Dissertations / Theses: 'Ecologie parasite'

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Garnier, Romain. "Ecologie évolutive de la transmission maternelle d'anticorps." Thesis, Montpellier, SupAgro, 2011. http://www.theses.fr/2011NSAM0045/document.

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Chez les vertébrés, la réponse immunitaire acquise représente un mécanisme sophistiqué de réponse face aux parasites dont l‟une des particularités est la possibilité qu‟il offre aux mères de transférer certains de ses effecteurs à leurs nouveau-nés. Pourtant, malgré un intérêt croissant pour les effets maternels, les déterminants écologiques et évolutifs du transfert d‟anticorps maternels n‟ont pas encore été beaucoup étudiés. L‟analyse d‟un cadre théorique spécialement développé pour inclure le transfert transgénérationnel d‟immunité montre que l‟évolution de la capacité à transférer une immunité temporaire aux jeunes dépend des caractéristiques de l‟hôte et du parasite. En particulier, l‟augmentation de l‟espérance de vie de l‟hôte favorise l‟évolution de réponses immunitaires acquises, et la protection conférée par ces réponses est aussi supposée durer plus longtemps chez les hôtes longévifs. En accord avec cette prédiction, une étude de vaccination transgénérationnelle chez une espèce d‟oiseau de mer longévive a permis de mettre en évidence une demi-vie des anticorps maternels particulièrement longue. Les conditions sociales sont aussi un élément clé, et chez une espèce de mammifère, j‟ai pu montrer qu‟elles permettent un élargissement du répertoire d‟anticorps maternels. Le transfert d‟anticorps maternels est aussi à même de modifier les dynamiques épidémiologiques et pourrait présenter un atout non négligeable si la vaccination était utilisée en conservation. Enfin, ce mécanisme pourrait être mis à profit pour estimer l‟exposition des mères, et ainsi inférer la dispersion entre différentes zones d‟habitat
In vertebrate species, acquired immune response represents a sophisticated protection mechanism against parasites that has the particularity of enabling mothers to transmit part of its effectors to their newborns. Yet, despite an increasing interest in maternal effects, ecological and evolutionary determinants of the transfer of maternal antibodies remain poorly studied. The analysis of a theoretical framework specially developed to include a transgenerational transfer of immunity show that the evolution of an ability to temporarily protect offspring depends on the characteristics of both the host and the parasite. In particular, increasing the life span of the host favors the evolution of acquired immune responses and increases the duration of the protection offered by these mechanisms. Accordingly, a transgenerational vaccination study in a long-lived seabird revealed a particularly long half-life of maternal antibodies. Social conditions also proved important in a mammal species as they can allow for the broadening of the repertoire covered by maternal antibodies. The transfer of maternal antibodies could also modify epidemiological dynamics and could bbe an interesting asset if vaccination was used as a conservation tool. Finally, this mechanism could be used to estimate the exposure of mother and thus infer the dispersal rate between different habitat patches

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Fedna, Jimmy. "Prévalence du parasite Angiostrongylus cantonensis en Haïti chez les rats et gastéropodes." Electronic Thesis or Diss., Bourgogne Franche-Comté, 2024. http://www.theses.fr/2024UBFCD017.

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Ma recherche examine la prévalence et la répartition du parasite Angiostrongylus cantonensis en Haïti, également connu sous le nom de ver pulmonaire du rat, et qui est la première cause de méningite à éosinophiles chez l’homme dans le monde. Ce parasite a un cycle de vie complexe impliquant à la fois des hôtes définitifs (rats) et des hôtes intermédiaires (escargots et les limaces). J’ai documenté l'écologie du parasite et sa persistance deux décennies après sa découverte initiale dans le pays. Trois objectifs ont été fixés : synthétiser les connaissances sur les dimensions spatiales et écologiques d’A. cantonensis, déterminer sa présence et sa répartition en Haïti parmi les populations de rats et de gastéropodes à l'aide d'analyses moléculaires et morphologiques, et identifier les similitudes génétiques entre les souches haïtiennes et celles provenant d’autres régions du monde. Nous avons ciblé deux contextes écologiques contrastés : la vallée de l'Artibonite (milieu rural) et la zone urbaine de Port-au-Prince. L'échantillonnage a eu lieu pendant la saison des pluies et à la fin de la saison des pluies en raison de l'influence potentielle de la saisonnalité hydrologique sur la prévalence du parasite.Une revue systématique utilisant la méthode PRISMA a synthétisé les connaissances existantes sur la niche écologique du parasite, en mettant l'accent sur les facteurs abiotiques et biotiques affectant sa dynamique. Soixante-dix rats ont été capturés :23 Rattus norvegicus et 47 Rattus rattus. Sous la loupe binoculaire, nous avons récupéré des vers adultes chez seulement cinq rats (7%, 5/70) mais la détection moléculaire a révélé une prévalence d'A. cantonensis dans les poumons de rat de 31,4 %, (22/70), le parasite étant détecté dans quatre des huit sites, dont Port-au-Prince. La prévalence du parasite n’était pas reliée de manière significative aux variables prédictives telles que l'âge, la saison, le sexe et l'espèce de rat. Un seul haplotype COX1, le génotype II-G, a été identifié en Haïti, ce qui suggère une large répartition similaire à celle d'autres régions. La technique qPCR AcanR3990 a permis d'identifier deux échantillons positifs d'espèces de gastéropodes : Subulina octona à Port-au-Prince et une limace de la famille des Veronicellidae dans l’Artibonite, concordant avec la présence du parasite retrouvé chez les rats à ces endroits.C'est la première étude sur A. cantonensis en Haïti portant à la fois sur les hôtes définitifs et intermédiaires. Les diagnostics moléculaires par PCR révèlent une prévalence plus élevée que l'identification morphologique, ce qui est prometteur pour l'étude systématique de la contamination potentielle des espèces hôtes. Les résultats indiquent une endémicité du parasite potentiellement principalement liée à deux espèces de gastéropodes : l'escargot terrestre S. octona et les limaces Veronicellidae, ainsi que les rats R. rattus et R. norvegicus, soulignant les risques importants pour la santé des populations locales
My research examines the prevalence and distribution of the parasite Angiostrongylus cantonensis, also known as the rat lungworm, in Haiti. It is the leading cause of eosinophilic meningitis in humans worldwide. This parasite has a complex life cycle involving definitive hosts (rats) and intermediate hosts (snails and slugs). I documented the parasite's ecology and persistence two decades after its initial discovery in the country. Three objectives were set: synthesizing knowledge on the spatial and ecological dimensions of A. cantonensis’ niche, determining its presence and distribution in Haiti among rat and gastropod populations using molecular and morphological analyses, and identifying genetic similarities between Haitian strains and those from other regions of the world. We targeted two contrasting ecological contexts: the Artibonite Valley (rural environment) and the urban area of Port-au-Prince. Sampling occurred during and at the end of the rainy season due to the potential influence of hydrological seasonality on parasite prevalence. A systematic review using the PRISMA method synthesized existing knowledge on the parasite's ecological niche, focusing on abiotic and biotic factors affecting its dynamics. Seventy rats were captured:23 Rattus norvegicus and 47 Rattus rattus. Under a binocular loupe, we recovered adult worms from only five rats (7%, 5/70), but molecular detection revealed a prevalence of A. cantonensis in rat lungs of 31.4% (22/70), with the parasite detected in four of the eight sites, including Port-au-Prince. Parasite prevalence was not significantly related to predictive variables such as age, season, sex, and rat species. Only one COX1 haplotype, genotype II-G, was identified in Haiti, suggesting a widespread distribution similar to other regions. The qPCR technique AcanR3990 identified two positive samples of gastropod species: Subulina octona in Port-au-Prince and a Veronicellidae slug in the Artibonite, indicating the presence of the parasite found in rats at these locations. This is the first study on A. cantonensis in Haiti addressing both definitive and intermediate hosts. Molecular diagnostics by PCR reveal a higher prevalence than morphological identification, promising for the systematic study of potential host species contamination. Results indicate that endemicity of the parasite may primarily be linked to two gastropod species: the land snail S. octona and Veronicellidae slugs, as well as R. rattus and R. norvegicus rats, highlighting significant health risks for local populations

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Jossart, Quentin. "Ecologie moléculaire d'une relation hôte-parasite en contexte insulaire marin: crabes parasites des oursins spatangues en Mer des Caraïbes." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209237.

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Comparer les structures génétiques des populations d’un couple hôte-parasite permet d’évaluer les facteurs qui façonnent la dispersion ainsi que la potentialité d’adaptation locale de ces espèces. Le modèle étudié est le crabe ectoparasite Dissodactylus primitivus et son oursin-hôte Meoma ventricosa, endémiques des Caraïbes et des côtes américaines voisines.

En étudiant des populations le long de l’arc antillais et de la côte panaméenne, ce travail a mis en évidence que la structure génétique des populations du parasite D. primitivus diffère fortement de celle de son hôte M. ventricosa (microsatellites et cytochrome oxydase I). En effet, alors que les populations du parasite présentent une différenciation au sein de cette région, celles de l’hôte sont génétiquement homogènes. Ce contraste peut être expliqué par des caractères biologiques et écologiques (fécondité, habilité à la nage, disponibilité de l’habitat) et suggère des potentialités d’adaptation locale distinctes. La distance géographique semble être importante dans la structuration des populations du crabe mais la courantologie ou encore des évènements passés (glaciations) jouent également un rôle. A l’échelle d’une même île, les crabes ne présentent pas de différenciation entre des sites distincts. En outre, nous avons pu montrer que des crabes issus d’hôtes d’espèces différentes ne sont pas différenciés génétiquement ce qui pourrait être liée à la mobilité des crabes adultes. Par des analyses de paternité, nous avons souligné cette mobilité, démontrant que le mode de reproduction du crabe est de la polygamie mais aussi que des accouplements pouvaient avoir lieu entre crabes d’espèces hôtes distinctes.

Doctorat en Sciences
info:eu-repo/semantics/nonPublished

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GIUDICI, CLAUDIO JUAN. "Correspondances entre les variabilites morphologique et ecologique chez le nematode haemonchus placei, parasite de bovins." Tours, 1999. http://www.theses.fr/1999TOUR4027.

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Les nematodes trichostrongylides ont un cycle en deux phase, l'un parasitaire chez les ruminants, l'autre libre sur le paturage. Ils sont tres repandus de part le monde chez les ruminants domestiques. Leur pathogenicite a amene de nombreuses etudes a etre realisees, le plus souvent sur des problemes tres appliques (impact sur la sante, moyens de lutte etc. ). Des etudes de systematique, de genetique et d'ecologie manquent pour ces nematodes aux capacites evolutives importantes. Le cas d'haemonchus placei est particulierement bien representatif : son statut taxinomique a ete bouleverse plusieurs fois, le polymorphisme morphologique des femelles a ete decrit avec de lourdes incertitudes, et les aptitudes ecologiques de l'espece et de ses morphes, ont ete a peine evoquees. En fait, ce nematode tres frequent n'a jamais ete completement decrit, et c'est donc a cette premiere entreprise que nous nous sommes attache. Au cours de cette description nous avons remarque que trois entites se degageaient nettement, l'une presente en australie, et les deux autres en amerique du nord et du sud et en afrique de l'ouest. L'importance de ces differences nous a conduit a definir trois sous-especes h. Placei placei (australie), et h. Placei argentinensis (ameriques) et h. Placei africanus (afrique). Contrairement a ce que nous supposions, par les quelques travaux realises anterieurement et en raison de la similarite avec haemonchus contortus, seulement deux morphes femelles (linguiforme et boutonnes) sont presents, le morphe lisse etant absent. Les deux morphes sont retrouves en proportions tres differentes d'un site a l'autre : le morphe linguiforme passe ainsi de 10% en mauritanie a 96% en cote d'ivoire (h. P. Africanus) et de 14% au mexique a 76% au bresil (h. P. Argentinensis). Ces proportions sont stables sur un site. Nous avons emis l'hypothese que ces morphes etait controles genetiquement et qu'ils etaient egalement indicateurs d'aptitudes ecologiques bien definies. Nous avons selectionne les deux morphes, en nous fondant sur l'aspect des femelles, les males correspondants n'etant pas differenciables. En 4 a 5 generations de selections menees chez des agneaux, nous obtenons des lignees linguiformes ou boutonnees qui comportent plus de 90% du morphe selectionne. Le mecanisme genetique retenu est celui d'un locus a deux alleles, le morphe linguiforme dominant le morphe boutonne. Nous avons d'ailleurs eu l'occasion de verifier que la fitness (ou succes reproductif) des linguiformes etait superieure dans nos conditions de selection (primo-infestations, hotes non electifs mais immuno-deprimes, et phase libre realisee, en conditions optimales). Dans les conditions naturelles, la fitness dependra vraisemblablement du type d'hote (electif : bovin, ou non : ovin ou caprin) et de l'environnement climatique. Il ressort que le morphe linguiforme a une capacite d'infestation superieure des hotes electifs bovins et que le morphe boutonne par contre s'etablit bien chez les hotes non electifs. Les capacites a se developper au cours de la phase libre sont superieures pour le morphe bouton dans les regions seches et le morphe linguiforme dans les regions humides, ce qui est corrobore par les etudes d'ecologie experimentale. Les assemblages de morphotypes correspondent donc a des adaptation regionales qui pourraient etre appelees ecotypes. H. Placei s'est revele un nematode polymorphe aux aptitudes diversifiees, bien que notre etude n'ait porte que sur des isolats africains et americains et un isolat australien. Il serait interessant de l'etudier a une plus large echelle (australasie comprise) pour definir l'ensemble des sous-especes, de tenter d'expliquer leur apparition par les migrations des bovins hotes a travers les continents. Il serait egalement interessant d'apprecier le polymorphisme et sa fonction adaptative au sein de chaque sous-espece.

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Beltran, S. "Monogamie et changements de partenaires chez un parasite monogame, Schistosoma mansoni." Phd thesis, Université de Perpignan, 2009. http://tel.archives-ouvertes.fr/tel-00939328.

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La monogamie est un système d'appariement qui lie une seule femelle à un seul mâle. Cette monogamie peut être définie comme sociale et génétique (au-delà de l'observation du couple, la descendance est seulement issue de ce couple, aucun changement de partenaire n'apparaît), ou comme sociale et non génétique (dans ce cas, des infidélités ou des divorces peuvent être observés). Ce système d'appariement est très rare dans le monde animal. Il concerne moins de 1% des animaux et la majeure partie des études sur le monogamie a été réalisée sur des vertébrés (notamment sur les oiseaux dont 90% des espèces présentent ce système monogame). Plus rares sont les études réalisées sur les invertébrés (quelques cas de monogamie étudiée chez des crustacés, des insectes ...). Pourtant l'étude de la monogamie à un niveau taxonomique inférieur permet de comprendre ses caractéristiques en éliminant la complexité sociale (apprentissage, imitation ...) présente chez les vertébrés. Schistosoma mansoni est un parasite (responsable de la bilharziose) qui présente plusieurs aspects intéressants du point de vue système d'appariement : (1) la femelle vit dans le canal gynéchophore de son mâle, nous observons bien un couple formé d'une seule femelle et d'un seul mâle, il s'agit donc d'une monogamie sociale ; (2) S. mansoni est l'espèce monogame de rang taxonomique le plus bas à notre connaissance, ce qui permet d'éliminer au maximum les biais de complexité sociale cités précédemment ; (3) enfin, cette espèce parasite présente des avantages d'un point de vue expérimental : les sexes et génotypes des individus utilisés peuvent et sont contrôlés en laboratoire et des populations "naturellement" clonales sont à notre disposition. C'est pourquoi, nous nous sommes intéressés à la monogamie chez cet invertébré parasite monogame. Plusieurs questions sont développées durant cette thèse : qui est monogame parmi les Schistosomatidae et pourquoi ? Est-ce que une monogamie sociale et génétique ou sociale et non génétique (i.e. des changements de partenaires sont-ils observés) ? Quels sont les facteurs impliqués dans ces changements de partenaire (dissimilarité entre les partenaires du couple, biais de sex ratio en faveur des males, différences neutres, fonctionnelles et phénotypiques entre les mâles, effet du système immunitaire de l'hôte vertébré) ? C'est par l'association de réflexions et d'expérimentations que nous tentons de répondre à ces questions.

