共查询到20条相似文献,搜索用时 46 毫秒
1.
Starch-gel electrophoresis of allozymes was used to differentiate the two red mullet species (Mullus barbatus L. and M. surmuletus L.) in the Mediterranean Sea and, further, to investigate the genetic stock structure of M. barbatus in the eastern Mediterranean area. Twenty putative enzyme-coding loci were examined in eight M. barbatus samples caught in the Aegean and Ionian Seas (Greece) and in the Gulf of Lion (France), and two M. surmuletus samples caught in the Aegean and Gulf of Lion. A high degree of genetic polymorphism was found in both species. Species-specific
electrophoretic patterns were found in PGI* and PGM*. Estimates of variance of allele frequencies among samples (F
ST) and 2 analyses both revealed significant differences (P < 0.05) among the M. barbatus samples. Most of the genetic variation was among samples regardless of region. The mean value of Nei's genetic distance between
the two species was 0.329. Genetic distance among M. barbatus samples was low (maximum Nei's D = 0.012), with the sample from Platania differing most from other M. barbatus samples. This is probably be due to founder effects existing at this area. These results suggest that allozyme analysis may
provide important information on the genetic structure of the red mullet to ensure sustainable management of this species.
Received: 7 May 1997 / Accepted: 13 October 1997 相似文献
2.
Results of isozyme electrophoresis were used to explore the genetic relationships between several Mediterranean morphs of
Cerithium (Gastropoda: Prosobranchia), for which taxonomy is currently uncertain because of high intraspecific variability and low
interspecific differentiation. The large species, classically known as C. vulgatum Bruguière, 1789 was identified at four sites (two in the French Mediterranean and two in southern Spain). Two different larval
types were found in the French sites, but poecilogony could not be demonstrated. Individuals collected from harbours were
not genetically distinct from open-sea populations of classic C. vulgatum. However, a population in the Embiez lagoon (French Mediterranean) which morphologically resembles C. vulgatum did display distinct genetic traits, supporting its status as a separate species. Of the small Cerithium species usually known as C. rupestre, two sympatric species (C.“rupestre” Risso, 1826 and C. lividulum Risso, 1826) were distinguished. Genotype frequencies within the analysed populations revealed much heterozygote deficiency.
F
ST
values (fixation index measuring the effects of population subdivision) suggest a higher genetic differentiation for C. lividulum populations than for C. vulgatum populations. We assume that a high larval dispersal capability (via planktotrophy) allows a high gene flow between populations
of C. vulgatum.
Received: 24 November 1998 / Accepted: 24 September 1999 相似文献
3.
This paper reports data on 28 allozyme loci in wild and artificially reared sea bass (Dicentrarchus labrax) samples, originating from either coastal lagoon or marine sites in the Mediterranean Sea. F
ST analysis (θ estimator) indicated strong genetic structuring among populations; around 34% of the overall genetic variation
is due to interpopulation variation. Pairwise θ estimates showed that, on average, the degree of genetic structuring was much
higher between marine populations than between samples from lagoons. Six polymorphic loci showed differences in allele frequencies
between marine and lagoon samples. Multivariate analyses of individual allozymic profiles and of allele frequencies suggested
that different arrays of genotypes prevail in lagoons compared to marine samples, particularly at those loci that, on the
basis of previous acclimation experiments, had been implicated in adaptation to freshwater. On the other hand, variation at
“neutral” allozyme loci reflects to a greater extent the geographic location of populations. Allozyme differentiation was
also studied in a D. labrax population from the Portuguese coast. Average genetic distance between this population and the Mediterranean populations
was quite high (Nei's D = 0.236) and calls into question the taxonomic status of the Portuguese population. Finally, genetic relationships between
D. labrax and D. punctatus were evaluated. Average Nei's D was 0.648, revealing high genetic differentiation between the two species, even for two sympatric populations of these species
in Egypt; thus gene flow was not indicated between species.
