Rozprawy doktorskie na temat „Ecologie en résistance”
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Goindin, Daniella. "Étude des résisatances aux insecticides et des réponses biologiques aux changements climatiques du moustique Aedes aegypti, vecteur de la Denguen du Chikungunya et du Zika en Guadeloupe". Thesis, Antilles, 2016. http://www.theses.fr/2016ANTI0054/document.
Pełny tekst źródłaGuadeloupe is an endemic country for Dengue with epidemics every 2 to 3 years. In the past 3 years, other arboviruses have reached the Americas with Chikungunya virus in 2013 and Zika virus in 2015, causing major epidemics including in Guadeloupe. The only known vector of these diseases in Guadeloupe is the mosquito Aedes aegypti. As there is no vaccine nor specific treatment against these infections, prevention against these diseases is achieved through the monitoring and control of mosquito populations. Monitoring methods are based mostly on larval indices, with sometimes controversial results. In addition, vector control methods are based since a very long time on the massive use of chemical insecticides, causing mosquito resistance to these products. This work has therefore focused on two main areas to improve the prevention and control of these arboviruses: i) the search of a new vector population monitoring tool, based on the physiology of adult females and ii) the assessment of the resistance levels and mechanisms regarding three chemical insecticides, Temephos, Malathion (used in the past) and Deltamethrin (currently used). A vector population monitoring model based on females life expectancy as a function of parity rates and according to temperatures has being developed, and tracks on the entomological situations most at risk have emerged. Insecticide resistance tests performed on mosquito larvae have generally found strong Temephos resistance levels and low resistance to Malathion. Adulticide tests showed a moderate resistance of females to Deltamethrin. Molecular investigations have shown very high allelic frequencies for kdr mutations V1016I and F1534C, known to be associated with pyrethroid resistance. Moreover, the evaluation of constitutive expression levels of some detoxification genes revealed significant overexpression in tested Aedes aegypti populations compared to the susceptible Bora-Bora strain, for the carboxy-choline-esterase CCEAE3A, four cytochrome P450 mono-oxygenases (014614, CYP6M11, CYP6BB2 and CYP9J23) and the glutathione-S-transferase GSTE2
Pupier, Chloé A. "Ecologie nutritionnelle des octocoralliaires de Mer Rouge". Electronic Thesis or Diss., Sorbonne université, 2020. http://www.theses.fr/2020SORUS036.
Pełny tekst źródłaOctocorals living in symbiosis with photosynthetic dinoflagellates are one of the major benthic groups of tropical coral reefs. They are notably abundant within disturbed ecosystems where environmental changes have led to the decline of reef-building corals. Although nutrition plays a fundamental role in regulating the abundance of a population, the acquisition of nutrients by octocorals has received little attention to date. The aims of this thesis were to characterize the acquisition and assimilation of autotrophic and heterotrophic nutrients by octocoral species from the Red Sea, from the shallow down to the upper mesophotic zone. The results show that the autotrophic carbon fixation in octocorals is lower at shallow depth compared to scleractinians, but equivalent at mesophotic depths. In addition, the assimilation of dissolved nitrogen compounds is lower in octocorals than in scleractinian corals. These results suggest that octocorals strongly depend on heterotrophic food sources to meet their nutritional requirements. Such mixotrophy provides octocorals with a wide trophic plasticity, which may contribute to their higher resistance to cope with already on-going environmental changes
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.
Pełny tekst źródłaUnderstanding 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
Opatowski-Mezrahi, Lulla. "Modélisation mathématique de la dynamique de diffusion de bactéries résistantes aux antibiotiques : application au pneumocoque". Paris 6, 2009. https://tel.archives-ouvertes.fr/tel-00814070.
Pełny tekst źródłaThe thesis aims at building mathematical models to study the dynamics of pneumococcal strains transmission in the community. The phenomenon of emergence and diffusion of resistant bacteria in populations involve microbial, individual and population scales simultaneously. That makes them complex and difficult to anticipate. In that context, modelling, which allows formalisation and simulation of the different scales, can help in analysing, predicting and understanding better the spread of bacteria. Three main issues are raised. What would be the impact of antibiotic exposure changes on resistances distributions? What would be the effects induced by the pneumococcal conjugate vaccine on the distribution of strains? Do viral respiratory infections and antibiotic consumption play a role in pneumococcal meningitis infections? Four compartmental models are developed to answer these questions. The results of our simulations reinforce the idea that antibiotic exposure is a major factor in the selection of antibiotic resistant bacteria. More precisely, they show that the choices of prescribed drugs and doses at the individual level could have a strong impact on the distributions of resistances in the community. Moreover, our results suggest that respiratory viruses, antibiotic consumption and resistance associated-fitness could explain part of the dynamics of pneumococcal meningitis in the community
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.
