Temporal and spatial genetic differentiation in the crab Liocarcinus depurator across the Atlantic-Mediterranean transition.

Spatial genetic studies often require sampling broadly separated areas, difficult to access simultaneously. Although comparing localities surveyed at different time periods might result in spurious genetic differentiation, there is a general believe on the stability of genetic structure through time, particularly if sampled localities are isolated or very distant. By analysing spatial and temporal genetic differentiation of the portunid crab Liocarcinus depurator we assessed the contribution of historical and contemporary processes on population connectivity patterns across three main oceanographic discontinuities along the Atlantic-Mediterranean transition: Gibraltar Strait, Almeria-Oran Front and Ibiza Channel. A partial fragment of the cytochrome oxidase I gene was sequenced in 366 individuals collected from localities at both sides of each discontinuity during three time periods. Although localities showed genetic fluctuations through time, a significant gradient was detected along the coast for all sampling periods. Significant inter-annual differences identified within the Alicante area, north of the Almeria-Oran Front, were associated with shifts in the relative contribution of Atlantic and Mediterranean water masses. The persistence of a clinal pattern in the Atlantic-Mediterranean transition area together with local fluctuations suggests a complex balance of dispersal and selection.

Species of the genus Galathea Fabricius, 1793 (Crustacea, Decapoda, Galatheidae) from the Indian and Pacific Oceans, with descriptions of 92 new species.

The genus Galathea is one of the most speciose and unwieldy groups in the family Galatheidae. The examination of more than 9000 specimens of 144 species collected in the Indian and Pacific Oceans using morphological and molecular characters, has revealed the existence of 92 new species. The specimens examined during this study were obtained by various French expeditions supplemented by other collections from various sources, and including the type specimens of some previously described species. Most of the new species are distinguished by subtle but constant morphological differences, which are in agreement with molecular divergences of the mitochondrial markers COI and/or 16S rRNA. Here, we describe and illustrate the new species and redescribe some previously described species for which earlier accounts are not sufficiently detailed for modern standards. Furthermore we include a dichotomous identification key to all species in the genus from the Indian and Pacific Oceans. 

A new genus and some new species of the genus Lauriea Baba, 1971 (Crustacea, Decapoda, Galatheidae) from the Pacific and Indian Oceans, using molecular and morphological characters.

The genus Lauriea belongs to the family Galatheidae and is easily differentiated from other genera of the family by the endopod of the uropod being much wider than long and the dactyli of the walking legs being curved and strongly biunguiculate. Examination of many specimens collected during recent expeditions from Madagascar to French Polynesia and using morphological and molecular data revealed the existence of six species, five of them new, that are genetically distinct yet morphologically very similar. Furthermore, another new species, having a triunguiculate P2-4 dactyli, represents a new genus, Triodonthea.

Phylogeographic patterns of decapod crustaceans at the Atlantic-Mediterranean transition.

Comparative multispecies studies allow contrasting the effect of past and present oceanographic processes on phylogeographic patterns. In the present study, a fragment of the COI gene was analyzed in seven decapod crustacean species from five families and with different bathymetric distributions. A total of 769 individuals were sampled along the Atlantic-Mediterranean transition area in order to test the effect of three putative barriers to gene flow: Strait of Gibraltar, Almeria-Oran Front and Ibiza Channel. A significant effect of the Strait of Gibraltar was found in the crabs Liocarcinus depurator and Macropipus tuberculatus. The Ibiza Channel had a significant effect for L. depurator. However, the Almeria-Oran front was not found to have a significant effect on any of the studied species. Higher levels of population structure were found in shallow-water species, although the number of species sampled should be increased to obtain a conclusive pattern. The haplotypes within the different species coalesced at times that could be related with past climatic events occurring before, during and after the last glacial maximum. Given the large diversity of phylogeographic patterns obtained within decapods, it is concluded that both historical and contemporary processes (marine current patterns, bathymetry and life-history traits) shape the phylogeographic patterns of these crustaceans.

Spatiotemporal genetic differentiation of Cuban natural populations of the pink shrimp Farfantepenaeus notialis.

We analyzed the spatiotemporal genetic structure of Farfantepenaeus notialis populations using five microsatellites loci in order to understand the influence of natural events such as hurricanes on the genetic drift/migration balance as the main cause for the variation of allele frequencies over time. The results were compared with the previous ones obtained from allozymes and mtDNA. High and stable genetic diversity levels (He=0.879+/-0.0015) were found over eight years for the populations that inhabit the south Cuban platform, however significant changes of allele frequencies were detected over time. The F(ST) estimates, albeit low, revealed significant differences among populations inside the Ana Maria Gulf for 1995 but not for the 1999 and 2003 samples. The F(ST), AMOVA and the genetic distance analysis revealed the instability of the genetic structure over time in accordance with allozymes results. The correspondence of the microsatellite results with those obtained from allozymes confirm the effects of migration enhanced by natural events as the main cause of the temporal variation of allele frequencies. The genetic drift effect was discarded through the evaluation of Ne and the M ratio, while natural selection effects were rejected because of the lowest probability of microsatellite loci being under selective pressures. The microsatellite data are also consistent with the results obtained with mtDNA in detecting significant and persistent genetic differences between the Gulfs of Ana María and Batabanó for the years 1995 and 2003.

Temporal variation of the population structure and genetic diversity of Farfantepenaeus notialis assessed by allozyme loci.

Population genetic studies carried out on penaeid shrimps have disclosed different patterns of population subdivision, revealing new aspects of shrimp biology as well as the effects of historical contingency molding those patterns. However, the stability of observed allele frequencies over time still remains untested. The objective of this article is to show the analysis of the temporal variation of allozymes in a shrimp species inhabiting Cuba which proves that the genetic structure of this species could significantly change in time. The study involves four populations of Farfantepenaeus notialis sampled in a period of 8 years. The significant statistics obtained from partitions observed in 1995 were not detected in 2003 (as suggested by AMOVA and F(ST)), whereas temporal genetic differentiation and heterozygosity became highly significant. The results strongly suggest that the effect of migrations could be the cause for the loss of F. notialis genetic structure in 2003. It is therefore imperative to call attention on the vulnerability of these populations when facing unstable environmental and habitat conditions.

Microsátelites del camarón blanco litopenaeus shmitti (Crustacea, Decapoda) / Microsatellites from the white shrimp litopenaeus chmitti (Crustacea, Dacapoda)

A partir de una genoteca de ADN construida con insertos entre 300 pb y 700 pb, se identificaron secuencias microsátelites de litopenaeus schmitti, especie cubana de camarón utilizada en la acuicultura. Las 910 colonias que se obtuvieron fueron analizadas en busca de repeticiones y resultaron positivos 114 clones de los cuales 106 lo fueron para los oligonucléotidos (TC)15, (TG)15 y (TAA)15 y 8 para el oligonucléotido (GTC)15...(AU)