Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Myrmecophytes offer plant-ants a nesting place in exchange for protection from their enemies, particularly defoliators. These obligate ant-plant mutualisms are common model systems for studying factors that allow horizontally transmitted mutualisms to persist since parasites of ant-myrmecophyte mutualisms exploit the rewards provided by host plants whilst providing no protection in return. In pioneer formations in French Guiana, Azteca alfari and Azteca ovaticeps are known to be mutualists of myrmecophytic Cecropia (Cecropia ants). Here, we show that Azteca andreae, whose colonies build carton nests on myrmecophytic Cecropia, is not a parasite of Azteca-Cecropia mutualisms nor is it a temporary social parasite of A. alfari; it is, however, a temporary social parasite of A. ovaticeps. Contrarily to the two mutualistic Azteca species that are only occasional predators feeding mostly on hemipteran honeydew and food bodies provided by the host trees, A. andreae workers, which also attend hemipterans, do not exploit the food bodies. Rather, they employ an effective hunting technique where the leaf margins are fringed with ambushing workers, waiting for insects to alight. As a result, the host trees' fitness is not affected as A. andreae colonies protect their foliage better than do mutualistic Azteca species resulting in greater fruit production. Yet, contrarily to mutualistic Azteca, when host tree development does not keep pace with colony growth, A. andreae workers forage on surrounding plants; the colonies can even move to a non-Cecropia tree.
ISSN: 0028-1042

hal-00818203
https://hal.archives-ouvertes.fr/hal-00818203
DOI : 10.1007/s00114-010-0710-y
PUBMED : 20730522

Éditeur(s) : EDP Sciences
Résumé : For centuries, several species of prawns and crabs have been raised from wild-caught juveniles in coastal brackish-water fish ponds in various countries of south east Asia. The Indonesian "tambaks" are well known examples of such traditional practices. In western countries, since the turn of the century, advances of marine biology and fast increase of marine fisheries enabled the development of large-scale production and release of larval stages of American and European lobsters in a fruitless attempt to restock natural populations. After the Second World War, the increasing demand for crustaceans in United States and Japan was satisfied by opening new prawn fisheries all over the world. A major breakthrough was achieved with the development of hatchery technologies for the penaeid prawn Penaeus japonicus (Hudinaga, 1942 in Japan) and the caridean prawn Macrobrachium rosenbergii (Ling, 1969 in Malaysia), which occurred during the first decades of the second half of this century. Together with the increasing market demand in developed countries for sea food, this led to a considerable interest of both public agencies and private investors in marine shrimp and prawn culture. In western countries, a large number of pioneering commercial ventures, often based on assumptions not scientifically founded, failed. Nevertheless, the aquaculture production of prawns mainly based on wild-caught juveniles increased in South-East Asia and Central America during the 1980s. This overall positive trend should not hide important failures which occurred at a local scale, such as the Taiwanese crisis of 1988 due principally to environmental degradation, resulting in severe disease problems and a near collapse of the farming activity. Following the early period of hatchery technology development, the major scientific achievements were related to food requirements and formulation of compound diets for larvae, juveniles and adults and to a better knowledge of diseases caused by bacteria and several viruses which have been identified from hatcheries and intensive farming ponds. Additional new technological advances have emerged from recent research in the fields of physiology (endocrinology) and genetics. By far, the major part of the world production of marine crustaceans relies on penaeid prawns and, to a lesser extent, on Macrobrachium species. However, some other species of marine crustaceans have potential for aquaculture. The economic aspects of marine crustacean aquaculture should be considered together with those of the fishing industry: market prices are rather similar, depending on the quality of the product. The balance between market demand and production is an important constraint which, in turn, establishes the success of prawn farming. Since the early 1980s, crustacean aquaculture has increased tremendously in both Asia and America: the world production for 1991 approximated 700,000 tons, with more than 600,000 tons from penaeid prawn culture.
Pendant des siècles, quelques espèces de crevettes et de crabes ont été élevées à partir d'individus juvéniles capturés dans le milieu naturel, dans des bassins à poissons d'eau saumâtre de différents pays d'Asie du Sud-Est. Les « tambaks » indonésiens sont des exemples bien connus de ces pratiques traditionnelles. Dans les pays occidentaux, depuis le début du siècle, les progrès réalisés en biologie marine et la croissance rapide des pêches maritimes ont permis le développement de la production à grande échelle de stades larvaires des homards européen et américain, dans une vaine tentative de reconstitution des stocks naturels. Après la Seconde Guerre mondiale, la demande croissante des Etats-Unis et du Japon a été satisfaite par l'ouverture de nouvelles pêcheries de crevettes dans l'océan mondial. Un progrès décisif a été réalisé avec la mise au point des techniques d'écloserie pour la crevette Pénaeidé Penaeus juponicus (Hudinaga, 1942 au Japon) et la crevette Caridé Macrobrachium rosenbergii (Ling, 1969 en Malaisie), qui sont apparues au cours des premières décennies de la seconde moitié de ce siècle. Parallèlement à la demande croissante du marché des pays développés pour les produits de la mer, ce résultat s'est traduit par un intérêt considérable porté à l'élevage des crevettes marines de la part des institutions de recherche et des investisseurs. Dans les pays occidentaux, un grand nombre de tentatives d'élevage commerciales, fondées sur des considérations non scientifiquement établies, ont échoué. Néanmoins, la production aquacole de crevettes reposant sur la capture d'animaux juvéniles dans la nature, s'est développée en Asie du Sud-Est et en Amérique Centrale au cours des années 1980. Cette tendance globalement positive ne doit pas dissimuler les faillites importantes qui se sont produites à l'échelle locale, comme la crise des élevages de Taiwan en 1988, causée principalement par une dégradation de l'environnement, entraînant l'apparition de problèmes pathologiques sévères et une disparition presque totale de l'activité d'élevage. Après la période pionnière du développement de la technologie d'écloserie, les principaux acquis scientifiques concernent les besoins alimentaires et la formulation d'aliments composés pour les larves, les jeunes et les adultes, et une meilleure connaissance des maladies bactériennes et virales qui interviennent dans les écloseries et les fermes d'élevage intensif. De nouveaux progrès techniques complémentaires ont vu le jour à la suite de recherches dans les domaines de la physiologie (endocrinologie) et de la génétique. De loin, la majeure partie de la production mondiale de Crustacés marins repose sur les crevettes Pénaeidés et, dans une moindre mesure, sur des espèces de Macrobrachium. Cependant, quelques autres espèces de Crustacés marins intéressent potentiellement l'aquaculture. Les aspects économiques de l'aquaculture de crustacés marins doivent être considérés avec ceux de l'industrie des pêches maritimes : les prix du marché sont à peu près les mêmes, et dépendent de la qualité du produit. Le rapport entre la demande du marché et la production est une contrainte importante qui à son tour, détermine les conditions du succès de l'élevage de crevettes. Depuis le début des années 1980, l'aquaculture de crustacés a augmenté considérablement en Asie et en Amérique : la production mondiale pour 1991 avoisine 700 000 tonnes, avec plus de 600 000 tonnes provenant des élevages de crevettes Pénaeidés.
Aquatic Living Resources (0990-7440) (EDP Sciences), 1993-10 , Vol. 6 , N. 4 , P. 319-329