Pełny tekst źródłaAzzimonti, Gustavo. "Diversification de la résistance quantitative à la rouille brune du blé, à partir de la caractérisation des composantes de la résistance". Phd thesis, AgroParisTech, 2012. http://pastel.archives-ouvertes.fr/pastel-00803279.
Pełny tekst źródłaAlba, 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.
Pełny tekst źródłaPseudosuccinea 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
Jubert, Isabelle. "Suivi de l'écologie et des résistances bactériennes au CHD Felix-Guyon à l'ile de la Réunion (étude comparative 1997/1998)". Bordeaux 2, 2000. http://www.theses.fr/2000BOR2M032.
Pełny tekst źródłaBenavides, Julio. "Dynamique des maladies dans les systèmes sociaux complexes : émergence des maladies infectieuses chez les primates". Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20163/document.
Pełny tekst źródłaUnderstanding the emergence and spread of infectious disease in wild animal populations has become an important priority for both public health and animal conservation. Combining the collection of empirical data with the development of epidemiological models, this thesis focuses on understanding two key issues of wildlife epidemiology: (i) how heterogeneity at the individual, group, population and landscape level affects parasite spread (ii) investigating whether transmission of antibiotic resistant bacteria from humans to wildlife is occurring within three protected areas of Africa (Tsaobis NP-Namibia, Lope NP-Gabon and Dzanga-Ndoki NP-Central African Republic). The main findings of this work indicated that: (1) multiple-scale factors including temperature, rainfall, home range use, sex, age and body condition influence gastro-intestinal parasite richness among wild baboons; (2) animal contacts around ‘habitat hotspots' can substantially influence the spatio-temporal dynamics of a disease; (3) antibiotic resistant enterobacteria seem to be spreading from humans/livestock to wildlife when the territory overlap between these two populations is expected to be high; (4) gradients in gorilla density created by bushmeat hunting can reverse the expected pattern of decreasing parasite prevalence with distance to human-spillover. The conclusions of this work open new possibilities for studying the mechanisms explaining the spread of emerging infectious diseases among wild animals
Carbillet, Malherbe Jeffrey. "Influence des caractéristiques environnementales et individuelles sur le niveau de stress basal, et conséquences, chez un grand mammifère, le chevreuil Capreolus capreolus". Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30284.
Pełny tekst źródłaOver the last century, extreme climatic events and landscape modifications due to anthropogenic activities have dramatically increased. These rapid and unpredictable changes in the environment are new selective pressures for wild animals, and can threaten their survival and affect population dynamics. Understanding how wild animals cope with these perturbations and their consequences on life history traits and population dynamics is a necessary step to evaluate their evolutionary potential in a changing world. An important mechanism for adaptation to environmental changes is the stress response, which consist of a suite of physiological and behavioural responses that aim to maximise immediate survival. One of the main physiological pathways of the stress response is the hypothalamic-pituitary-adrenal axis, which triggers the secretion of glucocorticoid hormones. Because these hormones drive the mobilisation and distribution of energy, they underlie trade-offs between key functions such as immunity and reproduction. However, not all individuals respond in the same way to stressful situations, resulting in large among-individual differences. In addition, the natural environment not only offers a great deal of variability in stressors, but also means of responding to stress (e.g. the presence of shelters). In turn, the diversity of stress patterns depends on a complex combination of environmental variables and individual factors. The general aim of my thesis was to understand the determinants of the great among-individual differences in baseline stress levels, and to identify some consequences in a long-lived mammal, the European roe deer. The study analysed several measures of stress and their links with environmental and individual characteristics, and combined observation in three wild population and experimentation in captive roe deer. Using an integrative approach, I found that proxies of stress level (N:L ratio and faecal cortisol metabolites [FCMs]) were moderately repeatable and weakly associated with behavioural response to capture. In two populations, stress levels were higher during years of poor resources quality. I also found that FCMs of roe deer increased with proximity to human infrastructures, but this effect was buffered by behavioural adjustments such as using forest as refuge and adopting nocturnal activity patterns. Secondly, I showed that environmental and behavioural characteristics were already determinant of baseline stress levels since the first weeks of life. Salivary cortisol was higher in fawns when they were closer to anthropogenic structures and exhibited proactive behaviour. Although fawn phenotype may also be shaped by maternal stress, the small data set of 30 mother-fawns pairs did not enable to show such as relationship. Finally, I showed that the co-variation between immunity and FCMs, depended on individual and environmental characteristics. In a poor environment, high FCMs were related to a low immunity, both for innate and adaptive arms.[...]