Received: 24 October 1996 / Accepted: 27 November 1996 相似文献
4.
Allozyme variation in global populations of striped mullet, Mugil cephalus (Pisces: Mugilidae) 总被引:5,自引:0,他引:5
The striped mullet, Mugil cephalus Linnaeus, 1758, is one of the few species of marine shore fish with a worldwide circumtropical distribution. Because of this
distribution and the dependency of M. cephalus on coastal waters during various phases of its life cycle, as well as nearshore living habits, questions have been raised
regarding levels of genetic divergence and gene flow among transoceanic populations. To cast more light on this, allozyme
variation at 27 presumptive gene loci was investigated in ten globally diverse populations. The observed heterozygosity ranged
from 0.018 (Hawaii) to 0.081 (Florida), averaging 0.050. The proportion of polymorphic loci showed a similar trend. Several
populations were characterised by fixed allelic differences. Estimated gene diversities were very high, the allele frequency
variation among populations was found to be 68%; genetic distances reached 0.242, with an average of 0.117. Estimated rates
of gene flow were high among Mediterranean populations (Nm = 7.26), and between Mediterranean and East Atlantic populations (Nm= 2.86), but extremely low between non-contiguous populations within the Indian, Pacific and Atlantic Oceans, where Nm ranged from 0.03 to 0.05.
Received: 7 April 1997 / Accepted: 4 February 1998 相似文献
5.
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
6.
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
7.
C. S. McFadden 《Marine Biology》1999,133(2):171-184
Species boundaries among taxa of colonial marine organisms are often obscured by intraspecific morphological and ecological
variation; genetic comparisons of recognized “ecotypes” frequently reveal them to be reproductively isolated species. Based
on morphological similarities, it has been proposed that the Mediterranean soft coral Alcyonium (=Parerythropodium) coralloides Pallas, 1766 and its Atlantic congener A. hibernicum belong to one highly variable and geographically widespread species, A. coralloides. I collected A. coralloides from ten Atlantic and three Mediterranean locations in 1990 and 1994, and used differences in colony form, substrate use
and color to separate them into five distinct morphotypes. Two occur sympatrically in the Mediterranean (M1, M2) and three
have overlapping distributions in the Atlantic (A1, A2, A3). I used allozyme electrophoresis to compare morphotypes genetically
at 14 enzyme loci. Where two morphotypes occurred sympatrically, fixed allelic differences at 4 to 6 loci indicated reproductive
isolation. In all but one pairwise comparison (M1 and A2), morphotypes whose ranges did not overlap were also separated by
large genetic distances. From these results I suggest that the five morphotypes represent four distinct species. A. coralloides comprises two morphotypes (M1, A2) with relatively high genetic identity. A. hibernicum (=A1) is reproductively isolated from A. coralloides and should be retained as a valid species; levels of genetic diversity and heterozygosity within populations support the
absence of outcrossing in this reportedly asexual species. Morphotypes M2 and A3 are also reproductively isolated from A. coralloides; they are taxonomically distinct from but belong to the same phylogenetic clade as A. hibernicum. Although preliminary observations suggest that differences in reproductive timing maintain species boundaries in sympatry,
wider geographic sampling will be required to elucidate the events leading to speciation within this species complex.
Received: 8 May 1998 / Accepted: 8 October 1998 相似文献
8.
Genetic divergence and phylogenetic inferences in five species of Mugilidae (Pisces: Perciformes) 总被引:4,自引:0,他引:4
Allozyme electrophoresis was used to compare the genetic divergence of global populations of Mugil cephalus Linnaeus, 1758 and two congeneric [M.␣curema Cuvier & Valenciennes, 1836; M. gyrans (Jordan & Gilbert, 1885)] and two more distantly related [Liza ramada (Risso, 1826); Xenomugil thoburni (Jordan & Starks, 1896)] species on the basis of 18 enzyme loci. The amount of genetic divergence among the species examined
is in agreement with their present systematic status, the differences being larger among non-congeneric species than among
species of the same genus. Intraspecific genetic distances in M. cephalus (average Nei's D= 0.154), although higher than those reported for conspecific populations of fish, appear to be small when compared to the
interspecific values among mugilid species (0.821 ≤ Nei's D ≤ 1.744). Phylogenetic trees obtained by genetic distance methods and discrete character parsimony analysis were of similar
topology, except for the relationships within the genus Mugil and for the arrangement of M. cephalus populations.
