No description available.

Contexte: L’importance écologique des fourmis dans les écosystèmes terrestres justifie qu’elles soient considérées comme groupe cible pour des actions de conservation. De plus, de par leur abondance, leur facilité de récolte et leur réponse à des perturbations, elles présentent un potentiel intéressant comme groupe indicateur précoce de l’état de santé des écosystèmes. Par contre, pour le choix d’aires à protéger, leur utilité comme intégrateur des conditions de milieu par rapport à des indicateurs classiques tels que les assemblages de plantes n’est pas clairement établie. En d’autres termes, répondent-elles plus finement que les plantes à différentes conditions de milieu et dans ce cas doit-on s’attendre à trouver au sein de formations végétales comparables plusieurs types d’assemblages de foumis? Si tel est le cas, la méthode utilisant les assemblages de végétaux pour sélectionner les sites à protéger peut ne pas permettre une conservation efficace de la diversité des fourmis. Ce type de problématique s’aborde bien le long de gradients environnementaux. Pour faciliter l’interprétation des résultats en terme de réponse aux facteurs abiotiques il est préférable de limiter le nombre de facteurs qui varient en même temps. Dans ce sens, le Chaco sec paraguayen représente un système très favorable: faible déclivité, faibles variations de températures moyennes mais gamme très étendue de conditions de pluviométrie (350mm à 1000mm de précipitations moyennes annuelles) et des sols variables (texture limoneuse à sableuse). L’aridité est l’un des principaux facteurs pouvant limiter la diversité des fourmis soit directement en exerçant un stress physiologique sur les espèces, soit indirectement en limitant la productivité primaire de l’habitat. Les conditions édaphiques peuvent également avoir une influence en affectant par exemple la survie des colonies qui nidifient dans le sol. Objectifs: Les principaux buts de la thèse sont (1) de déterminer l’influence de l’aridité et des conditions édaphiques sur la distribution et la structure des assemblages de fourmis terricoles du sol en forêts tropicales sèches, (2) mettre en évidence les mécanismes qui facilitent la coexistence des espèces de fourmis à l’échelle locale, (3) déterminer si à l’échelle régionale les fourmis et les plantes répondent de façon similaire aux conditions du milieu. Méthode: Onze localités ont été échantillonnées le long d’un transect régional long de 400km. Au niveau de chaque localité, trois transects élémentaires longs de 200m et séparés les uns des autres par 200m ont été effectués. La myrmécofaune a été échantillonnée à l’aide de 20 pièges à fosse et de 20 Winkler par transect élémentaire. La végétation de chaque site a été caractérisée sur base de l’abondance de 45 espèces d’arbres ou d’arbustes caractéristiques de la flore chaquéenne. Les propriétés physico-chimiques du sol ont également été mesurées. A fine échelle, l’organisation spatio-temporelle d’un assemblage a été étudié dans une localité de référence. Résultats: Au total, plus de 50.000 spécimens correspondant à 206 espèces de fourmis ont été collectés avec en moyenne (± SD) 62 ± 10 espèces par localité. Pour un même effort d’échantillonnage, le nombre d’espèces de fourmis récoltées à l’aide des pièges à fosse augmente avec l’aridité et une tendance inverse est observée pour les Winkler. Puisque les Winkler peuvent entraîner une sévère sous-estimation de la diversité des fourmis d’un habitat, seules les données des pièges à fosse sont utilisées pour la suite des analyses. La diversité locale  des assemblages de fourmis n’apparaît corrélée ni à l’aridité, ni aux conditions édaphiques. En revanche, ces facteurs, et spécialement la texture du sol, influencent la composition des assemblages. Trois complexes myrmécofauniques sont mis en évidence: le premier dans la localité la plus sèche (350mm) et la plus sableuse (>90% de sable dans la fraction minérale du sol), le second dans la localité la plus humide (1000mm, sol argilo-limoneux) et le dernier dans des localités présentant de larges conditions de pluviométrie (350-850mm) et de sol (limoneux à sablo-limoneux). Les plantes répondent encore plus finement à ces facteurs abiotiques. A l’échelle locale, l’établissement d’une ségrégation spatio-temporelle fine des espèces de fourmis lors de l’exploitation des ressources alimentaires facilite la coexistence interspécifique. Cette ségrégation est engendrée par l’existence de deux compromis: l’un entre les capacités des espèces à dominer et à découvrir les ressources et l’autre entre la capacité de dominance et la tolérance aux températures élevées. Conclusions: Nos résultats contredisent l’hypothèse selon laquelle les fourmis répondent plus finement que les plantes aux conditions du milieu. A l’échelle du gradient étudié, une augmentation de l’aridité n’affecte pas la diversité des fourmis. La productivité de l’habitat ne semble pas déterminer la richesse des assemblages et la tolérance à l’aridité semble répandue au sein des Formicidae. La texture du sol apparaît être le facteur le plus déterminant des distributions spatiales observées. Dans le Chaco sec paraguayen, une sélection des sites à protéger sur base des assemblages végétaux est susceptible de maximiser la conservation de la diversité biologique des fourmis. Notre étude de la distribution de la myrmécofaune, basée sur la plus large gamme de pluviométrie envisagée à ce jour, pourra constituer le point de départ d'un suivi des assemblages de fourmis dominantes du Chaco sec paraguayen dans le but d'investiguer l'impact des changements climatiques globaux sur ces organismes.

