along either the Iberian Peninsula or basins. Isolation
by distance between populations was not detected, and only populations of Plymouth and Azores showed significant differences
to all the others. The remoteness of Azores islands might explain the structure of this population. Haphazard arrival of larvae
and local extinctions rather than contemporary restricted gene flow might be responsible for the distinctive population structure
of Plymouth. 相似文献
5.
Understanding the evolutionary processes from recent demographic history is especially difficult for interstitial organisms
due to their poorly known natural history. In this study, the genetic variation and population history of the four Ototyphlonemertes (Diesing in Sitz ber Math Nat Kl Akad Wiss Wien 46:413–416, 1863) species were evaluated from samples collected along the Brazilian coast (between 27°31′S and 13°00′W) in 2006. The mitochondrial
region cytochrome c oxidase subunit 3 (COX3) is analyzed to assess the genetic variation of these dioecious species. Although these species have
a sympatric distribution along the coast, our data suggest that their levels of differentiation and their demographic histories
differ sharply. There is strong evidence of gene flow among demes in O. erneba and O. evelinae, and their level of structuring is much lower than for the other two species. Indeed, the COX3 fragment reveals cryptic lineages
in O. lactea and O. parmula. The results seem to contradict the high genetic structuring and low intrapopulational variability expected with the ecological
constriction and habitat discontinuity faced by these organisms, meaning that there might be gene flow among populations or
their dispersal capability has been underestimated. 相似文献
6.
S. Derycke T. Backeljau C. Vlaeminck A. Vierstraete J. Vanfleteren M. Vincx T. Moens 《Marine Biology》2007,151(5):1799-1812
Species identification in the phylum Nematoda is complicated due to the paucity of easily obtainable diagnostic morphological
features. Furthermore, the cosmopolitan distribution of several species despite low dispersal abilities makes cryptic diversity
potentially substantial within this phylum. We conducted a population genetic survey in the marine nematode Geomonhystera disjuncta in Belgium and The Netherlands in two seasons. The mitochondrial cytochrome oxidase c subunit 1 (COI) gene was screened with
the single-strand conformation polymorphism method in 759 individuals. The 43 haplotypes were grouped into five lineages,
with low divergences within (<3%) and high divergences between lineages (>14%). Analysis of the nuclear ITS region yielded
concordant tree topologies, indicating the presence of five cryptic taxa within G. disjuncta. Analysis of Molecular Variance (AMOVA) illustrated a significant structuring in all lineages and temporal fluctuations in
haplotype frequencies within and between locations. Metapopulation dynamics and/or priority effects best explained this structuring.
Finally, our data indicate that the COI gene may be useful for DNA barcoding purposes. 相似文献
7.
A cryptic lineage of hammerhead shark closely related to but evolutionarily distinct from the scalloped hammerhead (Sphyrna lewini) was recently documented in the western North Atlantic Ocean. Here, we demonstrate using nuclear and mitochondrial DNA sequences
that this cryptic lineage also occurs in the western South Atlantic Ocean, extending its distribution >7,000 km from its only
previously reported location. Our results also further validate the existence of this evolutionarily distinct hammerhead shark
lineage. The southern hemisphere cryptic individuals were 1.6 and 5.8% divergent from S. lewini (sensu stricto) for the nuclear internal transcribed spacer 2 (ITS2) and mitochondrial control region loci, respectively, and formed a strongly
supported, reciprocally monophyletic sister group to sympatric S. lewini. Coalescent analysis (ITS2 locus) yielded a divergence estimate of ~4.5 million years between S. lewini and the cryptic lineage. Given expanding concerns about overfishing of the large-bodied hammerhead sharks, this cryptic lineage
needs to be formally recognized and incorporated into shark management and conservation planning to avoid the inadvertent,
potential extirpation of a unique hammerhead lineage. 相似文献
8.