Received: 7 April 1997 / Accepted: 4 February 1998 相似文献
9.
Stock heterogeneity was investigated in albacore tuna (Thunnus alalunga, Bonnaterre 1788), a commercially important species in the North Atlantic Ocean and Mediterranean Sea. Twelve polymorphic
microsatellite loci were examined in 581 albacore tuna from nine locations, four in the north-east Atlantic Ocean (NEA), three
in the Mediterranean Sea (MED) and two in the south-western Pacific Ocean (SWP). Maximum numbers of alleles per locus ranged
from 9 to 38 (sample mean, 5.2–22.6 per locus; overall mean, 14.2 ± 0.47 SE), and observed heterozygosities per locus ranged
from 0.44 to 1.00 (overall mean: 0.79 ± 0.19 SE). Significant deficits of heterozygotes were observed in 20% of tests. Multilocus
F
ST values were observed ranging from 0.00 to Θ = 0.036 and Θ′ = 0.253, with a mean of Θ = 0.013 and Θ′ = 0.079. Pairwise F
ST values showed that the SWP, NEA and MED stocks were significantly distinct from one another, thus corroborating findings
in previous studies based on mitochondrial DNA, nuclear DNA (other than microsatellites) and allozyme analyses. Heterogeneity
was observed for the first time between samples within the Mediterranean Sea. GENELAND indicated the potential presence of
three populations across the NEA and two separate populations in the Mediterranean Sea. Observed genetic structure may be
related to migration patterns and timing of movements of subpopulations to the feeding grounds in either summer or autumn.
We suggest that a more intensive survey be conducted throughout the entire fishing season to ratify or refute the currently
accepted genetic homogeneity within the NEA albacore stock. 相似文献
10.
Genetic structure of the flounders Platichthys flesus and P. stellatus at different geographic scales 总被引:1,自引:0,他引:1
The genetic structure of the flounders Platichthys flesus L. and P. stellatus Pallas was investigated on different spatial scales through analysis of allozyme variation at 7 to 24 polymorphic loci in
samples collected from different regions (Baltic Sea, North Sea, Brittany, Portugal, western Mediterranean, Adriatic Sea,
Aegean Sea and Japan) in 1984 to 1987. No geographic variation was evident within a region. Some pattern of differentiation
by distance was inferred within the Atlantic, while the Mediterranean comprised three geographically isolated populations
and was itself geographically isolated from the Atlantic (fixed allele differences at up to three loci were found among P. flesus populations from the Atlantic, the western Mediterranean, the Adriatic Sea, the Aegean Sea and also P. stellatus from the coast of Japan). Sea temperature during the reproductive period probably acts as a barrier to gene flow between
populations. Genetic distances among European flounder populations (P. flesus) were higher than, or of the same magnitude as, the genetic distance between Pacific (P. stellatus) and European flounder populations, suggesting that P. flesus is paraphyletic and/or there is no phylogenetic basis to recognising P. stellatus as a different species. The divergence between P. flesus and P. stellatus was thus inferred to be more recent than the divergence between the present P. flesus populations from the NE Atlantic and eastern Mediterranean. The eastern Mediterranean populations are thought to originate
from the colonisation of the Mediterranean by a proto-P. flesus/P. stellatus ancestor, whereas the present western Mediterranean population has undergone a more recent colonisation event by P. flesus. Patterns of mitochondrial DNA variation, established on a smaller array of P. flesus samples, were in accordance with the geographic patterns inferred from the allozyme survey. In addition, they supported the
hypothesis of a two-step colonisation of the western Mediterranean. These results contribute to our understanding of the biogeography
of the Mediterranean marine fauna, especially the group of boreal remnants to which P. flesus belongs.