Nesta tese, dados gravimétricos terrestres e de satélite foram combinados revelando que as bordas oeste e sul da Bacia do Paraná são caracterizadas por um forte gradiente que se estende por 2000 km, desde o cráton Rio Apa até a margem continental Atlântica na latitude do Sinclinal de Torres. Enquanto a Bacia do Paraná é caracterizada por anomalias Bouguer negativas (~-80 mGal), os crátons Rio de la Plata, Rio Tebicuary e Rio Apa e a Bacia do Chaco-Paraná são marcados por anomalias Bouguer positivas (~10 mGal). Dados sismológicos e de compensação isostática permitiram correlacionar a variação regional da amplitude das anomalias Bouguer à espessura crustal, de ~40 km na Bacia do Paraná para 30-35 km nos crátons. Essas observações geofísicas e a ocorrência de granitos cálcio-alcalinos de idade Neoproterozoica-Cambriana ao longo do gradiente gravimétrico indicam um ambiente tectônico de colisão e zona de subducção. A essa descontinuidade de escala litosférica denominamos Zona de Sutura do Oeste do Paraná (WPS Western Paraná Suture shear/zone). Dois perfis magnetotelúricos (MT) foram coletados para estudar a natureza e a estrutura elétrica da crosta e do manto litosférico através da WPS. O primeiro perfil se estende por 830 km desde o cráton Rio de la Plata, no Uruguai, até a parte sul da Bacia do Paraná. Modelagem inversa 2-D desses dados mostra que o manto superior no cráton Rio de la Plata é bastante resistivo (~2000 m) até 250 km de profundidade, enquanto o manto superior na Bacia do Paraná é geralmente mais condutivo e heterogêneo. Com base numa descontinuidade lateral de escala litosférica bem definida no modelo de resistividade, o limite nordeste do cráton Rio de la Plata é redefinido no norte do bloco Valentines. O segundo perfil se estende por 450 km na Argentina, entre o cráton Rio Tebicuary e a Bacia do Paraná. No modelo MT o cráton Rio Tebicuary é caracterizado por um manto superior resistivo (2000 m) até 150 km de profundidade. A litosfera na Bacia do Paraná é menos resistiva (~500 m) e provavelmente menos espessa (~80 km). Um perfil MT entre o cráton Rio Apa e a Bacia do Paraná mostra estrutura geoelétrica similar. As estruturas elétricas observadas, juntamente com dados geocronológicos, geoquímicos, sismológicos e densidade, sugerem processos de refertilização na litosfera da Bacia do Paraná. Sucessões de anomalias condutivas em antigas zonas de sutura e resistivas em blocos e terrenos juvenis nos modelos geoelétricos, integradas a dados geológicos, indicam um processo de acresção horizontal e uma progressão de subducções de placas litosféricas oceânicas, sendo a mais jovem sob a litosfera continental da Bacia do Paraná. Os resultados obtidos mostram que a WPS é uma descontinuidade litosférica de primeira ordem que marca o fechamento de um oceano durante os estágios finais da formação do Gondwana Sul-Ocidental no Neoproterozoico-Cambriano. / In this thesis, terrestrial and satellite gravity data were integrated revealing a steep gravity gradient at the western and southern borders of the Paraná Basin. This gradient extends for 2,000 km from the Rio Apa craton to the Brazilian Atlantic margin at Torres Syncline latitude. Negative Bouguer anomalies (~-80 mGal) occur over the Paraná Basin, whereas positive anomalies are observed at Rio de la Plata, Rio Tebicuary and Rio Apa cratons, as well as Chaco-Paraná Basin. Seismological data and isostasy correlate the gravity gradient with crustal thickness variation, being thicker in the Paraná Basin (~40 km) and shallower in the cratons (~35 km). These geophysical observations and the presence of Neoproterozoic calc-alkaline granites along the gravity gradient suggest a collisional and subduction tectonic setting. This lithospheric discontinuity is hereafter referred to as Western Paraná Suture/shear zone (WPS). Two magnetotelluric (MT) profiles perpendicular to WPS were set up to study the electrical structure and nature of the crust and lithospheric mantle across the suture zone. The first profile, 830 km long, extends northward from Rio de la Plata craton, in Uruguay, to Paraná Basin southern border. 