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De, Garine-Wichatitsky Michel de. "Ecologie des interactions hôtes/vecteurs : analyse du système tiques/ongulés sauvages et domestiques en zone tropicale." Montpellier 2, 1999. http://www.theses.fr/1999MON20114.

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Les hotes peuvent-ils eviter les parasites ? dans une perspective ecologique et evolutive, nous avons etudie l'infestation des ongules par des tiques, ainsi que la distribution spatio-temporelle de ces vecteurs et de leurs hotes. Un modele theorique est presente qui relie (1) les niveaux d'infestation des ongules ; a (2) l'utilisation de l'habitat par les ongules ; et (3) l'abondance des tiques dans la vegetation. Les parametres du modele ont ete mesures sur un ranch mixte faune/betail du zimbabwe en fonction des saisons : (1) les niveaux d'infestation sont variables entre les especes d'ongules ; (2) l'utilisation de l'habitat par les ongules differe entre les especes, mais ne semble pas expliquer les variations d'infestation entre especes ou entre individus-hotes ; (3) l'abondance des larves de tiques dans la vegetation revele deux distributions garantissant le contact avec les ongules : une distribution imprevisible dans le temps et l'espace, et donc inevitable ; une distribution previsible, mais inevitable car associee a des ressources indispensables aux hotes (points d'eau et ressources fourrageres). Les strategies eventuelles d'evitement des tiques par les ongules sont abordees en fonction des compromis qu'elles impliquent pour les hotes, de la previsibilite du risque parasitaire, et de l'agregation des parasites a differentes echelles. Les tiques et les maladies a tiques constituent un frein majeur au developpement de l'elevage en zone tropicale. De plus, face a la multiplication des conflits entre la faune et les activites pastorales en afrique (competition pour les paturages et transmission de maladies), les systemes mixtes faune/betail permettent de concilier des objectifs de conservation et de productions animales. Nos resultats sont discutes en relation avec la spatialisation du risque vectoriel, les methodes de lutte contre les tiques, et l'interet d'une etude genetique des vecteurs pour etablir le role de reservoir eventuel de la faune sauvage.

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Sire, Christel. "Ecologie moléculaire des populations de Schistosama mansori parasite du rongeur Rattus rattus et du mollusque Biompharalaria glabrata en Guadeloupe : échelles spatiales et fonctionnelles." Perpignan, 2000. http://www.theses.fr/2000PERP0384.

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Le fonctionnement dynamique et génétique d'un sysème parasite/hôtes/environnement est étudié en relation avec les différentes échelles spatiales (régionale vs locales) et fonctionnelles (populations de parasites adultes chez les hôtes défénitifs vs populations de parasites larvaires chez les hôtes intermédiaires)
In this study, we investigated the genetic and dynamc organisation of a parasite/hosts/environment system, at two different spatial scales (regional vs local), and at two different functional scales (adult parasite populations within intermediate hosts)

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Lion, Sébastien. "Structuration spatiale et évolution des populations." Paris 6, 2007. http://www.theses.fr/2007PA066354.

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Depuis une vingtaine d'années, le rôle de l'auto-structuration spatiale dans les processus évolutifs est devenu un point d'intérêt majeur en écologie évolutive. Parallèlement, le domaine de l'écologie spatiale a connu une véritable révolution avec l'introduction de nouvelles techniques de modélisation prenant en compte explicitement à la fois la structure spatiale et l'individualité. Le but de cette thèse est de comprendre comment l'interaction entre la dynamique écologique spatiale et l'évolution, grâce à une approche théorique qui combine simulations et modèles analytiques. Cette thèse a trois axes principaux. Dans une première partie, nous passons en revue les progrès théoriques que les modèles spatialisés les plus récents ont apportés à notre compréhension de l'évolution, et nous soulignons que la plupart des résultats se comprend mieux dans le cadre théorique plus large de la sélection multi-niveaux et de la sélection de parentèle. Dans un deuxième temps, nous développons un modèle pour l'évolution de populations structurées dans l'espace et en classes. Nous proposons une technique pour calculer la condition d'invasion d'un mutant rare au moyen d'équations de corrélations (ou approximation des paires), et l'appliquons à un modèle d'interactions entre adultes et jeunes. Ce modèle est adapté à l'étude de l'évolution des soins parentaux et du cannibalisme des jeunes, et nous permet de généraliser les conclusions d'études précédentes sur l'évolution de la coopération dans des populations visqueuses. En utilisant une méthodologie qui ne repose pas sur des approximations de la structure spatiale, nous donnons un éclairage sur les pressions de sélection qui s'appliquent sur les soins parentaux et le cannibalisme, et nous montrons qu'une variante de la règle de Hamilton émerge de la dynamique écologique spatiale. Nous montrons aussi que la forme des compromis évolutifs entre les traits démographiques est un facteur crucial qui détermine l'issue de l'évolution dans le modèle spatialisé, et que le rôle des corrélations spatiales d'ordre supérieur à trois peut avoir une importance quantitative subtile, mai
Over the last two decades, the role of spatial self-structuring as a template for evolution has been a focus of increasing attention. At the same time, the field of spatial ecology has seen radical new developments with the advent of new modelling techniques that explicitely take into account both spatial structure and individuality. The aim of this thesis is to try an understand the interplay between spatial ecological dynamics and evolution, through a theoretical approach that uses both simulations and analytical models. The thesis unfolds along three axes. In a first part, we review the theoretical progress that the latest-spatially explicit models have brought to our understanding of evolution, and argue that most results are best understood in the larger framework of multilevel and kin selection. Secondly, we develop an analytical model for the evolution of populations that are structured both in space and in discrete classes. A technique to derive the invasion condition of a rare mutant is proposed using correlation equations (aka pair approximation), and applied to a model of juvenile-adult interactions. This model is adapted to the study of the evolution of parental care and juvenile cannibalism, and allows us to extend previous studies of the evolution of cooperation in viscous populations to altruistic interactions between different classes of individuals. Using a methodology that does not resort to approximations of the spatial structure, we shed light on the selective pressures on parental care and cannibalism, and show we can recover Hamilton's rule and relatedness as emergent properties of the spatial ecological dynamics. We also show that the shape of trade-off curves is crucial in determining the evolutionary outcome in the spatial model, and that in age-structured populations, the evolutionary role of higher-order spatial moments can be very subtle, but quantitatively important. Finally, we study the evolution of dispersal in host-parasite interactions. Evolution of the manipulation of host dispersal behaviour by parasites is shown to depend both on the scale of dispersal and on th

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GERARD, CLAUDIA. "Ecologie d'une interaction durable : schistosoma mansoni/biomphalaria glabrata. dynamique de l'infrapopulation parasite dans l'ecosysteme mollusque, interactions spatiales et energetiques." Paris 6, 1993. http://www.theses.fr/1993PA066373.

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Le systeme s. Mansoni/b. Glabrata est utilise comme modele pour une approche ecologique des interactions ecosysteme hote-infrapopulation parasite. La dynamique des infrapopulations parasites est etudiee pour differentes tailles (age) d'ecosysteme mollusque et pour des nombres varies d'individus fondateurs de l'infrapopulation parasite, en relation avec les contraintes spatiales et energetiques du systeme. Contrainte spatiale. La taille de l'infrapopulation parasite evolue en fonction de l'augmentation de la taille de son biotope (glandes digestive et genitale); des mecanismes de regulation interviennent pour limiter et stabiliser la croissance de l'infrapopulation parasite a sa valeur d'equilibre par rapport a la capacite biotique de l'hote. Les consequences fonctionnelles du mode d'integration spatiale par remplacement du parasite sont analysees au niveau de l'acquisition des ressources de l'hote. Contrainte energetique. Les modifications des traits de vie de l'hote (survie, croissance, fecondite) qui resultent de la contrainte energetique du parasite sur l'hote, sont interpretees en termes de competition par exploitation ou par interference. L'existence d'une manipulation de la physiologie de l'hote par le parasite est demontree: stimulations precoces de la croissance ou de la fecondite selon l'age du mollusque. La valeur adaptative de ces modifications est discutee par rapport a la performance du systeme trematode/mollusque

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Roy, Lise. "Ecologie évolutive d'un genre d'acarien hématophage : approche phylogénétique des délimitations interspécifiques et caractérisation comparative des populations de cinq espèces du genre Dermanyssus (Acari : Mesostigmata)." Phd thesis, AgroParisTech, 2009. http://pastel.archives-ouvertes.fr/pastel-00005531.

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Les acariens microprédateurs du genre Dermanyssus (espèces du groupe gallinae), inféodés aux oiseaux, représentent un modèle pour l'étude d'association lâche particulièrement intéressant : ces arthropodes aptères font partie intégrante du microécosystème du nid (repas de sang aussi rapide que celui du moustique) et leurs hôtes sont ailés. En outre, D. gallinae est une espèce d'importance économique, ce qui rend possible des comparaisons entre colonisation de milieux anthropisés et sauvages. Au début de l'étude, les espèces du groupe gallinae sont très mal délimitées. Les caractères morphologiques utilisés sont variables au sein de l'espèces, voire de la population, très chevauchants entre espèces. Afin de mieux comprendre les exigences écologiques du développement de D. gallinae et d'appréhender ses voies de dissémination, une investigation comparative basée sur des séquences d'ADN entre espèces du groupe gallinae a été adoptée. Un cheminement d'ordre taxinomique a permis de poser les bases nécessaires. Ensuite, l'exploration de certaines caractéristiques écologiques du groupe gallinae en relation avec sa phylogénie (spécificité d'hôte, flexibilité évolutive) a été menée à bien. Une espèce a été décrite, D. apodis, une lignée de D. gallinae constitue aussi une probable espèce inédite et D. longipes regroupe deux entités. Des différences écologiques marquées entre D. gallinae et les autres espèces semblent résulter non seulement de l'activité humaine, mais aussi de caractéristiques intrinsèques. Aujourd'hui, le rôle des flux commerciaux dans la dispersion de D. gallinae en élevage de pondeuses s'avère primordial, au moins en France, celui des oiseaux sauvages presque nul.

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Rouxel, Mélanie. "Ecologie et évolution de l’interaction Plasmopara viticola / Vitis spp. et évaluation des risques de contournement de la résistance de la vigne au mildiou." Thesis, Bordeaux 2, 2012. http://www.theses.fr/2012BOR22023/document.

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La compréhension du processus d’adaptation des populations de parasites à leur plante-hôte est une question fondamentale en écologie évolutive. C’est également un enjeu majeur de recherche finalisée qui a des retombées pour la protection des cultures. L’oomycète Plasmopara viticola, agent causal du mildiou de la vigne, attaque les espèces du genre Vitis. Dans un contexte où l’enjeu principal des programmes d’amélioration est la durabilité des résistances, des connaissances nouvelles sur l’écologie et l’évolution de l'interaction entre le parasite et son hôte sont nécessaires afin d’évaluer le potentiel du mildiou à surmonter ces résistances. Dans ma thèse, je me suis intéressée au rôle de la plante-hôte comme facteur d’évolution des populations de mildiou, en posant cette question à différentes échelles évolutives : (i) dans le bassin d’origine du pathogène (Amérique du Nord), j’ai cherché à évaluer le degré de spécialisation du parasite sur sa gamme d’hôtes sauvages et cultivés; (ii) en Europe, où le mildiou de la vigne a été introduit récemment, j’ai étudié l’évolution des populations de mildiou soumis à la pression de sélection des résistances des nouvelles variétés de vigne. Pour comprendre la spécialisation plante-hôte dans ce pathosystème où plusieurs espèces cryptiques ont été identifiées, nous avons réalisé des tests d’inoculations croisées entre espèces hôtes (Vitis spp.) et agent pathogène (P. viticola). Les données phénotypiques et morphologiques apportent les preuves d’une spécialisation plante-hôte au sein des populations de P. viticola : les espèces A et D de mildiou sont spécialisées sur leur plante-hôte, tandis que le processus de spécialisation est en cours pour les espèces B et C. Même si aucune différenciation génétique n’a été montrée au sein de l’espèce C, il existe deux groupes distincts au sein de l’espèce B. Les isolats du compartiment cultivé sont en moyenne plus agressifs que les isolats issus des vignes sauvages, indiquant une adaptation des isolats cultivés sur leur plante hôte. A partir d’un large échantillonnage, nous avons étudié la distribution des espèces de mildiou sur leurs plantes-hôtes sauvages et cultivées. Ce travail a permis d’identifier une nouvelle espèce cryptique et a confirmé la spécialisation plante-hôte. En Europe, nos résultats montrent que le déploiement limité de variétés à résistantes partielles a conduit à des modifications des populations de mildiou: apparition d’isolats virulents (i.e. contournant un QTL majeur de résistance), et augmentation de l’agressivité sur Vitis vinifera. Dans le but de comprendre les mécanismes à l’origine de la spécialisation et du contournement des résistances, nous nous sommes intéressés au répertoire d’effecteurs du parasite. Une centaine d’effecteurs candidats ont été identifiés en utilisant les données disponibles sur le génome de P. viticola. L’analyse du polymorphisme de 32 candidats sur une sélection d’isolats montre que trois d’entre eux évoluent sous sélection positive. Ces résultats soulignent l’importance de la plante-hôte comme facteur de diversification des populations de l’agent pathogène et révèlent que le mildiou s’adapte rapidement aux résistances de la vigne. Il est désormais nécessaire de mieux appréhender le déploiement des résistances de la vigne afin qu’elles puissent être durables
Understanding the process of adaptation of parasite populations to their host-plant is a key issue in evolutionary ecology. It is also a major subject in applied research that has implications for crop protection. The oomycete Plasmopara viticola, the causal agent of downy mildew, attacks the species of the Vitis genus. In a context where the main concern of the breeding programs is the durability of resistance, new knowledge about the ecology and evolution of the interaction between parasite and host is needed in order to evaluate the potential of downy mildew to overcome the resistance. In my thesis, I addressed the role of the host-plant as an evolutionary factor for downy mildew populations, by asking this question at two different evolutionary scales: (i) in the pathogen region of origin (North America) I assessed the degree of specialization of the parasite on its wild and cultivated host range (ii) in Europe, where downy mildew has been introduced recently, I studied the evolution of downy mildew populations subject to the selection pressure imposed by resistant grapevine varieties. To understand the host-plant specialization in this pathosystem, where several cryptic species have been identified, we performed cross inoculations between different host (Vitis spp.) and pathogen (P. viticola) species. Morphological and phenotypic data provide evidence of host-plant specialization in P. viticola populations: downy mildew species A and D are specialized on their host-plant, while the specialization process is ongoing for species B and C. Although no genetic differentiation has been shown inside species C, there are two distinct groups within species B. Isolates from the cultivated compartment are on average more aggressive than isolates from wild vines, indicating an adaptation of isolates growing on cultivated host-plants. Finally, a large-scale study of the distribution of downy mildew species on both their wild and cultivated host-plants resulted in the identification of a new cryptic species and confirmed the host-plant specialization. In Europe, our results show that the limited deployment of resistant varieties has led to changes in downy mildew populations: emergence of virulent isolates (i.e. breakdown of a major QTL for resistance), and increased aggressiveness on Vitis vinifera. In order to understand the mechanisms at the origin of specialization and resistance breakdown, we examined the parasite’s effector repertoire. Over one hundred effector candidates were identified using available data on the P. viticola genome. The polymorphism of 32 candidate genes revealed that three of them evolve under positive selection. Our results reveal the strong ability of downy mildew to adapt to its host plant and to plant resistance. They should be taken into account when devising strategies for the deployment of grapevine resistances in order to guarantee their durability

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Boyer, Séverine. "Ecologie du copépode calanoïde Paracartia grani : implication dans le cycle de vie du parasite Marteilia refringens dans la lagune de Thau." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20147/document.