Received: 7 February 1997 / Accepted: 26 March 1997 相似文献
11.
DNA sequence diversity of octopods was investigated using the mitochondrial cytochrome oxidase III gene (mtCOIII). DNA was
obtained from ethanol- or formalin-fixed tissue of 15 specimens belonging to Octopus mimus Gould, 1852, Octopus vulgaris Cuvier, 1797 and Scaeurgus unicirrhus d'Orbigny, 1840, from coastal waters of the Mediterranean (France), the southwestern Atlantic (Brazil), the Caribbean (Costa
Rica) and the southeastern/tropical Pacific (north Chile/Costa Rica). A 612 bp fragment of the mtCOIII gene was sequenced
and aligned to the orthologous sequences available from northeastern Pacific Octopus species. Possible phylogenetic relationships were reconstructed. The mtCOIII gene tree revealed two main clusters, one comprised
O. rubescens, O. dofleini and O. californicus, while the other included all O. vulgaris specimens, O. bimaculatus, O. bimaculoides and O. mimus. With one exception all South American haplotypes including O. bimaculatus and O. bimaculoides appeared as the sister group of the Mediterranean haplotype of O. vulgaris, indicating that most of the South American O. vulgaris specimens investigated would not belong to the recently redescribed species O. vulgaris restricted to the Mediterranean and eastern Atlantic. The treatment of O. mimus as a species distinct from Mediterranean O. vulgaris is supported by a high nucleotide divergence of 12.7%. Based on the mtCOIII gene tree the existence of cryptic species among
O. vulgaris-like octopods is suggested.
Received: 15 January 1999 / Accepted: 15 October 1999 相似文献
12.
The presence of the paralytic shellfish poisoning (PSP) dinoflagellate Alexandrium catenella in the north western (NW) Mediterranean Sea has been known since 1983. From this date on, the species has spread along the Spanish and Italian coastlines. Information concerning A. catenella isolates in the NW Mediterranean Sea was gained through phylogenetic studies. Twenty established toxic cultures of A. catenella taken from various NW Mediterranean Sea locations were analysed by nucleotide sequencing of the 5.8S rDNA and internal transcribed spacer regions. These rDNA ribosomal markers resulted useful in delineating the phylogenetic position of this species in the genus Alexandrium as well as in determining relationships between A. catenella isolates from different geographic areas. The phylogenetic position of the Mediterranean A. catenella ribotype, when compared to the “Alexandrium tamarense/catenella/fundyense species complex”, fits this species complex well. All the Mediterranean A. catenella isolates were constituted by only one genetic ribotype. By comparing the isolate sequences with those of other geographic areas, it revealed that the Mediterranean A. catenella ribotype was closely related to the A. catenella from Japan, Western Pacific Ocean. It was also evident that in temperate Japanese waters, a genetic variability was detected within A. catenella isolates; in fact, all strains resulted divergent showing as many as 15 mutational steps. The possibility that A. catenella has been recently introduced into the Mediterranean basin from temperate Asian areas is discussed. 相似文献
13.
Z. Mamuris A. P. Apostolidis A. J. Theodorou C. Triantaphyllidis 《Marine Biology》1998,132(2):171-178
The random amplified polymorphic DNA (RAPD) technique was used to evaluate genetic affinities among eight red mullet (Mullus barbatus L., 1758) samples from the Mediterranean Sea. Twenty-nine random primers were used. Despite the variability which was found
within samples, no specific RAPD marker for the discrimination of the populations was detected. The data analysis revealed
that the genetic diversity among populations is positively related to their geographic distances. The results of this study
indicate that the estimated intraspecific variation may be more␣pronounced with RAPD markers than with allozymes when the
two approaches are applied on the same populations.