2-D inversion of this MT profile shows that the Rio de la Plata craton upper mantle is highly resistive (~2000 m) down to 250 km depth, whereas the Paraná Basin lithosphere is conductive and heterogeneous. Based on a lithospheric-scale lateral discontinuity in the resistivity model, the Rio de la Plata craton northern limit is redefined to the Valentines block northern limit. The second profile is 450 km long and extends from Rio Tebicuary craton to the Paraná Basin, and all stations are in Argentina. The MT model shows that Rio Tebicuary craton is characterized by a resistive lithosphere (2000 m) down to 150 km depth. The Paraná Basin lithosphere is less resistive (~500 m) and probably thinner (~80 km). Previous MT study between the Rio Apa craton and the Paraná basin, to the north, shows a similar electrical structure. These electrical characteristics, integrated with geochronological, geochemical, seismological and density data, suggest that Paraná Basin lithosphere underwent refertilization episodes. In the geoelectrical models, a series of resistive blocks and juvenile terrains and conductive anomalies in suture zone relics, integrated with geological data, suggest a horizontal accretionary process by means of progressive oceanic lithospheres subductions, the youngest one occurring below the Paraná Basin continental lithosphere. Altogether, these results show that the WPS is a first order lithosphere discontinuity, a site of an ocean closure during the South-Western Gondwana late stages of amalgamation in Neoproterozoic/Cambrian times.

Nesta tese, dados gravimétricos terrestres e de satélite foram combinados revelando que as bordas oeste e sul da Bacia do Paraná são caracterizadas por um forte gradiente que se estende por 2000 km, desde o cráton Rio Apa até a margem continental Atlântica na latitude do Sinclinal de Torres. Enquanto a Bacia do Paraná é caracterizada por anomalias Bouguer negativas (~-80 mGal), os crátons Rio de la Plata, Rio Tebicuary e Rio Apa e a Bacia do Chaco-Paraná são marcados por anomalias Bouguer positivas (~10 mGal). Dados sismológicos e de compensação isostática permitiram correlacionar a variação regional da amplitude das anomalias Bouguer à espessura crustal, de ~40 km na Bacia do Paraná para 30-35 km nos crátons. Essas observações geofísicas e a ocorrência de granitos cálcio-alcalinos de idade Neoproterozoica-Cambriana ao longo do gradiente gravimétrico indicam um ambiente tectônico de colisão e zona de subducção. A essa descontinuidade de escala litosférica denominamos Zona de Sutura do Oeste do Paraná (WPS Western Paraná Suture shear/zone). Dois perfis magnetotelúricos (MT) foram coletados para estudar a natureza e a estrutura elétrica da crosta e do manto litosférico através da WPS. O primeiro perfil se estende por 830 km desde o cráton Rio de la Plata, no Uruguai, até a parte sul da Bacia do Paraná. Modelagem inversa 2-D desses dados mostra que o manto superior no cráton Rio de la Plata é bastante resistivo (~2000 m) até 250 km de profundidade, enquanto o manto superior na Bacia do Paraná é geralmente mais condutivo e heterogêneo. Com base numa descontinuidade lateral de escala litosférica bem definida no modelo de resistividade, o limite nordeste do cráton Rio de la Plata é redefinido no norte do bloco Valentines. O segundo perfil se estende por 450 km na Argentina, entre o cráton Rio Tebicuary e a Bacia do Paraná. No modelo MT o cráton Rio Tebicuary é caracterizado