Margherita Sirna Terranova Sabrina Lo Brutto Marco Arculeo Jeffry B. Mitton 《Marine Biology》2006,150(1):89-101
Brachidontes pharaonis (Fisher P, 1870) is an Indo-Pacific mussel that has colonized the Mediterranean Sea via the Suez Canal. Mussels may have migrated by natural dispersal of pelagic larvae, or they may have been transported on the hulls of ships, or in ballast water, or by some combination of these. Mitochondrial COI sequences (618 bp) from 101 mussels from six localities in the central and eastern Mediterranean Sea and from one site in the Red Sea were used to describe population structure. Analysis of molecular variance indicated that frequencies differed among populations, and that 92% of the variation resided within populations. The majority of haplotypes were private alleles. No simple pattern of longitudinal variation was detected for haplotype frequencies, haplotype diversity, or nucleotide diversity. A variety of tree-building algorithms (NJ, MP, ME) gave consistent results, showing two sister groups. One clade had a leucine (L-form) and the other one a methionine (M-form) at the 30th amino acid. These sympatric forms were detected within all localities and they had similar frequencies in males and females. The M- and L-form were separated by a 7.3% sequence divergence, indicating that this is an ancient polymorphism. Closely related species of mussels had exclusively the L-form, so we infer that the M-form evolved from the L-form lineage of B. pharaonis, probably in the northern portion of the Red Sea. Neutrality tests detected an excess of rare mutations, a pattern of variation expected in expanding populations. Patterns of variation detected by Tajima’s D suggest that some form of balancing selection has maintained this polymorphism. 相似文献
9.
Recent reports indicate an extensive amount of molecular evolution separating cryptic taxa as well as significant population
structure at a microgeographical scale. Appropriate molecular markers are particularly suitable for distinguishing cryptic
biological species. In this study, we examine the phylogenetic utility of 16S rRNA in elucidating the evolutionary relationships
within the recently described euryhaline Brachionus plicatilis species complex. In addition, we assess the applicability of this marker in the genetic identification and monitoring of
rotifer populations. We have sequenced a 378-bp fragment of the mitochondrial 16S rRNA gene in laboratory reference strains,
hatchery clones as well as collections from a wild population of the subsaline Lake Koroneia (Northern Greece). Also, restriction
fragment length polymorphism (RFLP) analysis was performed with eight restriction endonucleases. Rotifer samples are distinguished
into six genetically divergent lineages. Average sequence divergence between lineages is 0.1038. The evolutionary relationships
and divergence time-scales revealed with the 16S sequence data are in agreement with previous analyses using different mitochondrial
and nuclear markers. The 16S region appears to have several advantages over other regions of the genome regarding use of species-specific
primers, ease of amplification from single specimens and undiluted informational content over both recent and more ancient
separations. It has also exhibited maximum discriminatory power (100% success) between lineages during RFLP analysis. The
16S assayed region has proven especially informative and consistent in detecting, supporting and establishing the lineage
status within the B. plicatilis species complex both from a phylogenetic perspective and as an identification tool. 相似文献
10.
Physiological studies were made on the crabs Ucides cordatus (L.) and Callinectes danae sampled from populations living in “polluted” mangroves on the southeast littoral of Brazil. Analysis of Cu, Cd, Zn, and
Fe of sediments and crab tissues showed interspecific differences in tissue concentrations, and significantly higher levels
of Cu, Cd, and Zn in “polluted” populations compared to “unpolluted” crabs living in uncontaminated mangrove in the same geographical
area. Individuals of both species from the polluted site showed significantly greater capacities for regulating blood osmotic
concentrations at low salinity (9‰). However, U. cordatus showed a reduced hypo-regulatory ability in 34‰S. Differences in ionoregulation were also seen. “Polluted”C. danae showed significantly higher Na/ K-ATPase levels in posterior gills compared to “unpolluted” crabs. Oxygen consumption rates
(M˙
O2) were elevated in U. cordatus, but depressed in C. danae from the “polluted” population. Individuals of both species from this site showed significantly lower O:N ratios, mainly
because of an increased net efflux of ammonia. Adenylate energy charge (AEC) values of muscle and hepatopancreas in “unpolluted”
and “polluted” populations of both species were not significantly different. These physiological differences are discussed
in relation to the known acute physiological and metabolic effects of heavy metals in crustaceans, and interpretated in the
light of possible adaptive changes following long-term exposure to contamination.