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Au cours de cette étude, le cycle de vie de Paracartia grani, un copépode calanoïde appartenant à la famille des Acartiidae, a été déterminé dans la lagune de Thau. En effet, ce copépode aurait une implication dans le cycle de vie du parasite Marteilia refringens, affectant les productions de bivalves. Un suivi bimensuel de la communauté mésozooplanctonique effectué sur deux ans à une station fixe dans la lagune a permis de déterminer que P. grani est l'espèce d'Acartiidae dominante en été. Son cycle de vie se compose de deux phases : une phase pélagique d'avril à janvier, et une phase benthique de février à début avril durant laquelle l'espèce subsiste dans le sédiment sous la forme d'œufs de diapause. L'analyse de la structure de la population (spectre de taille, contribution des stades de développement et sexe ratio) a permis de déterminer que 9 générations se succédaient pendant l'année. L'étude de l'influence de 3 paramètres environnementaux (température, salinité et concentration en chlorophylle a) sur la dynamique de ponte de l'espèce a révélé que la production d'œufs de P. grani était principalement régie par la température et que l'augmentation rapide de celle-ci au printemps permettait de déclencher l'éclosion des œufs de diapause. Le second objectif de cette étude s'est attaché à décrire la dynamique du parasite M. refringens chez P. grani et les bivalves Mytilus galloprovincialis et Ruditapes decussatus dans la lagune de Thau. Des analyses en histologie et hybridation in situ ont permis de décrire les différentes formes du parasite chez ces 3 espèces. La recherche de M. refringens par PCR chez les copépodites de P. grani a révélé la présence d'ADN de parasite de juin à novembre, période à laquelle de nouvelles moules apparaissent infectées. Les expériences de mesure de l'efficacité de rétention des différents stades de développement de P. grani par la moule ont permis de montrer que tous les stades de développement peuvent être impliqués dans le cycle de vie de M. refringens, en particulier les œufs du copépode qui ont par ailleurs présentés des résultats positifs en PCR. Notre étude a ainsi permis de préciser les interactions entre copépode, parasite et moules mais n'a pas permis d'élucider complètement le cycle de Marteilia refringens. Des questions restent posées concernant notamment les voies de transmission du parasite du copépode vers les moules et concernant l'impact potentiel du parasite sur le copépode lui-même
In this study, the life cycle of Paracartia grani, a calanoid copepod belonging to the Acartiidae family was determined in Thau lagoon. Indeed, the copepod involvement in the life cycle of the parasite Marteilia refringens affecting the bivalves production is suspected. Mesozooplanktonic community was monitored twice a month over two years at a fixed station in the lagoon. Sampling has identified P. grani as the acartiid dominant species in summer. From April to January, the copepod is found in the water column while from February to early April it remains in the sediment as diapausing eggs. The analysis of the population structure (size spectrum, contribution of developmental stages and sex ratio) has revealed that there are 9 generations per year. The study of the influence of three environmental parameters (temperature, salinity and chlorophyll a concentration) on the dynamic nesting species indicated that P. grani egg production was mainly governed by temperature and its rapid increase in spring could trigger the hatching of diapause eggs.The second objective of this study aimed to describe the dynamics of the parasite M. refringens in P. grani, and in the bivalves Mytilus galloprovincialis and Ruditapes decussatus in the Thau lagoon. Histological and in situ hybridization analysis allowed describing the different forms of the parasite in these three species. Research of M. refringens by PCR in P. grani copepodites revealed that the parasite DNA presence in the copepod from June to November, when new mussels appeared infected. Experiments to measure the retention efficiency of the different stages of development of P. grani by mussels have shown that all developmental stages could be involved in M. refringens life cycle, especially copepod eggs that have also shown positive results by PCR. Our study has allowed clarifying interaction between copepods, parasites and mussels but not elucidate completely M. refringens life cycle. Questions remain especially regarding way of transmission of parasite from copepods to mussels and the potential impact of the parasite on the copepod itself

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Pereira, Felipe Bisaggio. "Estrutura da comunidade de helmintos associados ao lagarto Tropidurus torquatus (Squamata: Tropiduridae) em uma área de afloramento rochoso no distrito de Toledos, Juiz de Fora, MG." Universidade Federal de Juiz de Fora (UFJF), 2010. https://repositorio.ufjf.br/jspui/handle/ufjf/3017.

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A comunidade parasitária do lagarto Tropidurus torquatus em uma área de campo rupestre localizada no estado de Minas Gerais, sudeste do Brasil, foi estudada. Dos 110 hospedeiros analisados, 92 (83,6%) estavam infectados. Foram encontradas cinco espécies de helmintos, três de nematóide: Physaloptera lutzi, Parapharyngodon sp. e Oswaldofilaria sp., uma espécie de cestóide e um cistacanto não identificados. Apenas as espécies de nematóides apresentaram dados suficientes para analises ecológicas, sendo P. lutzi a espécie mais prevalente (67,3%) e com maior intensidade parasitária (4,86±4,85). Somente para Oswaldofilaria sp. foram encontradas diferenças significativas na prevalência e intensidade parasitária entre hospedeiros fêmeas e machos, esses últimos apresentando os maiores valores. A intensidade parasitária total e de P. lutzi também diferiram entre os sexos de hospedeiros com machos apresentando os maiores valores. O tamanho corporal do hospedeiro correlacionou-se de forma positiva com a intensidade de infecção de todas as espécies de nematóides. A sazonalidade local não influenciou de forma significativa a estrutura da comunidade componente de parasitos estudada. Aspectos do hospedeiro como dieta, dimorfismo sexual e comportamento (territorialiasmo e forrageamento) representaram importantes fatores na determinação da estrutura dessa comunidade de helmintos. De maneira geral, a comunidade parasitária apresentou baixa riqueza de espécies e um caráter não interativo, características comuns em comunidades parasitárias de répteis como hospedeiros.
The helminth community of the lizard Tropidurus torquatus from a rocky outcrop located in Minas Gerais state, southeast Brazil, was studied. Ninety two of the one hundred ten individuals examined (83,6%) harbored helminths. A total of five helminth species were found, tree nematodes: Physaloptera lutzi, Parapharyngodon sp. and Oswaldofilaria sp., one cestode species and one acanthocaphalan cystacanth not identified. Only nematode species had sufficient data to perform ecological analysis with Physaloptera lutzi showing the highest prevalence (67,3%) and mean intensity (4,86±4,85). Prevalence and intensity of infection between males and females hosts differed only for Oswaldofilaria sp., with males showing the highest values. Total and P. lutzi intensity of infection were different among males and females hosts, with males showing the highest values. The host body size was positively related to intensity of infection for all nematode species. Local seasonality had no influence in the helminth community structure. Host diet, sexual dimorphism and behavior (territorialism, forage strategy) represented important factors in the structuring of this parasite community. In general lines, the helminth community was species poor and non interactive, representing a typical community structure found in herps hosts.

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Boëte, Christophe. "Ecologie évolutive de la réponse de mélanisation chez le moustique Aedes aegypti et utilisation des moustiques génétiquement modifiés pour le contrôle du paludisme." Paris 6, 2003. http://www.theses.fr/2003PA066028.

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Cellier-Holzem, Elise. "Ecologie évolutive de la malaria aviaire : approches expérimentales des relations entre Plasmodium relictum et le canari domestique." Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00665065.

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L'étude des interactions hôtes/parasites est actuellement un thème de recherche incontournable des sciences de l'évolution. Une des questions majeures soulevée par ces études est de comprendre pourquoi certains parasites provoquent des maladies mortelles, alors que d'autres restent relativement bénins pour leurs hôtes. Dans ce défi que tentent de relever les biologistes de l'évolution mais également les sciences médicales, nous avons choisi de nous intéresser à la malaria aviaire, et plus précisément à son représentant le plus commun dans les populations naturelles d'oiseaux : Plasmodium relictum. En procédant à des infections expérimentales de canaris domestiques (Serinus canaria), nous avons voulu comprendre quels facteurs liés aux caractéristiques du parasite et de l'oiseau (au niveau de l'individu ou de la population) pouvaient influencer la virulence de Plasmodium relictum. Nous avons ainsi pu mettre en évidence que des facteurs, tels que le passé infectieux de l'hôte, la dose de parasites reçue, la prévalence de ces derniers dans la population d'oiseaux ou bien encore les interactions sociales entre individus, pouvaient moduler les coûts d'une telle infection. La virulence est un trait composite qui dépend, certes, de l'exploitation de l'hôte par les parasites mais également de la réponse immunitaire de ce dernier contre l'infection. Nous avons pu le vérifier dans notre système expérimental en utilisant une approche immuno-écologique. Nous nous sommes enfin intéressée aux conditions favorisant l'évolution de la virulence : ce qui est essentiel pour comprendre l'émergence ou la réémergence de maladies infectieuses et pour développer des stratégies de contrôle de ces maladies.

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Monjot, Arthur. "Les eucaryotes unicellulaires dans les écosystèmes lacustres : de la diversité fonctionnelle aux interactions hôte-parasites." Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0109.

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Au cours des dernières décennies, notre compréhension de la diversité microbienne dans l'environnement a beaucoup progressé notamment avec l'avènement des méthodes de séquençage de nouvelle génération et les approches « -omics ». Leur application a notamment permis de s'affranchir des approches de mise en culture ne contribuant qu'à une évaluation partielle et orientée de la diversité microbienne. Le métabarcoding, basé sur l'étude d'un marqueur unique et ubiquiste, est la méthode la plus utilisée pour l'analyse de la diversité car elle permet une évaluation assez exhaustive des espèces présentes dans un écosystème. En milieu aquatique, elle a en effet permis la mise en évidence d'une diversité considérable et insoupçonnée d'eucaryotes unicellulaires. Toutefois cette approche, essentiellement descriptive, ne permet pas de déterminer la physiologie ni de comprendre le rôle de ces microorganismes dans les écosystèmes. D'autres méthodes, telles que la métatranscriptomique, offrent la possibilité d'étudier leur potentiel métabolique et d'en évaluer les variations en fonction de paramètres environnementaux. Néanmoins, ces approches de séquençage haut débit conduisent à la production d'une quantité colossale de séquences environnementales dont la majeure partie reste inconnue. Afin d'étudier le lien diversité-fonction au sein des eucaryotes unicellulaires et ainsi mieux comprendre leur rôle dans les réseaux trophiques lacustres, largement sous-étudiés en comparaison aux écosystèmes marins, plusieurs approches ont été utilisées.Du métabarcoding couplé à une étude de traits morpho-physio-phénotypiques, de la métatranscriptomique ainsi qu'une méthodologie basée sur l'isolement et la caractérisation de couples hôte-parasites (séquençage et hybridation in situ), ont été réalisés à partir d'échantillons lacustres (Pavin, méromictique ; Aydat, dimictique). Ces analyses ont révélé l'importante diversité des photo-osmo-phago-mixotrophes et des parasites tout en mettant en évidence les fortes variations saisonnières qu'ils subissent dans le mixolimnion du lac Pavin. Il semblerait, par exemple, que les périodes de brassage profitant aux communautés hôtes photosynthétiques favorisent le développement et la dissémination de champignons parasites notamment par la surexpression de gènes impliqués dans la phototaxie des zoospores et dans les métabolismes lipidiques. Parmi ces champignons parasites, les microsporidies sont des acteurs nouvellement identifiés dans les réseaux trophiques aquatiques. Nous avons en effet découvert avec une forte prévalence (42,5%) dans le lac d'Aydat, une association hôte-parasites entre une potentielle nouvelle espèce de microsporidie et une espèce de rotifère.Une importante biosphère rare a également été mise en évidence dans le monimolimnion anoxique du lac Pavin, caractérisée par de nombreux saprotrophes surexprimant des gènes liés aux métabolismes du soufre, du nitrate et de dégradation de la matière organique. Les métabolismes caractéristiques d'organismes de différents modes trophiques ont également été étudiés en réalisant une étude basée sur la construction de réseaux de similarité de séquences protéiques. Tout en caractérisant pour la première fois une majorité de séquences inconnues (>40%), nous avons révélé la proximité génétique de protéines entre microorganismes hétérotrophes et photo-osmo-phago-mixotrophes et entre saprotrophes et parasites, ainsi qu'une redondance fonctionnelle relative des métabolismes primaires. En revanche, nous avons identifié près d'un million de protéines caractéristiques d'un seul groupe fonctionnel qui, pour certaines, représentent de réelles perspectives d'étude des voies métaboliques impliquées dans les interactions hôte-parasites
Over the last few decades, our understanding of microbial diversity in the environment has advanced considerably, particularly with the advent of next-generation sequencing methods and -omics approaches. These methods have allowed for a more comprehensive evaluation of microbial diversity compared to traditional culture-based approaches. The most commonly used method for analyzing diversity is metabarcoding, which is based on the study of a unique and ubiquitous marker. This method has revealed a considerable and unsuspected diversity of microbial eukaryotes in aquatic environments. However, this approach is mainly descriptive and does not allow for the determination of the physiology or understanding of the role of these microorganisms in ecosystems. Other methods, such as metatranscriptomics, offer the possibility of studying their metabolic potential in relation to environmental parameters. Nevertheless, these high-throughput sequencing approaches lead to the production of a vast quantity of environmental sequences, most of which remain unknown. To better understand the diversity-function link within microbial eukaryotes and their role in lacustrine trophic networks, several approaches have been used.Metabarcoding coupled with a study of morpho-physio-phenotypic traits, metatranscriptomics and a methodology based on the isolation and characterization of host-parasite pairs (sequencing and in situ hybridization), were carried out on lake samples (Pavin, meromictic; Aydat, dimictic). These analyses revealed the high diversity of photo-osmo-phago-mixotrophs and parasites, while also highlighting the strong seasonal variations they undergo in the mixolimnion of lake Pavin. For example, periods of mixing benefiting photosynthetic host communities favor the development and dissemination of parasitic fungi, notably through the overexpression of genes involved in zoospore phototaxis and lipid metabolism. Among these parasitic fungi, Microsporidia are newly identified players in aquatic food webs. Indeed, we discovered a high prevalence (42.5%) host-parasite association between a potential new species of Microsporidia and a species of rotifer in lake Aydat. An important rare biosphere has also been highlighted in the anoxic monimolimnion of Lake Pavin, characterized by numerous saprotrophs overexpressing genes related to sulfur, nitrate, and organic matter degradation metabolisms. The characteristic metabolisms of organisms of different trophic modes have also been studied by constructing protein sequences similarity networks.While characterizing the majority of unknown sequences for the first time (>40%), we have revealed the genetic proximity of proteins between heterotrophic and photo-osmo-phago- mixotrophic microorganisms and between saprotrophs and parasites, as well as a relative functional redundancy of primary metabolisms. On the other hand, we have identified nearly one million proteins characteristic of a single functional group, which, for some, represent real prospects for studying the metabolic pathways involved in host-parasite interactions

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Prior, Kimberley Faith. "The evolutionary ecology of circadian rhythms in malaria parasites." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/29562.

