26 research outputs found

    Border Insecurity: Reading Transnational Environments in Jim Lynch’s Border Songs

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    This article applies an eco-critical approach to contemporary American fiction about the Canada-US border, examining Jim Lynch’s portrayal of the British Columbia-Washington borderlands in his 2009 novel Border Songs. It argues that studying transnational environmental actors in border texts—in this case, marijuana, human migrants, and migratory birds—helps illuminate the contingency of political boundaries, problems of scale, and discourses of risk and security in cross-border regions after 9/11. Further, it suggests that widening the analysis of trans-border activity to include environmental phenomena productively troubles concepts of nature and regional belonging in an era of climate change and economic globalization. Cet article propose une lecture Ă©cocritique de la fiction Ă©tatsunienne contemporaine portant sur la frontiĂšre entre le Canada et les États-Unis, en Ă©tudiant le portrait donnĂ© par Jim Lynch de la rĂ©gion frontaliĂšre entre la Colombie-Britannique et Washington dans son roman Border Songs, paru en 2009. L’article soutient que l’étude, dans les textes sur la frontiĂšre, des acteurs environnementaux transnationaux – dans ce cas-ci, la marijuana, les migrants humains et les oiseaux migratoires – jette un jour nouveau sur la contingence des limites territoriales politiques, des problĂšmes d’échelle et des discours sur le risque et la sĂ©curitĂ© des rĂ©gions transfrontaliĂšres aprĂšs les Ă©vĂšnements du 11 septembre 2001. Il suggĂšre Ă©galement qu’en Ă©largissant l’analyse de l’activitĂ© transfrontaliĂšre pour y inclure les phĂ©nomĂšnes environnementaux, on brouille de façon productive les concepts de nature et d’appartenance rĂ©gionale d’une Ă©poque marquĂ©e par les changements climatiques et la mondialisation de l’économie

    Climate mediates the effects of disturbance on ant assemblage structure

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    Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about howclimate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages, we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effectwas manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 98C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk. © 2015 The Author(s) Published by the Royal Society. All rights reserved

    Genomic investigations of unexplained acute hepatitis in children

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    Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK1. Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

    Native communities of leaf-litter ant communities in natural forests of French Guiana, and impact of forest conversion in monocultural tree plantations

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    Les fourmis sont des organismes cibles appropriĂ©s pour les Ă©tudes environnementales. Au cours de notre Ă©tude, nous nous sommes focalisĂ©s sur les fourmis de la litiĂšre via l'application de deux mĂ©thodes de rĂ©colte complĂ©mentaires selon le protocole all (ants of leaf litter). Dans les forĂȘts naturelles de Guyane française, l'hĂ©tĂ©rogĂ©nĂ©itĂ© environnementale et les perturbations structurent les communautĂ©s de fourmis de la litiĂšre en influençant la richesse, la diversitĂ©, l'abondance et la densitĂ© en espĂšces ainsi que les compositions taxonomique et fonctionnelle. Chaque type de formation vĂ©gĂ©tale possĂšde une communautĂ© spĂ©cifique. La fragmentation et la conversion des forĂȘts en plantations ont entrainĂ© une altĂ©ration plus ou moins profonde des communautĂ©s; cette variabilitĂ© est fonction du type d’agriculture et des espĂšces d'essences cultivĂ©es. Bien que l'altĂ©ration des communautĂ©s se soit rĂ©vĂ©lĂ©e maximale dans la plupart des monocultures, les plantations de cacaoyers ont un potentiel de conservation rĂ©el. Enfin, dans un contexte ou il est urgent de simplifier l'intĂ©gration des arthropodes dans les Ă©tudes de conservation, de contrĂŽle et de suivi de la santĂ© des Ă©cosystĂšmes terrestres, la mĂ©thode des rĂ©seaux de neurones est apparue comme un outil puissant pour mettre en Ă©vidence et analyser les patrons des communautĂ©s de fourmis.Ants are reliable and relevant target organisms for environmental surveys. In our study, we focused on litter-dwelling ants through the use of two complementary sampling methods that were implemented according to the ants of leaf litter (all) protocol. In pristine forests of french guiana, leaf-litter ant communities are structured by environmental heterogeneity and natural perturbations - which influence species richness, diversity, abundance and density, as well as taxonomic and functional composition. This results in habitat-specific communities for each vegetal formation. Forest fragmentation and conversion into monocultures have led to a more or less deep alteration of the ant communities; this variability depends on the type of agricultural system and cultivated tree species. Although the intensity of community alteration peaked in tree monocultures, cocoa plantation exhibited a real potential for native species conservation. Finally, in the current context where simplifying the integration of arthropods into conservation programs as well as into surveys designed to monitor and manage the environment is critical, the use of neural networks appears to be a powerful tool for reliably highlighting and analyzing ant communities patterns

    CommunautĂ©s natives des fourmis de la litiĂšre en forĂȘts naturelles de Guyane française et impact de la conversion forestiĂšre en plantations monospĂ©cifiques

