[Show abstract][Hide abstract] ABSTRACT: The small-spotted catshark Scyliorhinus canicula is a small demersal chondrychtian distributed on continental shelf and uppermost slope waters of the Mediterranean Sea and north eastern Atlantic Ocean. It has commercial value in some European regions, whereas in other it is considered a bycatch species. Species’ genetic structure was analysed by means of 578bp mitochondrial COI sequences. A total of 192 individuals (122 obtained in the present work and 70 retrieved from GenBank) from 11 Mediterranean and 1 Atlantic locations were considered. Overall, we detected 25 COI haplotypes, seven of which were newly found. Moreover, a high number of haplotypes were location- and/or region-private. Low values of nucleotidic diversity (total = 0.0024) and moderate to high haplotypic diversity (h = 0.500 to 0.907, total h = 0.810) were found. Significant genetic structuring in the study area was highlighted by AMOVA, -statistics and Bayesian assignment analyses. The Atlantic sample was genetically divergent from Western Mediterranean counterparts and the Adriatic samples diverged from Eastern Mediterranean ones. Instead, Western and Eastern Mediterranean were not significantly divergent, suggesting that the Strait of Sicily is not effective in restricting past or current gene flow. No pattern of isolation by distance was detected. From a fisheries perspective, our results represent the first evidence of genetic structuring in S. canicula and are consistent with the presence of multiple genetic stocks in the study area. Further genetic analyses coupled with a fine grained sampling design are needed to precisely identify the borders of genetic stocks. These data provide a significant contribution for the planning of a long-term effective management policy, which could ensure sustainability of resource exploitation and stock viability.
Fisheries Research 03/2014; 154:11-16. DOI:10.1016/j.fishres.2014.01.021 · 1.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The giant red shrimp, Aristaeomorpha foliacea, is a commercially
important species in the Mediterranean Sea (MED), Mozambique Channel
(MOZ), and north western Australia (AUS). 685 bp of the mitochondrial
COI gene was sequenced in 317 individuals from six Mediterranean and two
Indian Ocean localities. Genetic diversity estimates of Indian Ocean
samples were higher than those of MED counterparts. AMOVA, phylogenetic
tree, haplotype network and Bayesian assignment analyses detected three
haplogroups, corresponding to MED, MOZ and AUS, separated by three and
38 mutational steps, respectively. Within MED shallow genetic divergence
between populations was dependent on local oceanographical
characteristics. Mismatch distribution analysis and neutrality tests
provided a consistent indication of past population expansion in each
region considered. Our results provide the first evidence of genetic
structure in A. foliacea and suggest a scenario of allopatric speciation
within the Indian Ocean that, however needs deeper examination.
Journal of Sea Research 02/2013; 76:146-153. DOI:10.1016/j.seares.2012.08.004 · 1.99 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The blue and red shrimp Aristeus antenantus supports an important commercial fishery in the Western Mediterranean, adjacent Atlantic waters and Mozambique Channel (western Indian Ocean). This study investigates its genetic structure by examining a total of 506 individuals from Mediterranean, Atlantic and Indian Ocean locations. In order to identify putative genetic stocks, sequences from 16S rDNA (546 bp) and COI (514 bp) genes were used. Genetic diversity, estimated by haplotypic and nucleotidic diversity, was lower in the Western Mediterranean than in samples from other locations. The high haplotypic diversity of the Eastern Mediterranean, Atlantic and Indian Ocean samples reflects the occurrence of a number of private haplotypes, which are also responsible for significant genetic divergence between these samples and the Western Mediterranean ones. The analysis of mismatch distributions, neutrality tests, and star-like patterns present in the network of haplotypes provided consistent inference of past population expansion in the Western Mediterranean, Atlantic and Mozambique Channel regions. Our study provides the first evidence of genetic structuring in A. antennatus across its distributional range.
[Show abstract][Hide abstract] ABSTRACT: The red and blue shrimp, Aristeus antennatus, inhabits deep shelf waters in the Mediterranean Sea, where the shallower portion of its distribution supports a large commercial fishery. Recent prospecting surveys in the western Mediterranean have detected virgin stocks dwelling at more than 1000 m, but the extent of gene flow between the exploited shallow-dwelling stock and the deep-dwelling stock is unknown. To investigate the genetic structure of the population and estimate the depth component of gene flow, a portion of the mitochondrial DNA 16S gene (547 pb) was sequenced for 321 individuals from four different depths (350, 700, 1100 and 1500 m) at a location in the Catalan Sea. Haplotype and nucleotide diversity values were low and did not significantly differ across depths. Analysis of molecular variance showed no significant genetic differences between depths. Mismatch distribution and neutrality tests indicated that A. antennatus has undergone recent demographic expansion in the two shallowest layers. Our results suggest that the species is genetically structured as a sort of metapopulation in which gene flow that occurs during the larval and juvenile stages, when larvae are carried downstream and juveniles are carried upstream by cascading, plays an important role in the resilience of the exploited layers.