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Biological rhythms are thought to have evolved to enable organisms to organise their activities according to the Earth’s predictable cycles, but quantifying the fitness advantages of rhythms is challenging and data revealing their costs and benefits are scarce. More difficult still is explaining why parasites that exclusively live within the bodies of other organisms have biological rhythms. Rhythms exist in the development and traits of parasites, in host immune responses, and in disease susceptibility. This raises the possibility that timing matters for how hosts and parasites interact and, consequently, for the severity and transmission of diseases. Despite their obvious importance in other fields, circadian rhythms are a neglected aspect of ecology and evolutionary biology. The ambitions of this thesis are to integrate chronobiology, parasitology and evolutionary theory with mathematical models to obtain a greater understanding about how and suggest why malaria parasites have rhythms as well as the effect of infection on host rhythms. First, I identify how malaria parasites lose their developmental rhythms in culture, when they lack any potential time cues from the host. Next, I characterise parasite rhythms inside the mammalian host in terms of synchrony and timing and demonstrate there is genotype by environment interactions for characteristics of parasite rhythms. Then, I investigate the effect that parasite infection has on host rhythms and show there is variation between parasite genotypes in their effect on host locomotor activity and body temperature rhythms during infections. Finally, I explore which host rhythms may be driving parasite synchrony and timing and demonstrate the importance of peripheral host rhythms for the timing of malaria parasite developmental rhythms. The data presented here provides novel and important information on the role of rhythms during disease and opens up a new arena for studying host-parasite coevolution.

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O'Brien, Chris. "Appreciating the Importance of Parasites: Analyzing and Understanding the Ecology of Parasite-Host Interactions." Diss., The University of Arizona, 2008. http://hdl.handle.net/10150/194212.

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There is a growing interest in the nature of parasite-host interactions, the role these relationships play in ecological communities, and how human activities alter these associations. Furthermore, because inference about these interactions is usually gained by methods of statistical hypothesis testing, additional importance should be placed on the analysis and interpretation of parasite-host interactions. In this dissertation I address these ideas in three separate but interrelated studies with the three following questions: 1) How do two parasites with complex life-cycles alter the behavior of a novel amphipod host, and how do host and non-host predators respond to infected amphipod prey? In contrast to other studies, I found that two parasites of an endemic amphipod at Montezuma Well had little affect on their amphipod host, and that these associations had little affect on predation rates by both host and non-host predators. Results from this study underscore the importance of further investigating novel parasite-host interactions and placing them in their phylogenetic and evolutionary context. 2) Does human recreation affect spatial patterns of infection in an otherwise natural ecosystem? This study demonstrates that human visitors to Montezuma Castle National Monument alter patterns of waterfowl space use that in turn affect spatial patterns of disease in invertebrate hosts. This is the first study to document such an effect, and I discuss the important implications of this finding. 3) How is hypothesis testing applied in studies of wildlife disease, what conclusions can we make about the relative usefulness of these methodologies, and how can the analysis and interpretation of wildlife disease studies be improved? In this final study I conducted a literature review, computed statistical power for methodologies used in the literature, and re-analyzed published data to provide an example of the advantages of my suggested approach. I conclude that many studies report findings using methods that could be more informative and some studies may lack statistical power, demonstrating the importance of using prospective power analysis in the design of future studies. Furthermore, using statistical techniques that estimate the observed effect size can aid in increasing information transfer in studies of wildlife disease.

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Lise, Roy. "Ecologie évolutive d'un genre d'acarien hématophage : approche phylogénétique des délimitations interspécifiques et caractérisation comparative des populations de cinq espèces du genre Dermanyssus (Acari : Mesostigmata)." Phd thesis, INAPG (AgroParisTech), 2009. http://tel.archives-ouvertes.fr/tel-00661327.

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Les acariens microprédateurs du genre Dermanyssus (espèces du groupe gallinae), inféodés aux oiseaux, représentent un modèle pour l'étude d'association lâche particulièrement intéressant : ces arthropodes aptères font partie intégrante du microécosystème du nid (repas de sang aussi rapide que celui du moustique) et leurs hôtes sont ailés. En outre, D. gallinae est une espèce d'importance économique, ce qui rend possible des comparaisons entre colonisation de milieux anthropisés et sauvages. Au début de l'étude, les espèces du groupe gallinae sont très mal délimitées. Les caractères morphologiques utilisés sont variables au sein de l'espèce, voire de la population, très chevauchants entre espèces. Afin de mieux comprendre les exigences écologiques du développement de D. gallinae et d'appréhender ses voies de dissémination, une investigation comparative basée sur des séquences d'ADN entre espèces du groupe gallinae a été adoptée. Un cheminement d'ordre taxinomique a permis de poser les bases nécessaires. Ensuite, l'exploration de certaines caractéristiques écologiques du groupe gallinae en relation avec sa phylogénie (spécificité d'hôte, flexibilité évolutive) a été menée à bien. Une espèce a été décrite, D. apodis, une lignée de D. gallinae constitue aussi une probable espèce inédite et D. longipes regroupe deux entités. Des différences écologiques marquées entre D. gallinae et les autres espèces semblent résulter non seulement de l'activité humaine, mais aussi de caractéristiques intrinsèques. Aujourd'hui, le rôle des flux commerciaux dans la dispersion de D. gallinae en élevage de pondeuses s'avère primordial, au moins en France, celui des oiseaux sauvages presque nul.

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Vieira, Vivian Suane de Freitas. "Metazo?rios parasitos de Pimelodus spp. e estrutura da comunidade parasit?ria de Pimelodus maculatus (Siluriformes: Pimelodidae) coletados em duas bacias hidrogr?ficas do Brasil." Universidade Federal Rural do Rio de Janeiro, 2016. https://tede.ufrrj.br/jspui/handle/jspui/1199.

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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES
A list of metazoan species associated to Pimelodus Lac?p?de, 1803 genus has been prepared in this work. The total of 516 records in 10 host species of genus was compiled. Were included in the list of new geographic records monogeneans parasites of Pimelodus maculatus Lac?p?de, 1803 collected from Midwest, Southeast and South of Brazil. New morphological data of Cucullanus pinnai pinnai Travassos, Artigas & Pereira, 1928, parasite of P. maculatus collected in the Guandu river, in the State of Rio de Janeiro have been reported. This work noted that the position of the excretory pore and deirids of the specimens are at the level or posterior to the oesophagus- intestine junction in the most specimens and gubernaculums size is greater than in other previously studied of C. pinnai pinnai. Nematodes were studied using light and scanning electron microscopy (SEM) and differential interference contrast (DIC) and analyzes confirmed morphological details of the cephalic region and the caudal papillae that species. Comparative study of parasitic communities of P. maculatus was also performed. 50 specimens of the P. maculatus were collected from Guandu river, in the State of Rio de Janeiro and others 50 from Mogi-Gua?? river, State of S?o Paulo. In the samples from Guandu river were identified the following species: Ameloblastella paranaensis Fran?a, Isaac, Pavanelli & Takemoto, 2003 (P= 8%; MI= 1,0?0,0); A. satoi Monteiro, Kritsky, Brasil-Sato, 2010 (P= 8%; MI= 1,0?0,0); Demidospermus bidiverticulatum Suriano & Incorvaia, 1995 (P= 8%; MI= 1,0?0,0); D. paravalenciennesi Guti?rrez & Suriano, 1992 (P=90%; MI=14,77?5,04), D. uncusvalidus Guti?rrez & Suriano, 1992 (P=90%; MI=12,37?4,86), D. valenciennesi Guti?rrez & Suriano, 1992 (P=56%; MI=6,06?3,95) e Cucullanus pinnai pinnai Travassos, Artigas & Pereira, 1928 (P=64%; MI=3,28?4,87). In the rio Mogi-Gua?? the parasites identified were: Ameloblastella paranaensis (P= 8%; MI= 1,0?0,0), Ameloblastella satoi (P= 8%; MI= 1,0?0,0), Demidospermus paravalenciennesi (P=86%; MI=18,58?10,79), D. uncusvalidus (P=84%; MI=16,73?7,74), D. valenciennesi (P=52%; IM=6,84?4,55) e Cucullanus pinnai pinnai (P= 44%; MI= 3,88?4,87). The females of P. maculatus had higher weight and length of males in both samples. The sex and o length of the hosts did not influence the level of parasitism. Positive correlation was observed between weight of host and abundance of D. uncusvalidus only in the sample of the Guandu river. Aggregate distribution was observed in all the prevalent species of metazoan parasites of P. maculatus in the two localities. D. paravalenciennesi showed a higher frequency of dominance and relative dominance in the samples of Guandu river and D. uncusvalidus in the samples of Mogi-Gua?? river. The results of the qualitative similarity index Jaccard (CJ) and quantitative Sorensen (CS) within the collected samples were homogenea. The Jaccard index indicated heterogeneity while Sorensen index indicated homogeneity between samples. The results demonstrated that the relationship between parasites and their hosts are constant even in different river basins.
Uma lista de esp?cies de metazo?rios associados ao g?nero Pimelodus Lac?p?de, 1803 foi elaborada neste trabalho. O total de 516 registros em 10 esp?cies de hospedeiros do g?nero foi compilado. Foram inclu?dos na lista novos registros de geogr?ficos de parasitos monogen?ticos de Pimelodus maculatus Lac?p?de, 1803 coletados nas regi?es Centro-oeste, Sudeste e Sul do Brasil. Novos dados morfol?gicos de Cucullanus pinnai pinnai Travassos, Artigas & Pereira, 1928, parasito de P. maculatus coletado no rio Guandu, no Estado do Rio de Janeiro foram relatados. Foi observado que a posi??o do poro excretor e deir?deos nos esp?cimes estudados s?o posteriores ao final do es?fago na maioria dos esp?cimes e o tamanho do gubern?culo ? maior do que em outros de C. pinnai pinnai estudados anteriormente. Os nematoides foram estudados utilizando microscopia eletr?nica de varredura (MEV) e contraste interferencial de fase (DIC) e as an?lises confirmaram detalhes morfol?gicos da regi?o cef?lica e as papilas caudais dessa esp?cie. Estudo comparativo das comunidades parasit?rias de P. maculatus tamb?m foi realizado. Foram coletados 50 esp?cimes de P. maculatus no rio Guandu, no Estado do Rio de Janeiro e outros 50 exemplares no rio Mogi-Gua??, no Estado de S?o Paulo, foram examinados para o estudo de sua parasitofauna, no per?odo de maio ? dezembro de 2012. No rio Guandu foram coletadas as seguintes esp?cies: Ameloblastella paranaensis Fran?a, Isaac, Pavanelli & Takemoto, 2003 (P= 8%; IM= 1,0?0,0); A. satoi Monteiro, Kritsky, Brasil-Sato, 2010 (P= 8%; IM= 1,0?0,0); Demidospermus bidiverticulatum Suriano & Incorvaia, 1995 (P= 8%; IM= 1,0?0,0); D. paravalenciennesi Guti?rrez & Suriano, 1992 (P=90%; IM=14,77?5,04), D. uncusvalidus Guti?rrez & Suriano, 1992 (P=90%; IM=12,37?4,86), D. valenciennesi Guti?rrez & Suriano, 1992 (P=56%; IM=6,06?3,95) e Cucullanus pinnai pinnai Travassos, Artigas & Pereira, 1928 (P=64%; IM=3,28?4,87). No rio Mogi-Gua?? os parasitos identificados foram: Ameloblastella paranaensis (P= 8%; IM= 1,0?0,0), Ameloblastella satoi (P= 8%; IM= 1,0?0,0), Demidospermus paravalenciennesi (P=86%; IM=18,58?10,79), D. uncusvalidus (P=84%; IM=16,73?7,74), D. valenciennesi (P=52%; IM=6,84?4,55) e Cucullanus pinnai pinnai (P= 44; IM= 3,88?4,87). As f?meas de P. maculatus apresentaram peso e comprimento maiores que dos machos nas duas amostras. O sexo e o comprimento dos hospedeiros n?o influenciaram o n?vel de parasitismo. Correla??o positiva foi observada entre o peso e a abund?ncia de D. uncusvalidus somente na amostra do rio Guandu. Foi observada distribui??o agregada de todas as esp?cies mais prevalentes de metazo?rios parasitos de P. maculatus nas duas bacias de coleta. D. paravalenciennesi apresentou maior freq??ncia de domin?ncia e domin?ncia relativa no rio Guandu e D. uncusvalidus no rio Mogi-Gua??. Os resultados dos ?ndices de similaridade qualitativa de Jaccard (CJ) e quantitativa de Sorensen (CS) dentro das amostras coletadas demonstraram homogeneidade. O ?ndice Jaccard indicou heterogeneidade e o ?ndice de Sorensen indicou homogeneidade entre as amostras. Os resultados demonstram que o relacionamento entre parasitos e seus hospedeiros s?o constantes, mesmo em diferentes bacias hidrogr?ficas.

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Bichet, Coraline. "Ecologie évolutive de la malaria aviaire : effets des caractéristiques de l'hôte et de l'environnement." Phd thesis, Université de Bourgogne, 2012. http://tel.archives-ouvertes.fr/tel-00907956.

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L'étude des interactions hôtes-parasites est devenue un thème de recherche incontournable pour les sciences de l'évolution. Cette coévolution complexe dépend de nombreux compromis évolutifs et peut être grandement influencée par les facteurs environnementaux. Nous nous proposons ici d'étudier les interactions hôtes-parasites à plusieurs échelles, à travers des approches expérimentales et des études en populations naturelles, en étudiant les parasites de la malaria aviaire. Dans un premier temps, nous nous sommes intéressés à l'influence des caractéristiques de l'hôte et notamment au système immunitaire. Le système immunitaire est bénéfique pour l'hôte dans sa lutte contre le parasite, mais peut également engendrer des coûts immunopathologiques. Des traits d'histoire de vie, comme l'âge ou le statut social peuvent modifier la parasitémie au sein des hôtes, sans toutefois avoir d'effet sur la prévalence. Dans un second temps, l'effet de certains facteurs environnementaux a été évalué au sein des interactions hôtes-parasites. La température et la contamination en métaux lourds ont un effet sur la prévalence dans les populations, mais n'affectent pas la parasitémie. Au cours de cette thèse, nous avons également montré l'influence directe des parasites sanguins sur la structure génétique des populations hôtes, notamment au niveau des gènes du CMH.

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22

Smar, Matt. "The ecology of Protocalliphora (Diptera:Calliphoridae) parasitism of two cavity nesting passerine birds in southwestern Québec." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22806.

