Comunicación corta. Dormición secundaria en Diplotaxis erucoides: una posible estrategia adaptativa como mala hierba anual

The germination of stored Diplotaxis erucoides seed was studied under controlled conditions of temperature and light by conducting germination tests over three years after collection. The D. erucoides seed was not dormant at harvest, but secondary dormancy appeared during storage as indicated by reduced germination 12 months after collection (from 92% down to 39%). This could be overcome by prolonged storage or by the use of gibberellic acid. Such shifts between dormancy and non-dormancy can be interpreted in terms of the soil seed bank dynamics in relation to intraspecific competition and/or with its adaptation as an annual weed in periodically disturbed soil in cultivated areas.Se estudió la evolución de la germinación/dormición de semillas de Diplotaxis erucoides mediante ensayos periódicos en condiciones controladas (temperatura y luz), durante tres años desde el momento de su recolección. Las semillas recién recolectadas no presentaron dormición, pero a los 12 meses apareció una dormición secundaria (la germinación disminuyó de un 92% a un 32%), desapareciendo posteriormente durante el almacenamiento o mediante aplicaciones exógenas de ácido giberélico. Los cambios entre estado no durmiente y durmiente de las semillas se interpretan como una dinámica de las semillas en el banco del suelo, como posible estrategia relacionada con la competición intraespecífica y su adaptación como mala hierba anual

Genetic background of Galician wreckfish Polyprion americanus broodstocks

The wreckfish Polyprion americanus is a long-living pelagic fish with a demersal adult phase that shows an antitropical distribution. In the Eastern Atlantic, juvenile and adult wreckfish are found off from the Norwegian coast to Southern Africa including shallow portions of the Mid-Atlantic ridge and associated islands (Macaronesian Islands) and the Mediterranean Sea (Sedberry et al. 1999). This species is a promising candidate for aquaculture and consequently it has recently been brought to Galician hatcheries for domestication (Peleteiro and Rodríguez, 2012). It is well known that domestication and management of hatchery stocks require an adequate strategy for the initial broodstock foundation and its further reproductive management. Therefore the combination of genetic markers with classic domestication strategies seems to be a useful approach to skip both genetic drift and consanguineous adverse effects. New microsatellite markers have been isolated for ecumenical tasks in this species and applied them to assess the genetic status of the four wreckfish stocks being harvested in Galician hatcheries as compared to the genetic diversity present in its source population from the Eastern Atlantic. Additionally, we aimed to predict the success of different reproductive strategies upon the in silico simulation of F1 and F2 progenies from each stock

First-generation genetic drift and inbreeding risk in hatchery stocks of the wreckfish Polyprion americanus

The wreckfish Polyprion americanus is a component of directed and admixed species fisheries throughout its world range and has recently been identified for its aquaculture potential. Several wreckfish broodstocks were founded in Galician hatcheries in the last decade and are now approaching maturity. The combination of genetic markers with classic domestication strategies is a pertinent approach to preserve genetic variation and to slow down consanguineous-derived adverse effects. Genetic data from microsatellites used to characterize four Galician wreckfish stocks provide evidence of both, a significant interstock differentiation (7.60%) and a pronounced loss of allele diversity (26%) in 80% of the stocks. Such artificial sub-structuring linked to the erosion of gene diversity is most likely caused by sampling drift that stepped up from the North Atlantic population. Computer simulation of relatedness helps to appraise alternate breeding protocols to avoid uncontrolled inbreeding within stocks. We show that under a fixed number of breeders and a sex balanced contribution, two protocols consisting on randommatingamong broodstocks (ΔRxy=2.21%) or enhancedwith a wild sample (ΔRxy= 0.97%), are far more advantageous strategies to slow inbreeding in F1 and F2 than breeding protocols within stock (ΔRxy= 6.6%).Versión del edito

On the taxonomy and distribution of Callinectes Stimpson (Crustacea, Decapoda, Portunidae) in Rio Grande do Norte

A faunistic survey of the species of Callinectes Stimpson, 1871 carried out in the coastal and estuarine regions of the State of Rio Grande do Norte yielded five species: C. bocourti A. Milne Edwards, 1879; C. danae Smith, 1869; C. exasperatus (Gerstaecker, 1856); C. larvatus Ordway, 1863 and C. ornatus Ordway, 1863. Specimens examined consist of those collected on a monthly basis from three fixed stations within the estuary of Potengi, Natal during a period of two years and those obtained from other localities. Among the species occuring in the region, C. danae is more abundant and has a wider range of tolerance of salinity while C. larvatus is restricted to the marine habitat. Though C. danae sustains important artisan fishery, C. bocourti of large size also contribute to the fishery