Scientia Marina 08/2010; 74:569-575. DOI:10.3989/scimar.2010.74n3569 · 1.14 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper we addressed the phylogeographical genetic structure of the economically important red shrimp, Aristeus antennatus (Crustacea, Aristeidae) in the Western Mediterranean. Partial mitochondrial regions of the cytochrome c oxidase subunit I (514 bp) and ribosomal 16S subunit (547 bp) were sequenced in 137 individuals collected at three localities: Catalan Sea, Ligurian Sea and the southern Tyrrhenian Sea. Values of haplotypic diversity were h = 0.552-0.724, whereas those for nucleotide diversity were pi = 0.0012-0.0026. Among-sample genetic diversity was not significant and no geographical patterns in the distribution of haplotypes were apparent. Results of the present study are consistent with a past population expansion that occurred <2,000 years ago. Despite the current fishing pressure, genetic variability appears to be sufficiently high to keep A. antennatus populations stable over time. Dispersal-related life history traits may account for the shallow genetic structure. Our results are not in contrast with the hypothesis of sustainability of Western Mediterranean red shrimp fisheries predicted on the basis of previously obtained biological results.
[Show abstract][Hide abstract] ABSTRACT: Conservative morphological characters make identification of mullet species difficult. As a consequence, cosmopolitan distribution of Mugil cephalus is currently under discussion. In order to clarify the controversy regarding the taxonomic status of the southern Atlantic American mullet M. platanus, in relation to Mugil cephalus, a comprehensive analysis is presented using sequences of the mitochondrial gene cytochrome b, landmark‐based morphometry and meristic data. The interlandmark distances showed differentiation between individuals of M. platanus and M. cephalus analyzed. Variables, representing the height at different levels of the longitudinal axis of the body, exposed that M. platanus has more robust middle and caudal segments of the body, in a lateral view, with respect to M. cephalus. Transversal series scales have not been useful for the identification of species. Lateral series scales seem to be useful to differentiate species, but taking into account that range showed an overlapped gradual variation. Genetic distance obtained between species shows a typical intrageneric level comparison. Two clear phylogroups have been detected indicating a high degree of genetic isolation between both species. Recognition of M. platanus as valid allopatric species is suggested.
Italian Journal of Zoology 09/2008; 75(3-3):319-325. DOI:10.1080/11250000801886254 · 0.79 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract – Conservation of genetic diversity within species requires effective management techniques. To study the spatial structure of the killifish Aphanius iberus and to improve ongoing conservation practices, we used genetic approaches to assess the genetic structure of this endemic Iberian species. Twenty locations were analysed by allozyme electrophoresis and allelic variation was detected at 11 of 17 loci examined. Results of our study enabled us to redefine its conservation policy based on Operational Conservation Units (OCUs), which were proposed in 1996. The new OCUs recognise the genetic isolation of some marshland populations (FST = 0.247) and incorporate reintroductions that occurred over the last 10 years. We also propose that the status of A. iberus in the International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species be changed from data deficient to endangered. Our work exemplifies how temporal genetic monitoring of populations can be a powerful tool to improve conservation programmes.
Ecology of Freshwater Fish 05/2007; 16(2):257 - 266. DOI:10.1111/j.1600-0633.2006.00217.x · 1.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A survey described genetically encoded enzyme variation in 197 adult Argentinian hake, Merhccius hubhsi, collected from 10 sample sites on the Argentinian continental shelf. Four of 11 muscle enzyme loci were polymorphic (PCM*, G3PDH*, EST-1* and EST-2*). Genotypes showed no significant difference between males and females. Only one of 37 tests of departure from Hardy-Weinberg equilibrium showed a significant difference. The allele frequency data were tested for genetic heterogeneity among locations. The overall significance of the total samples and among those from Patagonia Central was primarily due to heterogeneity at the EST-1* locus. The implications of these findings in a population structure context are discussed.
Journal of Fish Biology 01/2006; 39(sA):53 - 59. DOI:10.1111/j.1095-8649.1991.tb05067.x · 1.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Bonito Sarda sarda samples collected in three areas from the Mediterranean Sea exhibited considerable genetic heterogeneity over all locations. This provided preliminary evidence for two different groups of bonito, one for the Ligurian and the Ionian Seas and the other for the Aegean Sea.
Journal of Fish Biology 04/2005; 59(1):169 - 174. DOI:10.1111/j.1095-8649.2001.tb02347.x · 1.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: 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.
[Show abstract][Hide abstract] ABSTRACT: Nine samples of swordfish from different Mediterranean areas plus a sample obtained in Atlantic waters adjacent to the Strait of Gibraltar were examined for temporal and spatial heterogeneity using allozyme analysis. Only two out of 38 loci (IDHP-2* and LDH-3*) were polymorphic based on a frequency of less than 0.95 in one or more samples. Both polymorphism and heterozygosity revealed a low genetic variability for swordfish in comparison with other pelagic species. No heterogeneity due to differences between age groups was observed for those samples including juvenile and adult specimens. The lack of temporal or spatial heterogeneity found in this study is consistent with a single population of swordfish in the Mediterranean Sea and adjacent waters of the Atlantic Ocean.