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The ecology of Protocalliphora parasitism was studied for a two-year period in two species of cavity nesting passerine birds breeding in southwestern Quebec, the eastern bluebird (Sialia sialis Linnaeus) and the tree swallow (Tachycineta bicolor Vieillot). Both species occupied next boxes in open field habitats. Nests were parasitized primarily by Protocalliphora sialia Shannon and Dobroscky.
The relationship between the number of Protocalliphora larvae per nest and selected nesting variables was examine for the two species. The variables included hatching date of the host young, nest material volume, number of fledglings, and percent canopy cover above the nest box. In bluebirds, the number of larvae per nest was significantly correlated with nest material volume in 1989 and number of fledglings in 1990. In tree swallows, the number of larvae per nest was significantly correlated with hatching date and number of fledglings in 1989.
Information on reproduction in Protocalliphora was obtained. Gravid flies were captured in active nests up to the last end of the second week of the nestling period. P. sialia was determined to be at last bivoltine through mark, release, and recapture studies. It was determine that nulliparous P. sialia can complete egg development within 9 or 10 days after eclosion. The practicality of a new Protocalliphora trapping technique and a mark, release, and recapture technique was demonstrated. (Abstract shortened by UMI.)

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Alba, Menendez Annia. "Comparative biology of susceptible and naturally- resistant Pseudosuccinea columella snails to Fasciola hepatica (Trematoda) infection in Cuba : ecological, molecular and phenotypical aspects." Thesis, Perpignan, 2018. http://www.theses.fr/2018PERP0055/document.

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Pseudosuccinea columella est un des principaux hôtes intermédiaires de Fasciola hepatica, un trématode cosmopolite infectant l’Homme et les animaux domestiques et sauvages, et transmis par des mollusques d’eau douce. L’existence exclusive à Cuba de populations de P. columella qui sont sensibles et naturellement résistantes (encapsulation hémocytaire du parasite) à l’infection par F. hepatica offre un modèle Mollusque-Trématode très intéressant en termes de biologie évolutive, de santé humaine et de stratégies de contrôle vectorielle. L’étude des aspects écologiques, moléculaires et phénotypiques est essentielle pour comprendre les particularités de ce système. Ainsi, nos résultats ont montré que les mollusques sensibles et résistants partagent des exigences écologiques similaires mais chez les résistants la distribution est limitée aux localités avec des eaux acides et peu dures (pH/dureté totale (DT), 6-6.5/4°-10°d) et une richesse des communautés de mollusques très faible, ceci semblant indiquer coût élevé à la résistance. La comparaison de traits d’histoire de vie en laboratoire a permis de confirmer une haute tolérance aux variations de pH/DT de l’eau chez les mollusques résistants mais a montré également une diminution du potentiel reproductif des souches résistantes par rapport aux sensibles. Sur la base de ces observations, des approches «omiques» comparatives ont été entreprises entre souches sensibles et résistantes. Ce travail de thèse nous a aidé à comprendre les particularités de ce modèle hôte-parasite, mais présente également une avancée en termes d’utilisation de la résistance de P. columella à des fins de contrôle de la transmission parasitaire
Pseudosuccinea columella is one of the main intermediate hosts of Fasciola hepatica, a cosmopolitan snail-borne trematode that affects humans, livestock and wildlife. The occurrence in Cuba of susceptible and naturally-resistant populations of this species to F. hepatica infection (host’s hemocytes encapsulate the parasite upon penetration) offers an interesting Mollusca - Trematoda model with applications on evolutionary biology, health sciences and vector control strategies. Thus, here we explored different ecological, molecular and phenotypical aspects of this system to better understand P. columella resistance. We determined that while susceptible and resistant snails share similar ecological requirements, resistant populations occurred only at low pH (6.5-6.5) and total hardness (TH; 4°-10°d) waters, with low snail species richness, suggesting a high ecological cost of resistance. Comparison of life history traits between susceptible and resistant snails, experimentally-reared at low or common pH/TH conditions, showed that resistant populations display higher tolerance to pH/TH variations and a lower reproductive potential. To gain more insights on the molecular bases of the features associated to resistance in P. columella, we performed comparative “omics” approaches on naïve snails from both phenotypes at whole snail level (RNAseq) and at the albumen gland level (2D-electrophoresis). This thesis presents the latest efforts to broadly characterize this model, which constitute building steps for the comprehension of P. columella resistance and for its application to tackle parasite transmission

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Tavares, Luiz Eduardo Roland. "Composi??o e estrutura das comunidades de metazo?rios parasitos de Aspistor luniscutis e Genidens barbus (Osteichthyes: Ariidae) e Anchoa marinii e A. tricolor (Osteichthyes: Engraulididae) do litoral do estado do Rio de Janeiro, Brasil." Universidade Federal Rural do Rio de Janeiro, 2006. https://tede.ufrrj.br/jspui/handle/tede/821.

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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Between March 2000 and February 2003 63 specimens of sea catfishes G. barbus and 69 specimens of A. luniscutis and Between October 2001 and July 2003, 103 specimens of anchovies A. tricolor and 95 specimens of A. marinii from the coastal zone of the State of Rio de Janeiro (23?01'S, 43?38 - 44?19'W), Brazil, were necropsied to study their communities of metazoan parasites. Additionally, data obtained from 136 specimens of A. marinii and 115 specimens of E. anchoita, from the coastal zone of Mar del Plata (38?08 S, 57?32 W), Argentine, necropsied between November 1993 and February 1999, and were included in the present analysis. Ecological and community parasitic descriptors were calculated and its possible similarities statistically tested. Ergasilus youngi Tavares & Luque, 2005, parasitic on the gills of sea catfish, Aspistor luniscutis from the coastal zone of the state of Rio de Janeiro, Brazil is described and illustrated. Twenty three species of metazoan parasites were determined, 15 species parasitic in G. barbus and 17 parasitic in A. luniscutis, and 25 species of metazoan parasites from engraulidids were determined. Only P. merus was founded in all host species sample, although other four species were common to both Brazilian and Argentinean samples. The parasite infracommunities of A. luniscutis e G. barbus were characterized by ectoparasite dominance and scarcity of core species. The communities of metazoan parasites of the studied anchovies were characterized by dominance of larval endoparasites. Similarity between parasitic communities of sympatric species of ariid could be explained by habitat overlapping and similar biological behavior, that might expose to the same infective forms. Greater similarity observed between samples belonging to the same locality suggests the influence of ecological factors on the parasitic community structure of these species of engraulidids.
Entre mar?o de 2000 e fevereiro de 2003 foram necropsiados 63 esp?cimes de bagres marinhos G. barbus e 69 esp?cimes de A. luniscutis e entre outubro de 2001 e julho de 2004 foram necropsiados 103 esp?cimes de manjubas de A. tricolor e 95 esp?cimes de A. marinii do litoral do estado do Rio de Janeiro (23?01'S, 43?38 - 44?19'W), Brasil, para o estudo de suas comunidades de metazo?rios parasitos. Adicionalmente, foram inclu?dos na an?lise dados obtidos de 136 esp?cimes de A. marinii e 115 esp?cimes de E. anchoita, provenientes do litoral de Mar del Plata (38?08 S, 57?32 W), Argentina, necropsiados entre novembro de 1993 e fevereiro de 1999. Para cada amostra de hospedeiro foram calculados os descritores ecol?gicos e comunit?rios do parasitismo e suas poss?veis similaridades testadas estatisticamente. Ergasilus youngi Tavares & Luque, 2005, parasita das br?nquias do bagre marinho Aspistor luniscutis do litoral do estado do Rio de Janeiro, Brasil, ? descrita e ilustrada. Foram determinadas 23 esp?cies de metazo?rios parasitos de ar?deos, 15 esp?cies parasitando G. barbus e 17 em A. luniscutis, sendo que nove esp?cies foram comuns ?s duas esp?cies de hospedeiros e determinadas 25 esp?cies de metazo?rios parasitos de engraulid?deos, sendo que apenas a esp?cie P. merus foi encontrado nas quatro amostras de hospedeiros, embora outras quatro esp?cies tenham ocorrido em comum entre amostras brasileiras e argentinas. As infracomunidades parasit?rias de A. luniscutis e G. barbus foram caracterizadas pela domin?ncia de ectoparasitos e escassez de esp?cies centrais. As comunidades parasit?rias das manjubas estudadas foram caracterizadas pela domin?ncia de endoparasitos em est?gio larvar. A similaridade entre as comunidades parasit?rias das esp?cies simp?tricas de ar?deos pode ser explicada em fun??o compartilhamento de h?bitat e similaridade de comportamento biol?gico, que podem favorecer a exposi??o ?s mesmas formas infectantes. A maior similaridade observada entre as amostras da mesma localidade sugere a influ?ncia de fatores ecol?gicos sobre a estrutura das comunidades parasit?rias destas esp?cies de engraulid?deos.

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STRONA, GIOVANNI. "Investingating the relationships between fish parasites and their hosts: an ecological approach." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2010. http://hdl.handle.net/10281/10932.

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Fish parasite assemblages from different areas and environments were examined in search for significant patterns related to parasite host specificity. Ecological niche models were used to test the relevance of ecological factors in the qualitative determination of the parasite species assemblages on host species. The host/parasite cospeciation paradigm was discussed, with the proposal of a theoretical framework aimed to integrate the role of coevolutionary and ecological factors in the determination of parasite host range. Host specificity was investigated through different statistical techniques. A new protocol to assess relative nestedness within a species assemblage was developed. Relative nestedness of parasite taxa was then proposed as a measure of their intrinsic host specificity. Trophic ecology of fish hosts resulted to be a key factor in determining the qualitative composition of parasite assemblages. The fundamental ecological and evolutionary role played by contactability (the reciprocal potentiality of a host and a parasite to come in contact) provided new insights on the traditional theoretical paradigm stating that host range of a parasite species results from the intersection between the set of compatibile host species and that of encountered ones.

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Lello, Joanne. "The community ecology of rabbit (Oryctolagus cuniculus) parasites." Thesis, University of Stirling, 2003. http://hdl.handle.net/1893/25418.

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This thesis investigates aspects of the community ecology of rabbit parasites with particular emphasis upon the gut helminths, utilising a 23 (later extended to 26) year time series of rabbits and their parasites. A clearer understanding of parasite communities can lead to more effective biological control strategies. Rabbits are regarded as a serious pest species throughout Europe and the Antipodes and the use of the myxomatosis virus, as a biological control agent, has already been tried and failed. However, a clearer picture of the parasite community may offer future possibilities for control. Additionally, the rabbit is a good model for other grazing species, as it carries a similar gut helminth community. Drug resistance is an increasing problem in a wide range of parasites. A clearer appreciation of parasite communities could also aid in the search for effective and environmentally sound pathogen control strategies (e.g. via cross immunity or competition with benign species). Theoretical models have revealed the importance of aggregation to the stability of the host parasite relationship, to parasite evolution and to interspecific parasite interactions. A number of models have considered the effect of varying aggregation upon these dynamics with differing outcomes to those where aggregation was a fixed parameter. Here the stability of the distribution for each of the rabbit helminths was examined using Taylor's power law. The analyses revealed that aggregation was not a stable parameter but varied with month, year, host sex, host age, and host myxomatosis status. Evidence for the existence of interspecific parasite interactions in natural systems has been equivocal. Factors influencing parasite intensity were evaluated for the gut helminth. A network of potential interactions between the parasites was revealed. Only month was shown to be of greater influence on the community. Following, from the above analyses, a community model was constructed which incorporated both seasonal forcing and interspecific parasite interactions, with interaction mediated via host immunity. One unexpected emergent property was an interaction between the seasonality and the immune decay rate with slower immune decay resulting in a shift of the immune response out of phase with the species against which it was produced. The model was also used to assess the potential effects of two control strategies, an anticestodal and a single species vaccine. The vaccine had greater effects on the whole community than the anticestodal because of the immune- mediated interactions. The host is also an integral part of the community as the parasite dynamics are linked with that of their host. Therefore an assessment of the parasites' impact upon host condition and fecundity was also undertaken. This revealed a variety of positive and negative associations between the parasites and their host, with potential implications for future host control strategies. This study has shown that ignoring parasite-parasite or parasite-host interactions and interactions of both the host and the parasite with the external environment, could result in a poor description of the community dynamics. Such complexities need to be considered and incorporated into theory if future control strategies for either host or parasites are to be effective.

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Tompkins, Daniel Michael. "Evolutionary ecology of bird-parasite associations." Thesis, University of Oxford, 1996. http://ora.ox.ac.uk/objects/uuid:a5f5ea19-b799-490b-b738-99ff52df25c1.

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This thesis investigates the ecological determinants of chewing louse (Insecta: Phthiraptera) host-specificity on four species of Malaysian swiftlets (Aves: Apodidae). Influences of host coloniality on louse ecology were also demonstrated, illustrating the dependence which these permanent ectoparasites have on their hosts. Louse collections were made to look for incidences of host-specific lice occurring on the "wrong" host ("straggling"). Straggling was observed, implying that lice disperse among host species. Thus, opportunity for louse dispersal (or lack thereof) does not govern the host-specificity of chewing lice on swiftlets. Experimental transfers of lice between hosts were conducted. Louse survival was reduced on foreign host species. This implies adaptation to specific host characters, suggesting that specialisation governs chewing louse host-specificity on swiftlets. There was no evidence for reciprocal adaptation of swiftlets to their normal louse species. Lice had no impact on the fitness of either swiftlets or the related common swift. Furthermore, neither swiftlet nor swift lice were transmitting pathogenic endoparasites. This implies that chewing lice and Malaysian swiftlets have not "coevolved". Survival of transferred lice was determined by the relatedness of donor and recipient hosts. Closer related swiftlet species are more similar in body size and feather dimensions. When the feather dimensions of the microhabitat distributions of the same louse species on different hosts were compared the results suggested that lice keep the dimensions of barb and barbule diameter, at which they occur, "constant" through microhabitat shifts. This suggests that feather dimensions are the host characters which determine the survival (and host-specificity) of chewing lice on birds. The ability of chewing lice to survive on hosts with similar feather morphology implies that "host-switching", between distantly related hosts with similar morphological characters (due to parallel or convergent host evolution), may have been an important factor in the evolution of bird-louse associations.

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SIM?ES, Raquel de Oliveira. "Biodiversidade dos helmintos parasitos dos roedores simp?tricos Oligoryzomys nigripes e Akodon spp. (Rodentia: Sigmodontinae), na Mata Atl?ntica." Universidade Federal Rural do Rio de Janeiro, 2009. https://tede.ufrrj.br/jspui/handle/tede/785.