Received: 6 August 1999 / Accepted: 22 June 2000 相似文献
11.
Thomas Remerie Tine Bourgois Danny Peelaers Andy Vierstraete Jacques Vanfleteren Ann Vanreusel 《Marine Biology》2006,149(3):465-481
The phylogeographic patterns among populations of Mesopodopsis slabberi (Crustacea, Mysida), an ecological important mysid species of marine and estuarine habitats, were analysed by means of DNA sequencing of a fragment of the mitochondrial cytochrome c oxidase subunit I (COI) and the 16S ribosomal RNA genes. Samples of M. slabberi collected from five Atlantic and two Western Mediterranean populations were investigated. Very high levels of within-population molecular diversity were observed in all samples (mean h=0.807 and π=0.0083), with exception of the Mediterranean Ebro population which contained only one haplotype. Differentiation among populations was high, and a clear phylogeographic break was observed between the Atlantic and Mediterranean populations. Moreover, a strong differentiation was detected between both populations in the Western Mediterranean Sea (Alicante and Ebro delta), while two divergent lineages occurred in sympatry within the Atlantic Mondego estuary. The high congruence between both the COI and 16S rRNA sequence data, the reciprocal monophyly of the different mitochondrial clades and the levels of nucleotide divergence between them suggest the presence of a complex of cryptic species within M. slabberi. Estimations of divergence time between the different mitochondrial lineages indicate that a split occurred during the late Miocene/early Pliocene. Such a divergence could be concordant with vicariant events during sea-level drops within the Mediterranean region at that time. However, within the Mediterranean Sea, the potential of divergence through ecological diversification cannot be ruled out. 相似文献
12.
We conducted a phylogeographic study of the meiofaunal nemertean Ototyphlonemertes parmula, an apparent species complex from the littoral zone of coarse-grained beaches, using a 494-bp fragment of the mitochondrial
cytochrome oxidase 3 gene (cox3). Six populations from the Gulf and Atlantic coasts of Florida, two from New England, and one from the Caribbean were sampled
in March and August 2005. Three major lineages were identified, separated by cox3 sequence divergence of 16–18%, with partially overlapping ranges. Tests for hybridization using ISSR markers detected nuclear
gene exchange within but not between the major mitochondrial lineages, indicating the presence of cryptic species. One lineage
dominating the Atlantic coast of Florida shows no evidence of geographic structuring. Another lineage shows a phylogenetic
break between the Atlantic and Gulf coasts, suggesting that unsuitable habitat may act as a barrier to dispersal. Long-distance
migration is evidenced by shared haplotypes between Florida and the eastern Caribbean. Overall, the widespread distribution
of individual haplotypes and lack of structuring within geographic regions contrast with O. parmula’s strongly sediment-bound lifestyle. We speculate that dispersal of adults by storms and/or sediment transport may be more
important than few and potentially short-lived planktonic larvae to explain geographic diversity in O. parmula and may be important for meiofauna in general. 相似文献
13.
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
14.
Salima Machkour-MRabet Yann Hénaut Pierre Charruau Muriel Gevrey Peter Winterton Luc Legal 《Marine Biology》2009,156(6):1321-1333
Habitat loss and degradation in the Mexican Caribbean, caused by the development of tourism, have decreased the potential
nesting area for the American crocodile (Crocodylus acutus) and have fragmented the populations of the Yucatan peninsula. Our study investigated five populations (three continental:
North, South, Sian Ka’an, and two insular: Cozumel, Banco Chinchorro) of C. acutus in the Mexican Caribbean using seven different inter simple sequence repeat (ISSR) markers as tools for genetic variability
and population differentiation. Three classification methods were tested and compared: distance analysis, self-organizing
map, and Bayesian methods, to evaluate the resolution of each method with ISSR markers. The 77 loci selected revealed a high
variability between populations (polymorphism from 17% for Sian Ka’an to 75% for Banco Chinchorro) with a total polymorphism
of 84% and a global coefficient of gene differentiation (G
ST
) of 0.296, but low values of Nei’s Gene diversity (from 0.065 for Sian Ka’an to 0.233 for Banco Chinchorro). Our results
suggest elevated inbreeding in all local populations with higher indices for Banco Chinchorro and lower indices for Sian Ka’an.