Combining genetic markers with classic domestication strategies for the wreckfish (Polyprion americanus): A candidate species with high aquaculture potential

The wreckfish Polyprion americanus is a long-living pelagic fish with a demersal adult phase that shows an antitropical distribution. In the eastern Atlantic, juvenile and adult wreckfish are found off the Norwegian coast along shallow portions of the Mid-Atlantic ridge and associated islands (Macaronesian Islands), and along northern and southern Africa including the Mediterranean. This species is a component of directed and admixed species fisheries throughout its range and has recently been focused for its large aquaculture potential: adults reach 100cm in length, show low natural mortality rates and a large longevity. Therefore it is one of the most promising species for aquaculture and consequently it has recently been brought to Galician hatcheries for taming. These good priors for aquaculture are however devoid of useful information on its whole life cycle, taxonomic classification and genetic status. It is well known that domestication and management of hatchery stocks require an adequate strategy for the initial broodstock foundation and its further reproductive management. Therefore the combination of genetic markers with classic domestication strategies seems to be a useful approach to skip consanguineous adverse effects and genetic drift. In this study we have first isolated new microsatellite markers for ecumenical tasks in this species. Then we have applied those markers to assess the genetic status of the four wreckfish stocks being harvested in n Galicia hatcheries as compared to the genetic diversity present in its source population from the Eastern Atlantic. Since the first successful spawning of wreckfish in captivity has recently been achieved in a Galicia hatchery, we provide here the first assessment on the reproductive structure of such stock, based on the genetic assignment of its progenies. Preliminary results show a significant genetic differentiation (2.25% of the whole inter-stock genetic variance) among broodstocks from the four Galician hatcheries and a pronounced loss of diversity in two of them regarding the genetic richness of the wild source population

Combinación de estrategias clásicas y marcadores genéticos para la domesticación de la cherna (Polyprion americanus): una especie candidata de alto potencial acuícola

La chema, Polyprion americanus, es un pez pelágico muy longevo, con una lase adulta demersal que muestra una distribución antitropical. Está considerada como una de las especies más prometedoras para la acuicuñura y, en consecuencia, se han comenzado a domesticar 5 stocks en Galicia. A pesar de las buenas condiciones para la acuicultura no existe suliciente inlormación sobre su ciclo de vida completo, su clasificación taxonómica y estatus genético. Es sabido que se requiere una estrategia adecuada para la lundación del stock de reproductores y su manejo reproductivo, y por ello en este estudio hemos aislado nuevos marcadores microsatélites para tareas ecuménicas en esta especie. Estos marcadores se han aplicado a la evaluación de la diversidad genética de las poblaciones de chema en piscifactorías gallegas y se han oomparaoo con la diversidad genética de su población de origen en el Atíánneo oriental. Como el primer desove de chema en cautiverio se ha obtenido recientemente en Galicia, en este trabajo presentamos la primera evaluación de la estructura reproductiva basada en la asignación de progenies. Los resultados muestran una diferenciación genética signifocativa (2.25 de la varianza genética inter-stock) entre los 4 stocks de reproductores analizados en este trabajo y una pronunciada pérdida de diversidad en dos de ellas con respecto a la riqueza genética de la población de origen.The wreckfish Polyprion americanus is a long-living pelagic fish wilh a demersal adult phase Ihat shows an antitropical distribution. Therelore n~ one 01 Ihe most promising species tor aquacuture and consequenHy tt has recenHy been brought to Galician hatcheries lor taming. These good priors lor aquacuhure are however devoid 01 uselul inlormation on its whole life cycle, taxonomic classifocation and genetic status. It is well known Ihat domestication and management 01 hatchery stocks require an adequate strategy lor Ihe initial broodstock loundation and its further reproductive management. In this study we have lirst isolated new microsatelltte rnarkers lor ecumenical tasks in Ihis species. Then we have appIied Ihose rnarkers to assess Ihe genetic status ollhe lour wreckfish stocks being harvested in Galician hatcheries as companed to Ihe genetic diversity present in its source population Irom Ihe Eastem Mantic. Since Ihe first successful spawning 01 wreckfish in captivtty has recenHy been achieved ~ a Galician hatchery, we provide here Ihe first assessment on Ihe reproductive structure 01 such stock, based on Ihe genetic assignmenl of iIs progenies. Preliminary resuíts show a significant genetic differentiation (2.25% 01 the whole inter-stock genetic variance) among broodstocks from the lour Galician hatcheries and a pronounced loss 01 diversity in twoofthem regarding the genetic richness ofthe wild source population