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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The objective of this study was to describe the composition and structure of helminthes community comparing the helminthes community component and infracommunity from sympatric rodents Akodon spp. and Oligoryzomys nigripes in the Atlantic Forest and in the different fragments size and the Parque Nacional da Serra dos ?rg?os (PARNA SO reserve. One hundred and fifty-six specimens of Akodon spp. and fifty-seven of Oligoryzomys nigripes were collected in Teres?polis, being 38 rodents in 4 small fragments (30 Akodon spp. and 8 O. nigripes), 58 in 4 medium fragments (43 Akodon spp. and 15 O. nigripes), 87 in 4 large fragments (67 Akodon spp. and 20 O. nigripes) and 30 in PARNASO (16 Akodon spp. e 14 O. nigripes). The stydy was done for two years (2004- 2005). The animals were necropsied and the viscera and cavities examined to helminthes parasites. A total of eighteen helminthes species were collected: 15 from Akodon spp. and12 from O. nigripes. Nine species were common for both rodents. The rodent Akodon spp. showed a higher richness than O. nigripes. A low degree of similarity between the helminthes infracommunities from Akodon spp. and O. nigripes was detected, although these rodents species live in coexistence. The terrestrial and arboreal behavior of O. nigripes and terrestrial behavior of Akodon spp. would determine this difference between both parasite communities. Probably, with the share of soil resource boths species of rodents could disseminate or be infected by the parasite. The prevalence of Stilestrongylus aculeata and mean abundance for Stilestrongylus eta increased, respectively, in small, medium and large fragments in Akodon spp.. The rodent O. nigripes showed high prevalence rate and mean abundance values for Stilestongylus lanfrediae (over 86%) regardless of the fragments size studied. The difference in mean richness for Akodon spp. and O. nigripes in different fragments size and PARNASO were not significant. There were variations between the helminthes infracommunities for the two species of rodent in different fragments size and PARNASO. These differences may also be related to the environmental changes that can produce both positive and negative effects on the transmission of helminthes parasites.
O objetivo deste trabalho foi descrever a composi??o e estrutura da comunidade helm?ntica comparando a comunidade componente e a infracomunidade dos helmintos das popula??es de roedores simp?tricos Akodon spp. e Oligoryzomys nigripes na Mata Atl?ntica e os diferentes tamanhos de fragmentos e a reserva do Parque Nacional da Serra dos ?rg?os (PARNASO). Cento e cinq?enta e seis esp?cimes de Akodon spp. e cinq?enta e sete de O. nigripes foram coletados no munic?pio de Teres?polis, sendo 38 roedores em 4 fragmentos pequenos (30 Akodon spp. e 8 O. nigripes), 58 em 4 fragmentos m?dios (43 Akodon sp p. e 15 O. nigripes), 87 em 4 fragmentos grandes (67 Akodon spp. e 20 O. nigripes) e 30 no PARNASO (16 Akodon spp. e 14 O. nigripes). O estudo foi feito durante dois anos (2004- 2005). Os animais foram necropsiados tendo suas v?sceras e cavidades tor?cica e abdominal examinadas para recupera??o de helmintos parasitos. Um total de 18 esp?cies de helmintos foram coletados: 15 em Akodon spp. e 12 em O. nigripes. Nove esp?cies foram comuns aos dois roedores. O roedor Akodon spp. teve uma maior riqueza parasit?ria do que O. nigripes. Um baixo grau de similaridade entre as infracomunidades de helmintos de Akodon spp. e O. nigripes foi observado, embora sejam esp?cies que coexistam. O comportamento terrestre e arbor?cola de O. nigripes e apenas terrestre de Akodon spp. poderia determinar essa diferen?a entre as duas comunidades de helmintos parasitos. Provavelmente, ao compartilharem os recursos do solo, ambas as esp?cies podem se infectar ou disseminar o parasita. A preval?ncia para Stilestrongylus aculeata e a abund?ncia m?dia para S. eta aumentaram, respectivamente, nos fragmentos pequenos, m?dios e grandes no Akodon spp.. O roedor O. nigripes apresentou elevada taxa de preval?ncia e valores de abund?ncia m?dia para S. lanfrediae (acima de 86%) independente do tamanho dos fragmentos estudados. A diferen?a na riqueza m?dia de Akodon spp. e O. nigripes nos diferentes tamanhos de fragmentos e no PARNASO n?o foi significativa. Houve varia??es entre as infracomunidades de helmintos das duas esp?cies de roedores nos diferentes tamanhos de fragmentos e PARNASO, podendo essas diferen?as estarem relacionadas com as altera??es ambientais causadas pela fragmenta??o que podem produzir tanto efeitos positivos como negativos na transmiss?o dos helmintos parasitos.

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Leung, Tommy Ling Fong, and n/a. "Interspecific and intraspecific interactions of trematodes parasitising the New Zealand cockle Austrovenus stutchburyi." University of Otago. Department of Zoology, 2008. http://adt.otago.ac.nz./public/adt-NZDU20090105.160127.

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Most organisms are rarely infected with just a single species of parasite and are usually simultaneously infected with a range of species. Thus, the parasite fauna of a host represents an entire community composed of multiple individuals from many different species. In nature, it is within the host that parasites can encounter conspecifics and individuals from other species. As in any ecosystem, while such interactions between parasites can be antagonistic due to competition or conflicting interests, association between different species can also be beneficial. In this thesis, I investigated patterns of associations between parasites in the New Zealand cockle Austrovenus stutchburyi through a combination of descriptive and experimental studies employing both standard ecological field techniques and molecular biology methods. It was found that the presence and infection intensity of various parasites species are not independent of each other. Among cockles, an association was found between two trematode taxa, i.e. between the infection intensity by foot-encysting echinostomes and the metacercariae of Gymnophallus sp. It was also found that the presence of the parasitic copepod Pseudomyicola spinosus was associated with greater infection intensity by the echinostomes but not Gymnophallus sp. While it was postulated that the positive association between the echinostomes and Gymnophallus sp. was due to the latter�s preference to infect cockles that are stranded on the sediment surface as a result of heavy echinostome metacercariae burden in their foot, a field experiment found that Gymnophallus cercariae did not preferentially infect cockles that have been forced to remain above the sediment surface as opposed to those that were forced to remain buried. Meanwhile, the two species of echinostomes known to encyst in the cockle�s foot, Acanthoparyphium sp. and Curtuteria australis, were found to represent cryptic species complexes. The presence of such cryptic species means that it is possible that some potential interspecific interactions are overlooked. A study of the population structure of Gymnophallus sp. found that each cockle contains multiple genetically distinct individuals and that clonal individuals rarely co-occur in the same cockle. This adds to the growing body of evidence suggesting that in addition to acting as a means of reaching the definitive host, the second intermediate host also acts to promote genetic diversity by accumulating cercariae shed by multiple first intermediate hosts in the environment. An experimental infection study conducted with Curtuteria australis cercariae deriving from singly-infected first intermediate hosts revealed that different clonal lineages varied with respect to their contribution to host manipulation. It was found that while certain lineages have a preference for host manipulation, others tend to adopt a "hitch-hiker"-type life history strategy. However, this genetic predisposition was also found to be a phenotypically plastic trait, as the presence of a higher number of manipulators seems to encourage newly-arrived cercariae to become manipulators, regardless of clonal lineage. This thesis provides evidence that patterns of interactions can affect various aspects of parasite life history. Apart from host condition, parasites can also be affected by other parasites. Studying the dynamics of mixed infections can provide informative insights for evolutionary and ecological research.

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30

Gregory, Richard D. "Host-parasite interactions : population and community ecology." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276582.

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31

Castel, Magda. "Ecologie et évolution théoriques des parasites de plantes annuelles." Rennes, Agrocampus Ouest, 2013. http://www.theses.fr/2013NSARC112.

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Les écosystèmes agricoles tempérés sont caractérisés par l'absence périodique de plantes hôtes, qui peut avoir un impact sur l’évolution des parasites. Pour être durable, la protection des cultures doit intégrer le potentiel évolutif des parasites. Cela nécessite une vision épidémiologique à long-terme peu accessible à l’expérimentation, et rend le recours aux modèles épidémiologiques pluriannuels particulièrement pertinent. Nous considérons une famille de modèles dits semi-discrets, correspondant à différents cycles de vie, selon le mode de reproduction du parasite et son mode d'infection primaire. Sous l'hypothèse d'un compromis entre multiplication pendant la saison et survie de saison en saison, une analyse de dynamique adaptative montre qu’une différentiation temporelle de niche écologique peut conduire à la diversification et à la coexistence de parasites aériens. Ces résultats sont cependant obtenus sous l'hypothèse d'une reproduction strictement asexuée, ne correspondant pas à la biologie de tous les parasites de plantes. Certains parasites produisent des formes de survie par reproduction sexuée auto-incompatible. Or, si cette dernière est obligatoire, la nécessité de trouver un partenaire sexuel compatible induit de la densité-dépendance positive à faible densité (effet Allee démographique). Sous l'hypothèse d'un compromis entre multiplication asexuée pendant la saison et allocation des ressources dans des formes de survie sexuées, nous montrons que l'évolution peut notamment conduire à la coexistence d'un morphe à reproduction strictement sexuée, et d'un morphe qui se reproduit par parthénogenèse cyclique. Cela nous permet d'émettre une nouvelle hypothèse expliquant le polymorphisme souvent observé en termes d'investissement dans la reproduction asexuée chez les parasites des plantes
Agricultural ecosystems under seasonality are characterized by periodic host plant absence, which may impact parasite evolution. Sustainable crop protection must incorporate parasite evolution. This requires a long-term epidemiological perspective, which is hardly amenable to experimentation, and makes multi-annual plant epidemic models particularly relevant. We consider a family of such models, termed semi-discrete models, which correspond to distinct life cycles, depending on the parasite reproduction mode (sexual or asexual) and its primary infection mode (airborne or soilborne, i. E. With or without negative density-dependence, respectively). Under the assumption of a trade-off between in-season multiplication and season-to-season survival, an adaptive dynamics approach shows that temporal niche differentiation can lead airborne parasites to diversify and coexist. These results assume a strictly asexual parasite life cycle, which does not correspond to all plant parasites. Some parasites produce survival forms by self-incompatible sexual reproduction. When sexual reproduction is mandatory, the need to find a mate induces positive density dependence at low density (demographic Allee effects). Under the assumption of a trade-off between in-season asexual multiplication and resource allocation to sexual survival forms, we show that evolution may lead to the coexistence of a strictly sexual morph with a cyclic parthenogenetic morph. Our findings provide a novel hypothesis (positive density dependance and Allee effects) for the frequent coexistence of sexual and asexual plant parasites

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32

Gerphagnon, Mélanie. "Ecologie des chytrides parasites de la cyanobactérie Anabaena macrospora." Thesis, Clermont-Ferrand 2, 2013. http://www.theses.fr/2013CLF22385/document.

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En raison des forçages anthropiques exercés sur les écosystèmes aquatiques et des effets des changements globaux présents et à venir, on s’attend à une augmentation de la fréquence et de l’intensité des proliférations cyanobactériennes lacustres. Une meilleure connaissance des facteurs biotiques, et notamment du parasitisme, impliqués dans le control des dynamiques cyanobactériennes semble essentielle. Il est désormais établi que les Chytridiomycota (chytrides) constituent les principaux pathogènes fongiques du phytoplancton. Ainsi, les travaux de recherche menés au cours de cette thèse ont eu pour objectif d’étudier le parasitisme fongique associé aux efflorescences cyanobactériennes, et plus précisément l’écologie des chytrides parasites de la cyanobactérie Anabaena macrospora, espèce filamenteuse présentant des proliférations massives et récurrentes dans le lac d’Aydat (France). Par la mise en place d’un schéma d’échantillonnage temporel et spatial à haute fréquence et prenant en compte deux années consécutives (2010 et 2011), nous avons pu (i) étudier les cycles de vie des deux espèces de parasites fongiques associées à A. macrospora, (ii) évaluer l’impact de ces parasites sur la dynamique de la population cyanobactérienne, et (iii) caractériser des facteurs contrôlant la dynamique des systèmes hôtes-parasites d’intérêt. De plus, (iv) afin de mettre en exergue les relations étroites existantes entre l’hôte et la production fongique associée, nous avons mis au point des protocoles méthodologiques permettant une analyse microscopique fine de l’hôte, des sporanges et de leur contenu en zoospores (fécondité des chytrides). Les résultats acquis mettent en évidence la coexistence de deux espèces de chytrides, Rhizosiphon crassum et R. akinetum, associées à A. macrospora. La reconstruction des cycles de vie par analyse d’images prises à partir d’échantillons naturels nous a permis de montrer que les deux chytrides présentaient une durée de leur cycle de vie similaire, et estimée à environ 3j. pour R. crassum. Cependant, ces deux espèces se différencient d’un point de vue fonctionnel en parasitant des types cellulaires distincts : R. crassum influence directement la biomasse active en parasitant les cellules végétatives, alors que R. akinetum parasite les cellules de résistances (akinètes) de A. macrospora. Cette dernière espèce peut donc avoir un impact sur le recrutement, la structure génétique et la variabilité interannuelle de la population hôte. Par ailleurs, outre leur impact direct, nous montrons que l’action des chytrides parasites peut aboutir à une fragmentation mécanique des filaments de A. macrospora, augmentant potentiellement la perte de biomasse cyanobactérienne par broutage. De plus, nous avons pu mettre en évidence que la production zoosporique des chytrides dépendait des ressources nutritives disponibles tant d’un point vue quantitatif (taille de l’hôte) que qualitatif (groupe phytoplanctonique parasité, métabolisme de l’hôte...). La réduction de la biomasse active de cyanobactéries, la fragmentation mécanique, ainsi que la production de zoospores dont la qualité nutritive pour le zooplancton a été démontrée, établissent les chytrides comme lien trophique entre les proliférations cyanobactériennes filamenteuses « inedible », considérée comme impasses trophiques, et les niveaux trophiques supérieurs. Enfin, l’ensemble des résultats acquis montre l’intérêt de prendre en compte, désormais, le rôle fonctionnel des champignons microscopiques parasites, notamment comme agents régulateurs direct et indirect du développement phytoplanctonique. Cette prise en compte permettrait, sans aucun doute, d’améliorer les modèles de transferts de matière et d’énergie qui transitent dans les écosystèmes aquatiques, dans le contexte général d’optimiser la gestion des plans d’eau
Face to both the important anthropogenic input in nutrients and the global change, numerous authors predict that the cyanobacterial blooms will increase in relative abundance in aquatic ecosystems. An exhaustive knowledge of the driving biotic factors of the cyanobacterial dynamic is essential. In lakes, the most common fungal parasites of phytoplankton belong to the phylum Chytridyomycota (i.e. chytrids). The aim of the thesis was to investigate the fungal parasitism associated to the cyanobacterial blooms, particularly the ecology of chytrids parasitizing the filamentous cyanobacterial species Anabaena macrospora, in Lake Aydat (France). During two successive years (2010-2011), investigations on (i) the chytrid cycle of life of two chytrid species parasitizing A. macrospora, (ii) the impact of the fungal parasitism on the cyanobacterial bloom dynamic and (iii) driving factors of the host-parasite pairings dynamics have been led during two spatio-temporal surveys using high resolution sampling strategies. Moreover (iv) a double staining method based on a combination of CFW and SYTOX green for counting, identifying, and investigating the fecundity of phytoplankton fungal parasites and the putative relationships established between hosts and their fungal parasites has been developed. Results underlined the coexistence of two chytrids, Rhizosiphon crassum and R. akinetum, which have similar life cycles but differed in their infective regimes depending on the cellular niches offered by their host. R. crassum infected both vegetative cells and akinetes while R. akinetum infected only akinetes. A reconstruction of the developmental stages suggested that the life cycle of R.crassum was completed in about 3 days. By infecting akinetes, R. akinetum could reduce or modify the genetic structure of the cyanobacterial bloom of the following year. Furthermore, chytrids may reduce the length of filaments of Anabaena macrospora significantly by ‘‘mechanistic fragmentation’’ following infection. All these results suggest that chytrid parasitism is one of the driving factors involved in the decline of cyanobacterial blooms, by direct mortality of parasitized cells and indirectly by the mechanistic fragmentation, which could weaken the resistance of A. macrospora to grazing. Moreover, we underlined that the production of zoospore depends on the nutritional host quantity (host size) and quality (host phytoplanktonic group, host metabolism...). The decrease of the cyanobacterial active biomass, mechanistic fragmentation, and production of zoospores which exhibit a high nutritional quality for the zooplankton, established the chytrids as a real link between the inedible filamentous cyanobacteria, considered as trophic dead ends, and the higher trophic levels. Overall, we consider that the acquisition of our data places the chytrid parasitism as an important driving factor of the phytoplankton dynamic, allowing the inclusion of fungi and their main function (parasitism) in the energy and matter fluxes in the pelagic ecosystems

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33

Chandler, Mark. "The evolutionary ecology of parasitism in relation to recombination in a neotropical community of anurans." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39826.