por um manto superior resistivo (2000 m) até 150 km de profundidade. A litosfera na Bacia do Paraná é menos resistiva (~500 m) e provavelmente menos espessa (~80 km). Um perfil MT entre o cráton Rio Apa e a Bacia do Paraná mostra estrutura geoelétrica similar. As estruturas elétricas observadas, juntamente com dados geocronológicos, geoquímicos, sismológicos e densidade, sugerem processos de refertilização na litosfera da Bacia do Paraná. Sucessões de anomalias condutivas em antigas zonas de sutura e resistivas em blocos e terrenos juvenis nos modelos geoelétricos, integradas a dados geológicos, indicam um processo de acresção horizontal e uma progressão de subducções de placas litosféricas oceânicas, sendo a mais jovem sob a litosfera continental da Bacia do Paraná. Os resultados obtidos mostram que a WPS é uma descontinuidade litosférica de primeira ordem que marca o fechamento de um oceano durante os estágios finais da formação do Gondwana Sul-Ocidental no Neoproterozoico-Cambriano. / In this thesis, terrestrial and satellite gravity data were integrated revealing a steep gravity gradient at the western and southern borders of the Paraná Basin. This gradient extends for 2,000 km from the Rio Apa craton to the Brazilian Atlantic margin at Torres Syncline latitude. Negative Bouguer anomalies (~-80 mGal) occur over the Paraná Basin, whereas positive anomalies are observed at Rio de la Plata, Rio Tebicuary and Rio Apa cratons, as well as Chaco-Paraná Basin. Seismological data and isostasy correlate the gravity gradient with crustal thickness variation, being thicker in the Paraná Basin (~40 km) and shallower in the cratons (~35 km). These geophysical observations and the presence of Neoproterozoic calc-alkaline granites along the gravity gradient suggest a collisional and subduction tectonic setting. This lithospheric discontinuity is hereafter referred to as Western Paraná Suture/shear zone (WPS). Two magnetotelluric (MT) profiles perpendicular to WPS were set up to study the electrical structure and nature of the crust and lithospheric mantle across the suture zone. The first profile, 830 km long, extends northward from Rio de la Plata craton, in Uruguay, to Paraná Basin southern border. 2-D inversion of this MT profile shows that the Rio de la Plata craton upper mantle is highly resistive (~2000 m) down to 250 km depth, whereas the Paraná Basin lithosphere is conductive and heterogeneous. Based on a lithospheric-scale lateral discontinuity in the resistivity model, the Rio de la Plata craton northern limit is redefined to the Valentines block northern limit. The second profile is 450 km long and extends from Rio Tebicuary craton to the Paraná Basin, and all stations are in Argentina. The MT model shows that Rio Tebicuary craton is characterized by a resistive lithosphere (2000 m) down to 150 km depth. The Paraná Basin lithosphere is less resistive (~500 m) and probably thinner (~80 km). Previous MT study between the Rio Apa craton and the Paraná basin, to the north, shows a similar electrical structure. These electrical characteristics, integrated with geochronological, geochemical, seismological and density data, suggest that Paraná Basin lithosphere underwent refertilization episodes. In the geoelectrical models, a series of resistive blocks and juvenile terrains and conductive anomalies in suture zone relics, integrated with geological data, suggest a horizontal accretionary process by means of progressive oceanic lithospheres subductions, the youngest one occurring below the Paraná Basin continental lithosphere. Altogether, these results show that the WPS is a first order lithosphere discontinuity, a site of an ocean closure during the South-Western Gondwana late stages of amalgamation in Neoproterozoic/Cambrian times.