Journal of Experimental Marine Biology and Ecology 09/2002; 276(1-2-276):19-29. DOI:10.1016/S0022-0981(02)00245-9 · 1.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The systematic status and the evolutionary biology of chub mackerel (Scomber japonicus) in the South West Atlantic Ocean is confusing with an unknown degree of genetic differentiation and reproductive isolation between units. Simultaneous genetic and morphologic analyses were made on 227 fish collected from two areas of the South West Atlantic Ocean and one from the Mediterranean Sea. The genetic analysis was based on 36 protein-coding loci, 16 of which were variable. The morphologic analyses include six morphometric length measurements and a meristic character. Correspondence between genetic and morphologic variability patterns indicates isolated Mediterranean and Southwest Atlantic subgroups of S. japonicus and, less clearly, possible additional divergence in two regional stocks within the latter group. The most conservative approach to management is to manage the stocks independently of one another.
Journal of Experimental Marine Biology and Ecology 11/2000; 253(1-253):63-74. DOI:10.1016/S0022-0981(00)00244-6 · 1.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Genetic data from nine species of Merluccius (Euro-African species merluccius, capensis, paradoxus, polli, senegalensis; American species bilinearis, productus, hubbsi, australis) from 21 informative allozyme loci provided insights into the phylogenetic and biogeographical relationships within the genus. The highest values of polymorphic loci and mean heterozygosity occur in the four American species. These values are consistent with large population sizes during speciation (through vicariant processes), and continuing through to the present. Conversely, the lower values of Euro-African species are consistent with bottlenecks occurring during or subsequent to speciation. Euro-African and American species formed two distinct clades. In the former group, merluccius, capensis and senegalensis clustered together as the most derived species, with distinct relationships between polli and paradoxus from an earlier divergence. Similarly, productus, australis and hubbsi clustered closely as the most derived American species, clearly diverging from the more ancestral bilinearis. Analyses including comparative data previously published for M. gayi indicated a close pairing to hubbsi. The data support a north-west Atlantic origin of the genus with unsampled M. albidus of broad Caribbean distribution proposed as the most primitive extant species.
[Show abstract][Hide abstract] ABSTRACT: Genetic data from nine species of Merluccius (Euro–African species merluccius, capensis, paradoxus, polli, senegalensis; American species bilinearis, productus, hubbsi, australis) from 21 informative allozyme loci provided insights into the phylogenetic and biogeographical relationships within the genus. The highest values of polymorphic loci and mean heterozygosity occur in the four American species. These values are consistent with large population sizes during speciation (through vicariant processes), and continuing through to the present. Conversely, the lower values of Euro–African species are consistent with bottlenecks occurring during or subsequent to speciation. Euro–African and American species formed two distinct clades. In the former group, merluccius, capensis and senegalensis clustered together as the most derived species, with distinct relationships between polli and paradoxus from an earlier divergence. Similarly, productus, australis and hubbsi clustered closely as the most derived American species, clearly diverging from the more ancestral bilinearis. Analyses including comparative data previously published for M. gayi indicated a close pairing to hubbsi. The data support a north-west Atlantic origin of the genus with unsampled M. albidus of broad Caribbean distribution proposed as the most primitive extant species.
[Show abstract][Hide abstract] ABSTRACT: Allozyme analysis of tissue samples of 910 European hake Merluccius merluccius from six North Atlantic Ocean and four Mediterranean Sea locations revealed polymorphism at 21 out of 34 protein-coding loci examined. A major subdivision between Atlantic and Mediterranean collections (mean Nei's genetic distance within regions 0.005; between regions 0.014) was particularly evident from allelic differences at the GAPDH-1* and GR-2* loci. Further population subdivision was indicated within both regions, and gene flow from adjacent Atlantic to proximal Mediterranean populations was suggested by allele frequencies and relevant oceanographic and geological information. The data support present management based on distinct Atlantic and Mediterranean populations and indicate that the population structure within the Atlantic is more complex than the discrete northern and southern stocks proposed by ICES.
[Show abstract][Hide abstract] ABSTRACT: Eleven samples of rose shrimp (Aristeus antennatus) from different areas of the Mediterranean Sea and adjacent Atlantic waters were subjected to morphometric and electrophoretic analyses. The object was to characterize possible population differences that would account for previously reported differences in behavioural patterns observed in commercial fishing activity. Genetic analysis of 27 enzyme systems yielded only fifteen useful loci of which fibre had allele variants, but only two of them were polymorphic within 95%. Morphometric analysis of nine body and appendage measurements revealed significant differences between sampling sites in scaphocerite length, uropodal length, and the length of the articles on the third walking leg. The samples analysed genetically could not be differentiated, but morphological differences were compared between different hydrographic regions of the Mediterranean Basin.
Journal of Experimental Marine Biology and Ecology 03/1998; 221(1-221):131-144. DOI:10.1016/S0022-0981(97)00119-6 · 1.87 Impact Factor