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The rate of recombination and parasite load of species of anuran from Peruvian Amazonia were examined to test the idea that recombination functions to diversify progeny in order to resist the continual counter-adaptation of parasites. The anurans were found to be hosts to over 32 species of macroparasite, as well as a wide variety of protistan and moneran parasites. It was found that a combination of three variables (diet, habitat, abundance), together with host body size accounted for a substantial proportion of the variation in mean parasite richness and parasite species distribution among host species. The relationship between parasites and ecology was found to be independent of host phylogeny. The demonstration of substantial environmental heterogeneity in parasitization predicates that a positive relationship between parasite richness and recombination should be found in this case. This prediction was supported by the data: highly parasitized species of anuran had higher rates of recombination. This is the first study to demonstrate a direct positive relationship between recombination (rather than sex) and parasites.

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34

Mahmud, Muayad Ahmed. "Evolutionary ecology of virulence in a fish parasite." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32945/.

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Virulence (parasite- induced host fitness reduction) is thought to correlate positively with pathogen reproduction rates, but its relationship with pathogen transmission is likely to be determined by a trade- off between the costs and benefits of harming hosts. This project aims to investigate factors which affect host-parasite interactions and particularly those which may play a role in virulence evolution. In doing so, it describes experiments carried out using a monogenean ectoparasitic flatworm (Gyrodactylus arcuatus) and its three-spined stickleback (Gasterosteus aculeatus) host. Populations of this fish species experience a range of both environmental and ecological conditions. Such environmental heterogeneity has been found to drive changes in fish phenotypic traits such as morphology, behaviour, life history and physiology which may consequently affect parasite fitness. I demonstrate that under these conditions, parasite strains from different host populations evolve variation in virulence levels. I also reveal that coevolution in this host parasite system is likely to lead to local adaptation of G. arcuatus at the host population level. I show that competition between parasite species sharing a single host leads to increased parasite reproduction rates, but it shortens the infection time which may be due to earlier stimulation of host immune responses. I show that virulence is neither influenced by the population density, immunity (epidermal mucus), social behaviour of fish hosts nor the natural parasite life expectancy. Lastly, I find that virulence in this system is negatively influenced by the density of stickleback predators and positively associated with loch water pH. Taken together, these results suggest that in this host parasite system, both ecological and environmental factors which drive phenotypic changes in fish hosts may evolutionarily feedback to affect parasite virulence.

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35

Lynsdale, Carly L. "Evolutionary ecology of parasite infection in Asian elephants." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/19058/.

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36

AMARANTE, Cristina Fernandes do. "Fatores associados ? agrega??o, ? abund?ncia e ? domin?ncia parasit?ria em peixes coletados no Estado do Rio de Janeiro, Brasil: um enfoque ecoepidemiol?gico." Universidade Federal Rural do Rio de Janeiro, 2016. https://tede.ufrrj.br/jspui/handle/jspui/1325.

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CNPq
This study aimed to assess the factors involved in the determination of ecological events, including parasite aggregation, abundance, and dominance, via multivariate analysis using fish as a biological model. For this purpose, we used a database consisting of 3,746 fish specimens collected on the coast of Rio de Janeiro and from the Guandu river and evaluated their characteristics, habits, and associated parasites. Parasites were grouped into seven higher taxa: Nematoda, Monogenea, Cestoda, Trematoda, Acanthocephala, Hirudinea, and Crustacea. Aggregation was calculated using the dispersion index; abundance was determined by calculating the total number of parasites; and dominance was calculated using the Berger-Parker index. Data normality was tested using the Shapiro-Wilk test; group comparisons, when necessary, were performed using the Wilcoxon test or the Kruskal-Wallis test. Adjustments were made in the linear regression models for parasite aggregation in each parasite taxon evaluated and in the mixed-effect models to evaluate abundance and dominance using Poisson and Gaussian distributions, respectively. The factors inherent to the hosts, including sex, size, habitats, formation of schools, eating habits, and aquatic environments, were tested as potential explanatory variables of these ecological events. In addition, the parasite development stage and parasite taxa were included as explanatory variables in the analysis of the determinants of aggregation and dominance, respectively. In the mixed-effects model, the ecological events were considered an outcome variable, and fish species were considered a random variable. Regression coefficients were calculated in the study of aggregation, and parasite dominance and prevalence rate were estimated in the study of abundance. Significance was determined using confidence intervals (CI) and the Wald test. All calculations were performed using R software with a confidence interval of 95%. Statistically significant associations between levels of parasite aggregation and explanatory variables (factors inherent to the host and the percentage of larvae) varied according to the parasite taxon. The coefficient of determination was lower than 60% in all of the adjusted models, indicating that factors other than those analyzed may be associated with the level of parasite aggregation. Parasite abundance was significantly associated with sex, formation of schools, habitats, and host length, which were considered risk factors. The numerical dominance of parasites was significantly associated with host length and the taxa Nematoda, Trematoda, Monogenea, Hirudinea, and Crustacea. In addition, our results indicate that the mixed-effects model was more parsimonious compared with the classical model, underscoring the importance of choosing a statistical model that takes into consideration the nature of the data to avoid spurious results, especially when autocorrelations data were not considered. In general, our results point to the need for developing studies with more comprehensive databases and larger samples of parasite species, in which data on the life cycles of fish species and parasite taxa can be analyzed more thoroughly.
Este trabalho teve como objetivo avaliar fatores envolvidos na determina??o dos eventos ecol?gicos: agrega??o, a abund?ncia e a domin?ncia parasit?ria por meio de an?lises multivariadas, utilizando peixes como modelo biol?gico. Para tanto, foi utilizado um banco de dados composto por 3.746 esp?cimes de peixes, suas caracter?sticas e h?bitos e seus parasitos, provenientes do litoral do Rio de Janeiro e do Rio Guandu. Os parasitos foram agrupados em sete t?xons superiores: Nematoda, Monogenea, Cestoda, Trematoda, Acanthocephala, Hirud?nea e Crust?cea. A agrega??o foi calculada atrav?s do ?ndice de dispers?o; a abund?ncia pela quantidade total de parasitas computados; e a domin?ncia atrav?s do ?ndice de Berger Parker. A normalidade dos dados foi testada pelo teste de Shapiro Wilk e a compara??o de grupos, quando necess?ria, foi realizada pelo teste de Wilcoxon ou Kruskal-Wallis. Foram ajustados modelos de regress?o linear para a agrega??o parasit?ria para cada t?xon parasit?rio estudado e modelos de efeitos mistos para an?lise dos determinantes da abund?ncia e da domin?ncia, com distribui??o de Poisson e gaussiana, respectivamente. Os fatores inerentes aos hospedeiros tais como: sexo, tamanho, habitat, forma??o de cardumes, h?bitos alimentares e ambiente aqu?tico foram testados como poss?veis vari?veis explicativas desses eventos ecol?gicos. Al?m desses, na an?lise dos determinantes da agrega??o e domin?ncia foram inclu?dos os fatores est?dio de desenvolvimento do parasita e os t?xons parasit?rios como vari?veis explicativas, respectivamente. Os eventos ecol?gicos foram considerados vari?veis desfecho e nos modelos mistos a esp?cie de peixe como vari?vel aleat?ria. Foram calculados os coeficientes de regress?o nos estudos de agrega??o e domin?ncia parasit?ria e estimada a raz?o de preval?ncia no estudo de abund?ncia. A signific?ncia foi verificada por meio o intervalo de confian?a (IC) e do teste de Wald. Todos os c?lculos foram realizados utilizando o software R, com um IC de 95%. As associa??es estatisticamente significativas entre o n?vel de agrega??o parasit?ria e as vari?veis explicativas (fatores inerentes ao hospedeiro e propor??o de larvas) variaram conforme o t?xon parasit?rio. O coeficiente de determina??o foi inferior a 60%, em todos os modelos ajustados, indicando que outros, fatores al?m dos analisados, devam estar relacionados ao grau de agrega??o parasit?ria. A abund?ncia parasit?ria mostrou-se associada significativamente ?s vari?veis: sexo, forma??o de cardumes, habitat e comprimento do hospedeiro, que se comportaram como poss?veis fatores de risco. A domin?ncia num?rica de parasitos esteve associada significativamente ao comprimento do hospedeiro e aos t?xons Nematoda, Trematoda, Monogenea, Hirud?nea e Crust?cea. Os resultados mostraram que os modelos mistos foram mais parcimoniosos em rela??o aos modelos cl?ssicos, refor?ando a import?ncia da escolha de um modelo estat?stico mais adequado ? natureza dos dados, evitando-se resultados esp?rios, principalmente quando n?o se leva em conta a autocorrela??o dos dados..De um modo geral, os resultados deste estudo sinalizam para a necessidade de pesquisas com bancos de dados mais abrangentes e com amostras maiores de esp?cies de parasitos, nos quais as caracter?sticas do ciclo biol?gico das esp?cies de peixes e dos t?xons parasit?rios possam ser mais detalhados nas an?lises.

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37

Jackson, M. H. "The epidemiology and ecology of toxoplasmosis." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381379.

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38

Keeling, Matthew James. "The ecology and evolution of spatial host-parasite systems." Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/30/.

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All ecological and epidemiological systems are embedded in space and composed of individuals; these facts often have a profound effect on the dynamics and means many tools and definitions require reformulation. Modelling has always been about taking highly complex dynamical systems, such as the natural environment, and attempting to simplify them to a leve that can be conceptualised, in the process losing all the features that are not understood or not anticipated. The individual based spatial models which form the basis of this work start from the simple rules for individuals and build up to a complex system, allowing new, unexpected phenomenon to arise naturally. The local interactions in spatial models lead to short scale correlations and self-induced spatial heterogeneity as the small fluctuations of environmental noise are amplified into macro-scale patterns. These spatial patterns can lead to ephemeral refuges for hosts from where they can disperse stabilising the dynamics. After discussing the importance and variety of host-parasite interactions several techniques to be used in this work are developed and explained on simple examples. Chapters III and IV introduce a caricature host-pathogen model and how how this deviates from the standard mean field theory approximations. Attention is then turned to host-parasitoid systems and the spatially extended Nicholson-Bailey equations; probems with this coupled map lattice are highlighted and an alternative artificial ecology is formulated. Remaining with the Nicholson-Bailey equations these are forced to be integer based by utilising stochastic events, this greatly stabilises the dynamics hence the method was applied to the persistence of measles epidemics in small populations (=500000). Chapter VII demonstrates how the inclusion of space enhances the effects of parasitism in increasing the evolutionary advantage of sexual hosts over asexual ones. Finally general techniques are developed to implicitly model the effects of spatial correlations and stochastic individual based interactions.

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39

Cumming, Graeme. "The evolutionary ecology of African ticks." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301894.

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40

Finidori-Logli, Valérie. "Ecologie chimique de Diglyphus isaea Walker (Hyménoptera Eulophidae)." Aix-Marseille 1, 1994. http://www.theses.fr/1994AIX11009.

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Diglyphus isaea walker est un hymenoptere entomophage utilise en lutte biologique contre liriomyza trifolii burgess. Nous avons etudie les mediateurs chimiques qui interviennent a differents niveaux du cycle du parasitoide et nous avons souleve les questions suivantes: quelle est la strategie d'accouplement du diglyphus? des signaux chimiques interviennent-ils dans la recherche de l'hote? peut-on modifier le comportement de recherche de l'hote grace a un apprentissage? en etudiant le comportement sexuel du parasitoide, nous avons montre que la reconnaissance de la femelle par le male repose sur des signaux chimiques intervenant a courte distance. Un bouquet pheromonal sexuel de contact a ete mis en evidence. Par ailleurs, nous avons etudie le comportement de recherche du diglyphus en olfactometrie. Les observations demontrent que celui-ci localise les larves du diptere grace a l'emission de signaux volatils provenant du complexe plante-hote. L'agression du vegetal induit la liberation en quantite plus importante de composes qui guideraient le parasitoide jusqu'a son hote, agissant ainsi comme des synomones. Le parasitoide presente une preference accrue pour l'odeur du vegetal sur lequel il a ete eleve. Cette affinite est renforcee par une experience de ponte. Conditionnees a une autre odeur vegetale, les femelles modifient leur comportement

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Carter, Lucy Mary. "Evolutionary ecology of reproductive strategies in malaria parasites." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9910.

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For vector-borne parasites such as malaria, how within- and between-host processes interact to shape transmission is poorly understood. In the host, malaria parasites replicate asexually but for transmission via mosquitoes to occur, specialized sexual stages (gametocytes) must be produced. Once inside the mosquito vector, gametocytes immediately differentiate into male and female gametes, and motile male gametes must swim through the hostile environment of the bloodmeal to find and fertilise female gametes. Despite the central role that gametocytes play in disease transmission, explanations of why parasites adjust gametocyte production in response to in-host factors remain controversial. Furthermore, surprisingly little is known about the mating behaviour of malaria parasites once inside the mosquito. Developing drugs and/or vaccines that prevent transmission by disrupting sexual stages are major goals of biomedicine, but understanding variation in gametocyte investment and male gamete behaviour is key to the success of any intervention. First, I propose that the evolutionary theory developed to explain variation in reproductive effort in multicellular organisms provides a framework to understand gametocyte investment strategies in malaria parasites. I then demonstrate that parasites appear to change their reproductive strategies in response to environmental cues and in a manner consistent with our predictions. Next, I show how digital holographic microscopy can be used to characterise the morphology and motility of male gametes. I then provide evidence for non-random movement of male gametes and that gamete interactions with red blood cells appear to hinder mating success in a bloodmeal. Finally, I discuss the variation in gametocyte differentiation and fertilisation success when exposed to a number of factors implicated in gametocyte activation. The data presented here provides important information on the basic biology of malaria parasite reproductive stages and demonstrates considerable variation in parasite traits and behaviours in response environmental changes; both in the host and in the mosquito vector.

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42

Lo, Cédrik. "Ecologie des parasites de poissons récifaux de l'île de Moorea (Polynésie française)." Pacifique, 1998. http://www.theses.fr/1998PACI0026.

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43

Aguirre, Macedo Maria Leopoldina. "Study on helminth and other parasite communities of oysters." Thesis, University of Exeter, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337758.

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44

Pollitt, Laura C. "Evolutionary ecology of transmission strategies in protozoan parasites." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5771.

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In recent years there has been growing interest in applying frameworks from evolutionary ecology to understand infectious disease. It is becoming increasingly apparent that the interactions between parasites within the host environment can shape parasite phenotypes underlying infection dynamics and transmission. However, the spread of the disease will crucially depend on both within-host and between-host dynamics. Bridging these scales is challenging and for vector borne parasites, such as malaria and trypanosomes, will involve gaining a much better understanding of infection dynamics both within the host and vector. I apply evolutionary ecology frameworks including social evolution, life history theory, and phenotypic plasticity to investigate how parasite phenotypes are shaped by within-host and within-vector environments and examine the implications for inhost survival and between-host transmission. Specifically, I demonstrate that; 1. Within the host; i. In accordance with theory malaria parasites detect and respond to the presence of competitors by altering reproductive strategies to maximise in-host survival. Furthermore, these strategies are fine tuned in response to variation in the within-host environment, including the availability of resources. ii. The reproductive investment strategies of malaria parasites can be applied to explain the transmission strategies of African trypanosomes. This shows how general evolutionary frameworks can be applied to a novel parasite species and demonstrates the explanatory power of an evolutionary approach. iii. The complexity of the within-host environment poses specific statistical challenges for examining the temporal dynamics of parasite life history traits that are often not adequately dealt with, potentially leading to type 1 errors. Methods to evaluate levels of autocorrelation and how to deal with it are applied to datasets of within-infection dynamics. 2. Within the vector; i. Malaria parasites undergo programmed, apoptotic cell death. The occurrence of, and putative explanation for, apoptosis in protozoan parasites is controversial. I demonstrate the importance of quantitative methods and parasite ecology in testing the evolutionary explanations for parasite apoptosis. ii. The links between within-host dynamics and within-vector dynamics are complex and can lead to counter-intuitive implications for the success of between-host transmission. Density-dependent processes result in diverse fitness costs to parasites of crowding. More broadly, these processes could explain why parasites undergo apoptosis. In general my results demonstrate, across vertebrate hosts and insect vectors, how the interactions between parasites and with their environment shapes traits important for the transmission of infectious disease.