Orientadores: Anete Pereira de Souza, Ângela Lúcia Bagnatori Sartori / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-26T12:24:27Z (GMT). No. of bitstreams: 1 Alves_FabiodeMatos_D.pdf: 1133051 bytes, checksum: 2103a58113fa28c260e7ecbccd72f761 (MD5) Previous issue date: 2014 / Resumo: As áreas de Chaco em território sulamericano, representam a maior área de floresta seca contínua do continente. No Brasil, estas áreas são encontradas principalmente na porção sudeste do domínio, no estado de Mato Grosso do Sul, região sul-pantaneira. Talvez por serem áreas de pouca cobertura, o seu conhecimento ainda é incipiente. Embora novos projetos tenham sido realizados nestas áreas nos últimos anos, a sua crescente supressão pelas atividades de pecuária extensiva tem sido preocupante. Não há na região qualquer tipo de Unidade de Conservação a fim de preservar o patrimônio genético das espécies que lá ocorrem, muitas das quais têm sua distribuição limitada a esta fitofisionomia. Desta forma, estudos que visem o conhecimento da variabilidade genética ainda existente, principalmente em áreas em processo de degradação são fundamentais para o conhecimento da atual situação das populações existentes, para indicar métodos de conservação, bem como a propor políticas públicas visando a manutenção e conservação do Chaco brasileiro. A fim de efetuar estimativas da diversidade genética, o uso de marcadores moleculares tem sido empregado em diversos estudos de populações nas diversas formações vegetacionais, principalmente no Brasil. Os microssatélites (SSRs), tem se mostrado uma ferramenta versátil e confiável. O presente estudo teve por objetivo efetuar um estudo genético populacional de Prosopis rubriflora e P. ruscifolia em áreas de Chaco brasileiro, com distintos níveis de perturbação antrópica e ainda, avaliar o sistema de reprodução, pelo uso de progênies, em P. rubriflora, com o emprego de microssatélites. Inicialmente foi construída uma biblioteca enriquecida em microssatélites para P. rubriflora e P. ruscifolia, empregando-se DNA genômico extraído de material foliar. Foram obtidos 21 marcadores microssatélites polimórficos, sendo nove deles para P. rubriflora e 12 para P. ruscifolia. Posteriormente, foram amostrados indivíduos de ambas as espécies em 19 áreas remanescentes de Chaco em Mato Grosso do Sul, com diferentes níveis de perturbação. Uma área aparentemente conservada na região foi selecionada para a amostragem das progênies de P. rubriflora em dois anos consecutivos de amostragem. A genotipagem foi efetuada por meio de sequenciador automático ABI 3500 Genetic Analyzers. Os resultados da genotipagem foram utilizados para estimar os parâmetros de diversidade genética, tendo eles sido similares em ambos os táxons, como o He = 0,59 em P. rubriflora e He = 0,60 em P. ruscifolia. Foi detectado efeito de gargalo populacional em todos os remanescentes de P. rubriflora e na maioria de P. ruscifolia. Constatou-se ausência de estruturação genética intrapopulacional em P. rubriflora (FIS = 0,042), bem como estruturação genética interpopulações moderada (FST = 0,057) resultante da nítida separação dos remanescentes de Nioaque e Porto Murtinho. Em P. ruscifolia foi encontrado, indícios de estruturação ao nível intrapopulacional, e baixa estruturação interpopulacional (FIS = 0,138 e FST = 0,042). Identificou-se que P. rubriflora apresenta um sistema de reprodução preferencialmente alógamo e deve apresentar mecanismos bastante efetivos para evitar a endogamia, principalmente, devido a maioria dos polinizadores apresentarem baixa dispersão entre as plantas. As duas espécies deste estudo apresentam respostas relativamente distintas às perturbações ambientais nas áreas chaquenhas, sendo que P. ruscifolia parece ser mais vulnerável às degradações em comparação a P. rubriflora. Assim, espera-se que estes dados sirvam de apoio para medidas conservacionistas para as áreas chaquenhas, que são extremamente diminutas em território brasileiro / Abstract: Chaquenian areas in Brazil have a short range distribution and are found mainly in Mato Grosso do Sul county, South Pantanal region, and it comprehends a narrow coverage, is possibly the main reason for the poor knowledge of these areas. While new projects were conducted in these areas in recent years, the suppression of the remnant areas due to cattle breeding activities has been a source of concern, because there is no conservation units to protect the genetic heritage of the native species those counties, where the Chaco¿s remnants occur. In this scenario, studies aiming to increase the knowledge of the current genetic diversity, specially where environmental disturbing processes take place, provides important data to understand the current situation of the remaining populations. Moreover, with this study it is possible to indicate conservation measures and public politics aiming at the maintenance and conservation Brazilian chaquenian areas. In order to estimate the genetic diversity, molecular markers have been used in several population studies from different vegetation formations, mainly in Brazil. Microsatellites (SSRs) is one of the most popular molecular markers, considerated a versatile and reliable tool. This study aimed a population genetics study with Prosopis rubriflora and P. ruscifolia in Brazilian chaquenian areas with distinct disturbing levels and conducts a mating system study with P. rubriflora. Initially, we