Droits : IFREMER-Gauthier-Villars, 1993
http://archimer.ifremer.fr/doc/00190/30119/28587.pdf
DOI:10.1051/alr:1993033
http://archimer.ifremer.fr/doc/00190/30119/

Éditeur(s) : HAL CCSD Wiley
Résumé : [b]Aim[/b][br/] [br/] The phylogeographical history of Neotropical species can be difficult to reconstruct because of superimposed Neogene and Quaternary histories, and because of taxonomic uncertainty. We analysed range-wide genetic diversity in a widespread pioneer tree species, Jacaranda copaia (Aubl.) D. Don, to characterize phylogeographical structure, date the evolutionary relationships among lineages, and evaluate the role of dispersal and vicariance in establishing the present geographical range.[br/] [br/] [br/] [b]Location[/b][br/] [br/] Guiana Shield; central, southern and western Amazon Basin; Chocó region; Central America.[br/] [br/] [br/] [b]Methods[/b][br/] [br/] We analysed nine nuclear simple sequence repeat loci (nuSSR), eight chloroplast SSRs (cpSSR), and two cpDNA intergenic sequences in 341 adult trees. Genetic differentiation at nuSSRs was inferred using Bayesian clustering. Dating of chloroplast lineage divergence was obtained using a range of published mutation rates and Bayesian coalescence analyses. Population divergence dating was performed using an isolation-with-migration model for eight loci (one cp sequence and seven nuSSRs).[br/] [br/] [br/] [b]Results[/b][br/] [br/] Nuclear SSR variation identified three geographically overlapping clusters (nu-1, nu-2, nu-3). Twelve cpDNA haplotypes were clustered into two haplogroups (cp-1, cp-2) with the central Amazon harbouring the highest diversity. Molecular dating analysis suggests that cpDNA haplotype diversification started around the end of the Pliocene (2.61 Ma on average), whereas population divergence was more recent and occurred during the mid-Quaternary (point estimates between 357 and 436 ka).[br/] [br/] [br/] [b]Main conclusions[/b][br/] [br/] The genetic variation of J. copaia in the Neotropics was shaped mainly by Pleistocene events. Chloroplast diversity did not display the expected cis/trans Andean disjunction, indicating recent dispersal. Nuclear variation revealed that separate regions share a recent history, with a centre of diversity in the central Amazon Basin. The geographical pattern of diversity is congruent with the distribution of the two subspecies, J. copaia copaia and J. copaia spectabilis, and evidence of nuSSR admixture between the two taxa supports their classification as subspecies.
ISSN: 0305-0270

hal-01032410
https://hal.archives-ouvertes.fr/hal-01032410
DOI : 10.1111/j.1365-2699.2012.02797.x