Three independent classification methods gave similar results, and suggested that most continental individuals are admixtures,
with different levels of introgression, with the sympatric species Crocodylus moreletii. We propose that the islands/atolls remain the sole areas with genetically “pure” American crocodiles and we discuss these
results for future conservation of this endangered crocodile species. 相似文献
15.
Mitochondrial d-loop sequences were analyzed to characterize the phylogeographic and population genetic structure of the
northern clingfish (Gobbiesox maeandricus Girard). Sequence analysis of 378 bp from 111 individuals sampled in 14 localities along the northeast Pacific coast and
within the Strait of Georgia from 1996 to 1999 revealed marked genetic differentiation (Φct=0.247) among regional population groupings. The gene genealogy distinguished two major clades of haplotypes separated by
at least 1.1% sequence divergence. One clade with very low haplotype diversity (h=0.2095, n=18) occurred only within the recently unglaciated Strait of Georgia. The other clade had high haplotype diversity (h=0.8808, n=93) and was found in all populations. High haplotype diversity was found in open coastal populations, both north and south
of the maximum extant of the Wisconsin ice sheet, suggesting that the clingfish range was not pushed to a southern refugium
during the last glacial maximum. A nested clade analysis also did not detect a large northward expansion from a single southern
refugium. The level of sequence divergence and coalescent-based analyses suggest that the observed patterns of polymorphism
are the result of Pleistocene diversification within multiple refugia, followed by population expansion and asymmetrical lineage
introgression.
Received: 5 February 2000 / Accepted: 31 August 2000 相似文献
16.
In a previous study on the kuruma shrimp Penaeus japonicus from the South China Sea, we detected high genetic divergence between two morphologically similar varieties (I and II) with
distinct color banding patterns on the carapace, indicating the occurrence of cryptic species. In the present study, we clarify
the geographical distribution of the two varieties in the western Pacific by investigating the genetic differentiation of
the shrimp from ten localities. Two Mediterranean populations are also included for comparison. Based on the mitochondrial
DNA sequence data, the shrimps are separated into two distinct clades representing the two varieties. Variety I comprises
populations from Japan and China (including Taiwan), while variety II consists of populations from Southeast Asia (Vietnam,
Singapore and the Philippines), Australia and the Mediterranean. Population differentiation is evident in variety II, as supported
by restriction profiles of two mitochondrial markers and analysis of two microsatellite loci. The Australian population is
genetically diverged from the others, whereas the Southeast Asian and Mediterranean populations show a close genetic relationship.
Variety I does not occur in these three localities, while a small proportion of variety II is found along the northern coast
of the South China Sea and Taiwan, which constitute the sympatric zone of the two varieties. The present study reveals high
genetic diversity of P. japonicus. Further studies on the genetic structure of this species complex, particularly the populations in the Indian Ocean and Mediterranean,
are needed not only to understand the evolutionary history of the shrimp, but also to improve the knowledge-based fishery
management and aquaculture development programs of this important biological resource. 相似文献
17.