Received: 7 November 1997 / Accepted: 30 May 1998 相似文献
14.
Gloria Antonini Paolo Audisio Emiliano Mancini Alessio De Biase Carlo Tronci Giulia Rossetti Marco Trizzino 《Marine Biology》2010,157(2):371-381
Marine rock-pools, commonly found along the Mediterranean coasts, are isolated patches of habitat characterised by large spatial
and temporal variations. The phylogeography of Calobius quadricollis and C. urbanelliae, two sibling species of moss beetles (Coleoptera, Hydraenidae) inhabiting Italian temporary marine rock-pool ecosystems,
were studied using mitochondrial cytochrome c oxidase subunit I (COI). Our data suggest a strong association between the scored
genetic variability and the geographical distribution of populations sampled for both species. These analyses provided evidences
of episodic species range expansion and fragmentation, recurrent “flush and crash” and bottleneck episodes probably occurring
during the Glacial Cycles. The observed phylogeographical pattern is probably related to the historical and biogeographical
processes of Mediterranean areas, as well as both to the ephemeral habitat tipology and limited dispersal ability of these
beetles. 相似文献
15.
An analysis of the population genetics of the meiofaunal polychaete Petitia amphophthalma Siewing, 1956, in which the RAPD-PCR method was applied to 103 individuals from eight populations, some of them very far
apart (Atlantic: Florida, Tenerife, France; Mediterranean: two Greek islands, Tunisia; Red Sea: Egypt), gave closely reproducible
results. In the band patterns produced with 13 decamer primers, a total of 195 genetic characters was detected. The data were
evaluated by a number of methods, including the cluster programs UPGMA, WPGMA and neighbour-joining. The detected genetic
distances between the populations vary between 58.9 and 66.6, but 97% of the genetic characters, although polymorphic, are
found in at least two populations and usually in all the others as well. Phenograms of the analyses find four population clusters
[Florida, France (Atlantic), the Mediterranean and Tenerife]. They are, however, not completely congruent and show low bootstrap
values at the junction points of the clusters (with the exception of the Tenerife cluster). Mediterranean P. amphophthalma form a cohesive population, although within it the genetic distances are graded in parallel with the geographic distances
between the sites. The colonization of Tenerife, an island of relatively recent volcanic origin, can be taken as evidence
that this meiofaunal species can become dispersed not only along coastlines but also across expanses of open water. However,
the severely restricted variability of these populations implies that in this case a founder effect has operated, and that
transport over open water is not a routine event but extremely rare. The absence of the species on the Australian coast and,
for instance, on the Galapagos Islands indicates that there has been no continuous gene flow across the oceans. The idea that
all the populations investigated belong to one cosmopolitan species is discussed.
Received: 17 October 1997 / Accepted: 15 April 1998 相似文献
16.
F. Maltagliati A. P. Peru M. Casu F. Rossi C. Lardicci M. Curini-Galletti A. Castelli 《Marine Biology》2000,136(5):871-879
The genetic relationships between morphologically indistinguishable marine and brackish populations of Syllis gracilis Grube, 1840 (Polychaeta: Syllidae) were studied by means of allozyme electrophoresis. Samples of S. gracilis from marine coastal and brackish-water habitats were examined for variation at 13 presumptive loci. In addition, a sample
of the closely related species S. prolifera (Krohn, 1852) was analysed. Five loci were multiallelic in at least one population of S. gracilis and eight loci in S. prolifera. Low to moderate levels of within-population genetic variability were found, with average expected heterozygosity values
ranging from H = 0.068 (±0.043 SE) to 0.187 (±0.069 SE) in the populations of S. gracilis; higher values were found in S. prolifera (H = 0.325 ± 0.076). The presence of various private alleles indicated a marked genetic divergence among populations of S. gracilis, with Nei's genetic distances ranging from D = 0.000 to 0.833 and a highly significant F
ST value. Furthermore, evidence for strong genetic heterogeneity between two sympatric marine populations was found. UPGMA cluster
analysis and multidimensional scaling pointed out a clear genetic divergence between brackish and marine populations. At least
two genetically divergent entities occurred in marine and brackish habitats. This could be due to local adaptation of individuals
coming from marine populations to brackish habitats, but more presumably to the occurrence of a species complex within S. gracilis.