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45

Stenger, Brianna Leigh Schneck. "Ecology of Cryptosporidium Parasites in Wild Rodent Populations." Diss., North Dakota State University, 2015. https://hdl.handle.net/10365/27278.

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Cryptosporidium is a genus of ubiquitous parasites that have been detected worldwide in nearly 500 species of amphibians, birds, fish, mammals, and reptiles. Most research has focused on the Cryptosporidium species and genotypes infecting humans and livestock, because of the public health significance and economic importance of the diarrheal disease cryptosporidiosis. Relatively little is known about Cryptosporidium-host dynamics in wildlife hosts, even though a wide range of wildlife species are susceptible to Cryptosporidium. Insights into ecology and host-parasite dynamics in wild populations are necessary to understand the biology and evolution of Cryptosporidium; to predict the emergence of human and livestock pathogens; and to clarify Cryptosporidium taxonomy and systematics. The focus of this research was to study the ecology of Cryptosporidium in populations of cricetid (voles, Peromyscus mice, muskrats) and sciurid (squirrels and chipmunks) rodents, and characterize Cryptosporidium taxa by sequencing multiple genetic loci (18S rRNA and actin genes). Paralogous copies of the 18S rRNA gene in Cryptosporidium genotypes from wild rodents were common and affected phylogenetic inferences. Eastern chipmunks (Tamias striatus) were infected with Cryptosporidium chipmunk genotype II, which had 18S rRNA gene paralogs that shared ~93% similarity. The degree of divergence has not been previously described in any Cryptosporidium taxa, but is similar to the divergence described in Plasmodium species, which have functionally distinct 18S rRNA gene copies. Marmotini squirrels were mainly host to novel Cryptosporidium genotypes, and to the best of our knowledge, we provide the first molecular characterization of Cryptosporidium in black-tailed prairie dogs (Cynomys ludovicianus). Cryptosporidium host adaptation and specificity was not evident in in Sciurini rodents and they were host to two zoonotic taxa, C. ubiquitum and Cryptosporidium skunk genotype. In conclusion, Cryptosporidium was prevalent in cricetid and sciurid rodents, and the extent of host adaptation varied among Cryptosporidium taxa as they are likely shaped by differences in host-parasite ecology and evolution. The rodents sampled are not significant reservoirs of zoonotic Cryptosporidium, with the exception of tree squirrels. Sequencing multiple genetic loci helped identify the presence of paralogs and resolve cryptic Cryptosporidium taxa, which strengthened phylogenetic inferences leading to a better understanding of Cryptosporidium systematics.
USDA (project number: 2008-35102-19260)
NIH (project numbers: 2P20 RR015566, 1R15A1067284-01A1)

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Roux, Olivier. "Système de reconnaissance hôte-parasitoïde et différenciation de populations au sein de l'interaction spécifique Plutella xylostella (Lepidoptera, Plutellidae) et Cotesia plutellae (Hymenoptera, braconidae)." Toulouse 3, 2006. http://www.theses.fr/2006TOU30100.

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La culture de Brassicacées est une des productions agricoles les plus importantes au monde. L'un de ses principaux ravageurs est la Teigne des crucifères, Plutella xylostella (Linné, 1758) (Lepidoptera, Plutellidae) dont les chenilles attaquent les feuilles et peuvent causer jusqu'à 90% de perte de production. La lutte contre la teigne est rendue difficile par le développement de résistances envers la quasi-totalité des insecticides existants. Afin de répondre en partie à ce problème, de nombreux moyens de lutte alternatifs ont été mis en place, impliquant principalement des insectes parasitoïdes. Parmi eux, Cotesia plutellae (Kurdjumov, 1912) (Hymenoptera, Braconidae) est l'un des plus employés mais son introduction dans certaines régions du monde n'est pas toujours efficace. Les hypothèses le plus souvent avancées mettent en cause des phénomènes de compétition, d'adaptation déficiente du parasitoïde à son nouvel environnement ou encore l'usage simultané d'insecticides, mais les capacités du parasitoïde à reconnaître son hôte n'ont jamais été remises en cause. C'est autour de ce dernier point qu'est axée la problématique de notre travail. Dans un premier temps, à partir d'analyses comportementales, d'analyses chimiques et d'une étude en microscopie électronique à balayage, nous avons pu mettre en évidence trois points importants du système de reconnaissance du parasitoïde envers son hôte. (i) Les femelles de C. Plutellae détectent et reconnaissent leur hôte à partir de leur signature chimique, composée par les lipides cuticulaires. (ii) Le stimulus chimique constituant le signal de reconnaissance est composé de plusieurs molécules appartenant à deux classes de lipides et agissant en synergie. (iii) Ce stimulus est perçu par des sensilles gustatives principalement implantées sur les faces dorsales et latérales des antennes des femelles du parasitoïde. Dans un second temps, l'étude de la variabilité de cette signature chimique entre différentes populations d'hôtes nous a permis de mettre en évidence de très fortes disparités pouvant être à l'origine des différences de parasitisme observées suite à des lâchers de parasitoïdes. .
Brassicaceae crops make up a key vegetable production on a world scale. One of its most destructive pests is the diamondback moth (DBM), Plutella xylostella (Linnaeus, 1758) (Lepidoptera, Plutellidae), whose caterpillars attack leaves and can cause almost 90% crop loss. Resistance toward many insecticides leads to more difficulties for DBM management. Among the numerous alternative control techniques, parasitoids are the most used, Cotesia plutellae (Kurdjumov, 1912) (Hymenoptera, Braconidae) being a prime example. However, numerous attempts to introduce it into various areas of the world have often yielded mediocre results. Explanations of these results often involve notions of competition, maladaptation to the new environment and the use of non-selective insecticides. However, the host recognition capacities of the parasitoid have been never questioned. This was the object of the present study. .

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Berry, Katharine M. "The role of parasites in the invasion ecology of Harmonia axyridis." Thesis, University of Stirling, 2017. http://hdl.handle.net/1893/27336.

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The success of an invasive alien species is often attributed to the ecological advantage gained from natural enemy release. Numerous factors have been suggested as contributing to the success of Harmonia axyridis as an invasive alien species, including enemy release. This thesis studied the interactions of several parasites with H. axyridis, investigating parasite transmission, growth and virulence as well as host immune responses, thereby shedding light on the potential role of enemy release in the invasion biology of this ladybird. Benefits gained by invasive alien species from enemy release diminish if parasites of native species shift hosts to exploit the novel invader. The fungal ectoparasite Hesperomyces virescens began infecting H. axyridis shortly after it invaded the UK, probably as a result of a host shift from Adalia bipunctata. This study found a rapid increase in H. virescens prevalence over three years in London H. axyridis populations. Laboratory study showed H. virescens transmission and growth to be more efficient on A. bipunctata than the novel host. In addition, reciprocal interspecific transfers of H. virescens strains isolated from A. bipunctata and H. axyridis revealed that the infection characteristics of the fungi from these two hosts differed, suggesting strains may have diverged after the initial shift from A. bipunctata to better exploit the host from which they were derived. Laboulbenialian fungi were previously thought to have negligible impacts on host fitness. A detailed examination of H. virescens infecting H. axyridis found distinct virulence, with infections resulting in a 50% reduction in host lifespan. In addition, chronic H. virescens infection in males caused acceleration in the age-associated decline in body condition while for females, infection triggered fecundity senescence and a faster age-related decline in fertility. While their role in accelerating ageing is debated, the results presented here provide evidence that infectious diseases can drive the ageing process in this insect species. In nature, multiple parasites affecting a single host are common. The effect of co-infection on the virulence caused by two fungal infections was characterised using H. axyridis and A. bipunctata hosts. The ability of two ladybird species to defend against an acute fungal parasite, while infected with the relatively avirulent H. virescens was found to be sex-specific. While for females, the presence of co-infection did not alter the virulence seen in singly infected females, a higher mortality rate existed for co-infected males compared with those infected singly. Previously, H. virescens has been considered to be avirulent, however, this study provides evidence that this chronic fungal parasite may be important when considering the mortality associated with co-infections in the field. The invasive success of H. axyridis has, in part, been attributed to a more vigorous immune ability compared with other competitor species. Previously, field studies have shown that the prevalence of the parasitoid wasp Dinocampus coccinellae in H. axyridis is considerably lower than in the UK primary host of this wasp, Coccinella septempunctata. The extent to which the prevalence asymmetry in the field is driven by differences in host encapsulation response was tested by first comparing the encapsulation ability of C. septempunctata and H. axyridis directed against an artificial implant. Following this, the encapsulation response of D. coccinellae parasitized individuals was assessed and compared between the two host species. While encapsulation ability did not differ between the host species, and D. coccinellae did not affect the immune response of H. axyridis, wasp parasitism did alter the encapsulation ability of C. septempunctata, although it was inconsistent across sexes and populations. Overall, this thesis furthers our understanding of the fungal parasite H. virescens and its association with the notorious invader H. axyridis. The research presented here also demonstrates the use of H. axyridis as a model system in areas other than invasion ecology and furthermore, contributes to understanding the role of infectious disease in the rate of ageing. Finally, sex-specific effects were found across the chapters of this thesis, demonstrating the use of H. axyridis in the study of sex-specific effects of infections.

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48

Arnal, Céline. "Ecologie comportementale de la symbiose poisson nettoyeur/poisson client : motivations et honnêteté." Perpignan, 2000. http://www.theses.fr/2000PERP0379.

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La symbiose de nettoyage implique un poisson "nettoyeur" qui nettoie le corps de poissons "clients". Cette relation a lieu dans le territoire du poisson nettoyeur : la station de nettoyage. Les nettoyeurs intègrent, lors de leur inspection, des ectoparasites, des écailles et du mucus. Malgré le nombre croissant d'études sur la symbiose de nettoyage, le gain énergétique net issu de cette relation pour les deux protagonistes reste encore à déterminer. Il apparaît ainsi difficile de définir précisement la véritable nature de la relation. Dans ce travail, deux questions principales ont été posées : 1)quels facteurs influencent la symbiose de nettoyage?, et 2) les nettoyeurs sont-ils honnêtes? Quatre espèces de nettoyeurs, issus de trois localités différentes, ont été étudiés : Symphodus melanocercus (Banyuls-sur- Mer), Labroides dimidiatus (Lizard Isaland et Moorea), et les gobies Elacatinus evelynae et Elacatinus prochilos (La Barbade). Une approche de terrain a été utilisée, avec des observations comportementales, des mesures de l'alimentation des nettoyeurs, du parasitisme et des caractéristiques du mucus de leurs clients. Suite à l'étude de chacune des espèces, une comparaison inter-spécifique a été effectuée. L'honnêteté apparaît comme une stratégie importante dans la relation de nettoyage. Ce sont les clients les plus parasités qui visitent le plus les stations de leurs clients. L'honnêteté des nettoyeurs peut, cependant, varier en fonction de plusieurs facteurs comme : l'abondance en ectoparasites, la sexualité, et la localisation de la station de nettoyage. Enfin, il apparaît que chaque espèce de nettoyeur est caractérisée par une spécialisation trophique déterminée, et que les nettoyeurs tropicaux sont plus spécialistes que les nettoyeurs de régions tempérées
Cleaning symbiosis involves a cleaner fish, which cleams the body surface of client fishes. The relationship generally occurs in the cleaner territory : the cleaning station, Cleaner fishes remove ectoparasites, scales and mucus when inspecting their client fishes. Despite years of studies, the net fitness of the two protagonists are still not fully understood. It is, thus, difficult to define clearly this relationship. In this study, two main questions have been asked : 1)what factors influence cleaning interactions? and 2) is the cleaner fish behaviour honest? Four species of cleaner fishes from three localities were studied : Symphodus melanocercus (Banyuls-sur- Mer), Labroides dimidiatus (Lizard Isaland et Moorea), and the gobies Elacatinus evelynae and Elacatinus prochilos (Barbados). Field work experiments were conducted through behavioural observations, and direct measurement of cleaners' diet, clients' ectoparasitim and mucus characteristics. Each species was studied separately, and a comparative analysis was performed. Honesty appears to be an important strategy in cleaning symbioses. The most parasited clients visit cleaning stations higher rates, and ectoparasites are the major items removed by cleaner fishes. Cleaner fish honesty shows variations, depending on ectoparasites density, sex, and the localisation of the cleaning station. Finally, cleaning specialisation appears to be species-specific, which more specialised cleaners in tropical than in temperate waters

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Wright, M. Elizabeth. "Life history ecology of the cestode Diphyllobothrium dendriticum in copepod and fish hosts." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36854.

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Arctic charr are susceptible to cestodes like Diphyllobothrium dendriticum which are transmitted through the food web. Field studies investigating Arctic charr-Diphyllobothrium relationships often provide little data from which to fully understand Diphyllobothrium transmission or to assess their impact on copepod or fish hosts. Experimental studies may, therefore, be the only direct way to investigate these issues. The research goal of this thesis was to duplicate the D. dendriticum life cycle in the laboratory to investigate parasite development and host specificity, and to apply the experimental data to natural situations. Results indicated that at 10°C, D. dendriticum eggs develop slowly and 65 days are required for complete embryonation. In many Canadian Arctic lakes water temperatures rarely exceed 4°C, and this study has shown that at this temperature embryonation requires several months, necessitating more than one ice-free season for life cycle completion. The results also showed that embryos developed more rapidly and significantly more eggs hatched when incubated with light or aeration, results that were consistent for D. dendriticum originating from Canada and Norway. To continue the life cycle, coracidia must be consumed by suitable copepod hosts. This study showed that although D. dendriticum will infect the European copepods Cyclops scutifer and Eudiaptomus graciloides, prevalence was higher and procercoids developed more rapidly in E. graciloides. These results showed that E. graciloides is a better host for D. dendriticum than is C. scutifer, contradicting published literature. In North America, E. graciloides is not found in lakes containing D. dendriticum and no North American calanoid species have been tested to determine their host suitability to this cestode. This study identified two North American species, Diaptomus minutus and D. leptopus, which are suitable laboratory hosts. D. minutus is almost certainly a natural host for D. den

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Tseng, Michelle. "Virulence ecology and evolution in a mosquito and its protozoan parasite." [Bloomington, Ind.] : Indiana University, 2005. http://wwwlib.umi.com/dissertations/fullcit/3204298.

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Thesis (Ph.D.)--Indiana University, Dept. of Biology, 2005.
Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0059. Adviser: Curtis Lively. "Title from dissertation home page (viewed Feb. 21, 2007)."

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Dissertations / Theses on the topic 'Ecologie parasite'

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