built an enriched library of microsatellites from P. rubriflora and P. ruscifolia using leaf tissue to extract genomic material, which allowed to obtain 21 polymorphic markers, where, nine markers were developed for P. rubriflora and 12 for P. ruscifolia. Then, we sampled individuals of both species in 19 remnant areas of Chaco in Mato Grosso do Sul¿s county, with different disturbance levels. We selected one apparently conserved remnant for sampling progenies of P. rubriflora, with two consecutive years of sampling. The genotyping procedure was performed using an automatic sequencer ABI 3500 Genetic Analyzers. Through the genotyped data, we estimated genetic diversity parameters and observed results He = 0.59 for P. rubriflora and He = 0.60 for P. ruscifolia. We were able to detect a bottleneck effect in all remnants of P. rubriflora and also, in most of P. ruscifolia remnant areas. We reported a not significant intrapopulation genetic structure in P. rubriflora (FIS = 0.042) although with moderated structure between-populations (FST= 0.057) was observed, with the separation of two distinct populations for the studied remnants. A low, but significant genetic structure within and a low genetic structure between populations (FIS = 0.138 and FST = 0.042), is reported for P. ruscifolia in this study. The analysis showed an outcrossing mating system for P. rubriflora suggesting a very effective mechanism to prevent inbreeding, even with the pollinators of predominently low dispersion. The species in this study presents a relatively distinct response to environmental disturbance caused by anthropic factors in chaquenhas areas, P. ruscifolia seems to be more vulnerable to degradations as compared to P. rubriflora. Despite this scenario, we hope that these available data will aid into conservation measures for chaquenhas areas, which is distributed in a narrow range in Brazilian¿s territory / Doutorado / Biologia Vegetal / Doutor em Biologia Vegetal

Beginning in the tenth century, Chaco Canyon emerged as an important center whose influence shaped subsequent cultural developments throughout the Four Corners area of the American Southwest. Archaeologists investigating the prehistory of Chaco Canyon have long been impressed by its massive architecture, evidence of widespread trading activities, and ancient roadways that extended across the region. Research on Chaco Canyon today is focused on what the remains indicate about the social, political, and ideological organization of the Chacoan people. Communities with great houses located some distance away are of particular interest, because determining how and why peripheral areas became associated with the central canyon provides insight into the evolution of the Chacoan tradition. This volume brings together twelve chapters by archaeologists who suggest that the relationship between Chaco Canyon and outlying communities was not only complex but highly variable. Their new research reveals that the most distant groups may have simply appropriated Chacoan symbolism for influencing local social and political relationships, whereas many of the nearest communities appear to have interacted closely with the central canyon--perhaps even living there on a seasonal basis. The multifaceted approach taken by these authors provides different and refreshing perspectives on Chaco. Their contributions offer new insight into what a Chacoan community is and shed light on the nature of interactions among prehistoric communities. "The multifaceted approach . . . provides different and sometimes refreshing perspectives on Chaco. Their contributions offer new insight into what a Chacoan community is, and they shed new light on the nature of interactions among prehistoric communities." —Traditional Dwellings & Settlements Review

Les espaces ruraux argentins connaissent des transformations profondes liées à la consolidation d'un modèle d'agriculture entrepreneuriale et exportatrice. Dans les régions extra-pampéennes, les conséquences de ce modèle sont sujettes à controverses et sont décrites en termes de déterritorialisation et de fragmentation. Dans ce contexte, nous interrogeons les nouveaux principes d'action publique de développement rural qui conduisent à la « territorialisation » de l'action publique et au « renforcement institutionnel », visant à consolider les capacités d'action et de participation des acteurs locaux. A partir d'expériences observées dans le Chaco argentin, la thèse se centre sur la configuration du champ du développement rural et sur l'articulation de l'action publique et de l'action collective autour d'innovations territoriales et institutionnelles. Celles-ci sont interprétées comme des traductions locales des principes d'action publique internationalisés auxquelles participent de nouveaux acteurs : techniciens et organisations de petits producteurs. La territorialisation de l'action publique permet de questionner l'émergence d'un nouveau pacte territorial, compris comme une relation Etat-territoire. La thèse démontre que ce pacte intègre les contradictions socio-spatiales entre différentes formes de territorialisation de l'activité agricole et conduit à la fragmentation du secteur agricole en deux référentiels : un référentiel de développement rural, au centre duquel se trouve l'agriculture familiale, et un référentiel productiviste au centre duquel se trouve l'agriculture entrepreneuriale.