Received: 6 June 1999 / Accepted: 7 February 2000 相似文献
17.
Growth parameters of deep-water decapod crustaceans in the Northwestern Mediterranean Sea: a comparative approach 总被引:1,自引:1,他引:0
Relative and absolute growth were studied in 17 species of deep-water decapod crustaceans, spanning nine families of six
different infra-orders, in the Northwestern Mediterranean Sea. The overall maximum abundance of these species lay between
200 m and 750 m (i.e. upper- and mid-slope species). Relative and absolute growth rates were compared by contrasting the slopes
of the size–weight relationships for the different species and calculating the von Bertalanffy growth-equation parameters
asymptotic length (L
∞
) and growth rate (k). The size–weight relationships differed significantly as function of the species' life habits. The results revealed a significant
decrease in weight relative to size in mesopelagic species (which carry out diel vertical migrations), an almost isometric
relationship between size and weight in the less mobile nektobenthic species, and a significant increase in weight relative
to size in strictly benthic species. The mean allometric coefficient for each group increased significantly from mesopelagic
to benthic species. However, no general trend was observed in the growth-performance index, Φ (an index used to compare absolute
growth rates between species, as a function of habit and depth of maximum abundance for all species combined), suggesting
that the deep-water decapod crustaceans studied have similar absolute growth rates. Nevertheless, comparison of growth-parameter
and growth-performance index values within families did reveal differences. Mesopelagic species of the families Sergestoidae
and Pasiphaeidae showed slightly increased growth rates with increasing depth of distribution. Nektobenthic species of the
genus Plesionika followed a trend opposite to that shown by mesopelagic species, with a higher growth rate for the shallowest-dwelling species
(P. heterocarpus) than the deepest-dwelling species (P. acanthonotus). Taking growth as one of the major components of an organism's energy budget, the growth rates for the decapod crustacean
species in this study were significantly lower than those reported in the literature for shallow-water penaeid crustacean
species (which are distributed in higher-temperature habitats than deep-water Mediterranean crustaceans) and higher than those
reported for mesopelagic myctophid fish species. Hence, the well-defined growth trends shown by deep-water decapod crustacean
species in the Northwestern Mediterranean Sea, compared to the less well-defined trends in the other taxa, is discussed in
the framework of the overall dynamics of their ecosystem.
Received: 25 May 1998 / Accepted: 27 September 1999 相似文献
18.
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. 相似文献
19.
Effects of dispersal and mating systems on the genetic structure of populations were evaluated by comparing five sea anemones:
four Epiactis species that brood their offspring to the juvenile stage and one Anthopleura species that broadcasts gametes and has pelagic, planktotrophic larvae. The anemones were sampled at sites ranging from British
Columbia to southern California between 1988 and 1992 and were analyzed by enzyme electrophoresis and by multilocus DNA-fingerprinting.
Results were only partially consistent with expectations. While all four brooding species had lower observed heterozygosities
than the broadcasting species, not all brooding species had greater population subdivision than the broadcasting species.
The self-fertile E. prolifera had the expected evidence of intense local inbreeding ( f = 0.955); unexpectedly, the cross-fertile E. lisbethae and E. ritteri also had similar departures from random mating ( f = 0.957 and 0.831, respectively) probably due to biparental inbreeding among near neighbors in small, highly subdivided populations.
Received: 24 May 1996 / Accepted: 12 July 1996 相似文献
20.
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 相似文献