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    Les fourmis sont des organismes cibles appropriĂ©s pour les Ă©tudes environnementales. Au cours de notre Ă©tude, nous nous sommes focalisĂ©s sur les fourmis de la litiĂšre via l'application de deux mĂ©thodes de rĂ©colte complĂ©mentaires selon le protocole all (ants of leaf litter). Dans les forĂȘts naturelles de Guyane française, l'hĂ©tĂ©rogĂ©nĂ©itĂ© environnementale et les perturbations structurent les communautĂ©s de fourmis de la litiĂšre en influençant la richesse, la diversitĂ©, l'abondance et la densitĂ© en espĂšces ainsi que les compositions taxonomique et fonctionnelle. Chaque type de formation vĂ©gĂ©tale possĂšde une communautĂ© spĂ©cifique. La fragmentation et la conversion des forĂȘts en plantations ont entrainĂ© une altĂ©ration plus ou moins profonde des communautĂ©s; cette variabilitĂ© est fonction du type d agriculture et des espĂšces d'essences cultivĂ©es. Bien que l'altĂ©ration des communautĂ©s se soit rĂ©vĂ©lĂ©e maximale dans la plupart des monocultures, les plantations de cacaoyers ont un potentiel de conservation rĂ©el. Enfin, dans un contexte ou il est urgent de simplifier l'intĂ©gration des arthropodes dans les Ă©tudes de conservation, de contrĂŽle et de suivi de la santĂ© des Ă©cosystĂšmes terrestres, la mĂ©thode des rĂ©seaux de neurones est apparue comme un outil puissant pour mettre en Ă©vidence et analyser les patrons des communautĂ©s de fourmis.Ants are reliable and relevant target organisms for environmental surveys. In our study, we focused on litter-dwelling ants through the use of two complementary sampling methods that were implemented according to the ants of leaf litter (all) protocol. In pristine forests of french guiana, leaf-litter ant communities are structured by environmental heterogeneity and natural perturbations - which influence species richness, diversity, abundance and density, as well as taxonomic and functional composition. This results in habitat-specific communities for each vegetal formation. Forest fragmentation and conversion into monocultures have led to a more or less deep alteration of the ant communities; this variability depends on the type of agricultural system and cultivated tree species. Although the intensity of community alteration peaked in tree monocultures, cocoa plantation exhibited a real potential for native species conservation. Finally, in the current context where simplifying the integration of arthropods into conservation programs as well as into surveys designed to monitor and manage the environment is critical, the use of neural networks appears to be a powerful tool for reliably highlighting and analyzing ant communities patterns.CAYENNE-BU (973022101) / SudocSudocFranceF

    A type of unicoloniality within the native range of the fire ant Solenopsis saevissima

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    International audienceThe maintenance in the long run of a positive carbon balance under very low irradiance is a prerequisite for survival of tree seedlings below the canopy or in small gaps in a tropical rainforest. To provide a quantitative basis for this assumption, experiments were carried out to determine whether construction cost (CC) and payback time for leaves and support structures, as well as leaf life span (i) differ among species and (ii) display an irradiance-elicited plasticity. Experiments were also conducted to determine whether leaf life span correlates to CC and payback time and is close to the optimal longevity derived from an optimization model. Saplings from 13 tropical tree species were grown under three levels of irradiance. Specific-CC was computed, as well as CC scaled to leaf area at the metamer level. Photosynthesis was recorded over the leaf life span. Payback time was derived from CC and a simple photosynthesis model. Specific-CC displayed only little interspecific variability and irradiance-elicited plasticity, in contrast to CC scaled to leaf area. Leaf life span ranged from 4 months to >26 months among species, and was longest in seedlings grown under lowest irradiance. It was always much longer than payback time, even under the lowest irradiance. Leaves were shed when their photosynthesis had reached very low values, in contrast to what was predicted by an optimality model. The species ranking for the different traits was stable across irradiance treatments. The two pioneer species always displayed the smallest CC, leaf life span, and payback time. All species displayed a similar large irradiance-elicited plasticity

    Tatuidris kapasi sp. nov.: A New Armadillo Ant from French Guiana (Formicidae: Agroecomyrmecinae)

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    Tatuidris kapasisp. nov. (Formicidae: Agroecomyrmecinae), the second known species of “armadillo ant”, is described after a remarkable specimen collected in French Guiana. This species can be easily distinguished from Tatuidris tatusia by characters related to the shape of the mesosoma and petiole as well as to the pilosity, the sculpture, and the color

    The ecology and feeding habits of the arboreal trap-jawed ant Daceton armigerum.

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    Here we show that Daceton armigerum, an arboreal myrmicine ant whose workers are equipped with hypertrophied trap-jaw mandibles, is characterized by a set of unexpected biological traits including colony size, aggressiveness, trophobiosis and hunting behavior. The size of one colony has been evaluated at ca. 952,000 individuals. Intra- and interspecific aggressiveness were tested and an equiprobable null model used to show how D. armigerum colonies react vis-Ă -vis other arboreal ant species with large colonies; it happens that D. armigerum can share trees with certain of these species. As they hunt by sight, workers occupy their hunting areas only during the daytime, but stay on chemical trails between nests at night so that the center of their home range is occupied 24 hours a day. Workers tend different Hemiptera taxa (i.e., Coccidae, Pseudococcidae, Membracidae and Aethalionidae). Through group-hunting, short-range recruitment and spread-eagling prey, workers can capture a wide range of prey (up to 94.12 times the mean weight of foraging workers)
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