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The thesis examines Bolivian fiction written about the war with Paraguay (1932-35), known as the Chaco War. The study takes two different perspectives: the first considers the fiction as works of literature, and studies three major aspects of fictional writing: narrative organization, characterization arid figurative language, in order to investigate the constraints imposed upon writers who produce fiction about an historical event, (in this instance a military conflict). The second perspective views the works of fiction as historical documents and assesses their informative value by comparing factual information supplied in the novels with that provided in historiographical accounts and also by examining the kind of information which is the peculiar contribution of fiction to the understanding of an historical event. These two examinations are undertaken in Chapters V and VI respectively, and constitute the main body of the thesis. In order to place them in a wider context, the thesis considers previous critical studies of Chaco War fiction (in the Introduction). There follows a study of the relationship between the writing of contemporary history and documentary fiction (Chapter I), a brief summary of the Chaco War (Chapter II), an examination of some possible influences and precedents (Chapter III) and a survey of the writers and the works of Bolivian fiction of the Chaco War (Chapter IV). The conclusion suggests that the problems encountered by writers of documentary fiction are those faced by any naturalist writer, compounded here by the nature of the subject matter. If they cannot fully succeed on an artistic level, however, these works do provide a view of the historical facts of the war which is reasonably accurate. In addition they lead to a distinctive understanding of the war as an historical experience which no historiographical work can produce.

abstract: The health situation of indigenous peoples is comparable to that of the world's poorest populations, but with the additional burdens of social and cultural marginalization, geographic and cultural barriers to accessing health services, and, in some areas, appropriation of land and natural resources. Cultural transmission (the transfer of beliefs, ideas, and behaviors from one culture to another) from outsider health institutions should presumably aid in closing this health gap by transferring knowledge, practices, and infrastructure to prevent and treat disease. This study examines the biosocial construction of the disease ecology of tuberculosis (TB) in indigenous communities of the Paraguayan Chaco with varying degrees of cultural transmission from outside institutions (government, religious, and NGOs), to determine the influence of cultural transmission on local disease ecologies. Using a biocultural epidemiological framework for the analysis of human infectious disease ecology, this study employed an interdisciplinary, mixed methods approach to examine the interactions of host, pathogen, and the environment in the Paraguayan Chaco. Three case studies examining aspects of TB disease ecology in indigenous communities are presented: (1) The effective cultural transmission of biomedical knowledge to isolated communities, (2) Public health infrastructure, hygiene, and the prevalence of intestinal parasites: co-morbidities that promote the progression to active TB disease, and (3) Community-level risk factors for TB and indigenous TB burden. Findings from the case studies suggest that greater influence from outside institutions was not associated with greater adoption of biomedical knowledge of TB. The prevalence of helminthiasis was unexpectedly low, but infection with giardia was common, even in a community with cleaner water sources. Communities with a health post were more likely to report active adult TB, while communities with more education were less likely to report active pediatric TB, suggesting that healthcare access is the major determinant of TB detection. More research is needed on the role of non-indigenous community residents and other measures of acculturation or integration in TB outcomes, especially at the household level. Indigenous TB burden in the Chaco is disproportionately high, and better understanding of the mechanisms that produce higher incidence and prevalence of the disease is needed. / Dissertation/Thesis / Doctoral Dissertation Social Science and Health 2014