Phylogenetic relationships among vesicomyid clams (Bivalvia: Vesicomyidae) and their placement within the order Heterodonta
were examined using mitochondrial encoded cytochrome oxidase subunit I (COI) DNA sequences. The presently analyzed vesicomyids
represent a recent monophyletic radiation that probably occurred within the Cenozoic. Nucleotide phylogenetic analyses resolved
discrete clades that were consistent with currently recognized species: Calyptogena magnifica, C. ponderosa, Ectenagena extenta, C. phaseoliformis, Vesicomya cordata, Calyptogena n. sp. (Gulf of Mexico), C. kaikoi, C. nautilei, C. solidissima and C. soyoae (Type-A). However, specimens variously identified as: V. gigas, C. kilmeri, C. pacifica, and V. lepta comprised two “species complexes”, each composed of multiple evolutionary lineages. Most taxa are limited to hydrothermal-vent
or cold-seep habitats, but the “vent” versus “seep” clams do not constitute separate monophyletic groups. Current applications
of the generic names Calyptogena, Ectenagena, and Vesicomya are not consistent with phylogenetic inferences.
Received: 24 July 1997 / Accepted: 22 August 1997 相似文献
18.
Letícia Soares Peter Marra Lindsey Gray Robert E. Ricklefs 《Conservation biology》2017,31(6):1477-1482
Island populations are vulnerable to introduced pathogens, as evidenced by extinction or population decline of several endemic Hawaiian birds caused by the malaria parasite, Plasmodium relictum (order Haemosporida). We analyzed blood samples from 363 birds caught near Guantánamo Bay, Cuba, for the presence of haemosporidian infections. We characterized parasite lineages by determining nucleotide variation of the parasite's mitochondrial cyt b gene. Fifty‐nine individuals were infected, and we identified 7 lineages of haemosporidian parasites. Fifty individuals were infected by 6 Haemoproteus sp. lineages, including a newly characterized lineage of Haem. (Parahaemoproteus) sp. CUH01. Nine individuals carried the P. relictum lineage GRW4, including 5 endemic Cuban Grassquits (Tiaris canorus) and 1 migratory Cape May Warbler (Setophaga tigrina). A sequence of the merozoite surface protein gene from one Cuban Grassquit infected with GRW4 matched that of the Hawaiian haplotype Pr9. Our results indicate that resident and migratory Cuban birds are infected with a malaria lineage that has severely affected populations of several endemic Hawaiian birds. We suggest GRW4 may be associated with the lack of several bird species on Cuba that are ubiquitous elsewhere in the West Indies. From the standpoint of avian conservation in the Caribbean Basin, it will be important to determine the distribution of haemosporidian parasites, especially P. relictum GRW4, in Cuba as well as the pathogenicity of this lineage in species that occur and are absent from Cuba. 相似文献
19.
Julia Bartmess-LeVasseur Carrie L. Branch Sheri A. Browning Jessica L. Owens Todd M. Freeberg 《Behavioral ecology and sociobiology》2010,64(7):1187-1198
Evidence from different chickadee species (Poecile genus) indicates that birds can modify the note composition of their “chick-a-dee” calls in the presence of predator stimuli.
Here, we tested the effects of predator models and the distance of those models on calls of three species foraging together
at feeding stations: Carolina chickadees (Poecile carolinensis) and tufted titmice (Baeolophus bicolor), both members of the Paridae family, and white-breasted nuthatches (Sitta carolinensis), a member of the Sittidae family. Model and distance affected seed-taking rates in all three species. “Chick-a-dee” calling
rates were higher in the predator context for both chickadees and titmice, but we detected no predator context effects on
“quank” call rates for nuthatches. Predator and distance contexts affected acoustic parameters of notes of the “chick-a-dee”
calls of chickadees and titmice; no such effects were detected for nuthatch “quank” calls. These results suggest species differences
in encoding of information in the primary social calls of these three species that commonly occur in multi-species flocks.
Chickadees and titmice are “nuclear” species and nuthatches are “satellite” species, and these different roles might be related
to the differences in vocal signaling that we detected. 相似文献
20.
A.?Triantafyllidis A.?P.?Apostolidis V.?Katsares E.?Kelly J.?Mercer M.?Hughes K.?E.?J?rstad A.?Tsolou R.?Hynes C.?Triantaphyllidis
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. FST analyses also showed significant heterogeneity among the European lobster population samples (FST=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 相似文献