Fort, Jérôme. "Réponses des oiseaux marins de l'Arctique aux contraintes environnementales hivernales dans le contexte des changements climatiques". Montpellier 2, 2009. http://www.theses.fr/2009MON20268.
Pełny tekst źródłaHarsh environmental conditions encountered in North Atlantic during wintertime, characterized by frequent extreme weather events, are among the most challenging constraints for endothermic animals. Seabirds, which experience this environment for many months per year, play a central role in North Atlantic food webs, notably as top predators and indicators of marine ecosystems. In the current context of climate change, pronounced in North Atlantic waters, it is therefore a major objective to understand how seabirds respond and adapt to these environmental constraints shaping their survival and their population dynamics. We used a multidisciplinary approach (combining microelectronics, stable isotopic analyses, bioenergetics modelling and demography) focused on individual energy balance, to study the ecophysiological plasticity of the 3 main alcid species of the North Atlantic. We found that harsh winter conditions induce an energetic bottleneck for seabirds which might explain recurrent events of winter mass mortality, so called ‘seabird winter wrecks'. In response to increased energy expenditure, we showed that seabirds can adopt different strategies allowing higher energy intake. They can modulate their vertical (diving behaviour) and/or horizontal (migration) movements, as well as their trophic status, depending on the spatial and temporal availability of their prey. All together, these results constitute one of the first comprehensive studies of seabird winter ecology. These insights are essential to a better understanding of their population dynamics and constitute a firm foundation to future investigations of the impact of climate change on marine top predators
Cheatsazan, Hamed. "Asymptomatic interaction with the fatal amphibian pathogen, Batrachochytrium dendrobatidis : costs, environmental drivers, the outcome and the risk of chytridiomycosis for the palmate newt (Lissotriton helveticus)". Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2350/.
Pełny tekst źródłaThe objective of this thesis was to study the costs, environmental drivers, and the outcome of asymptomatic chytridiomycosis for the palmate newt, Lissotriton helveticus. After reviewing related scientific literature we tested for the impact of subclinical Batrachochytrium dendrobatidis (Bd) infection on condition and sexual traits. We studied the impact of asymptomatic Bd infection on newts' reproductive output, the development and survival of larvae and also considered the impact of environment on sub-lethal costs and host resistance against infection. Finally, the costs and the impact of the infection on a population with a recent, natural Bd exposure were investigated. Collectively, our results show that newts are incurred by sub-lethal costs which impair host's reproduction and survival. Newts that have already been exposed to Bd are found to be tolerant to the infection and can serve as infection reservoir
Pradier, Léa. "Une approche éco-évolutive de la propagation de la résistance antibiotique : l'exemple de la résistance aux aminoglycosides". Thesis, Université de Montpellier (2022-….), 2022. http://www.theses.fr/2022UMONG014.
Pełny tekst źródłaIn front of the antibiotic pressure, a wide range of resistance mechanisms exist. They represent an increasing public health issue, which does and will have major consequences on human mortality. Current strategies —mostly based on antibiotic consumption reductions— globally fail to contain this persistent issue. Moreover, even though it is undeniable that the extensive antibiotic use during the past decades has been a driver of antibiotic resistance evolution, its impact on the emergence and the propagation of antibiotic resistance is often overestimated compared to other factors. First, selection on antibiotic resistance cannot be restricted to the medical and veterinary uses of antibiotics. Second, the evolution (i.e. the emergence, maintenance and spread) of a trait in populations also relies on other evolutionary forces and ecological processes. Finally, the intertwining of these factors induces an intricate evolution of resistant phenotypes, relying on several scales ranging from genetic determinism to environmental dynamics. The aim of this thesis is therefore, through an eco-evolutionary approach, to improve the understanding of forces and mechanisms shaping directions and movements of antibiotic resistance genes. To do so, this thesis focuses on aminoglycoside resistance by modifying enzymes. The results of this work highlight the importance of ecological and genomic factors in the circulation of resistance genes, and thus conclude that integrative studies of resistance are thus required. To begin with, this thesis reveals that the distribution of aminoglycoside resistance is loosely linked to variation in aminoglycoside consumption across Europe, but strongly structured by globalization (trade, migration) and even more by ecological connectivity. Subsequent analysis underscores the underestimated role of non-pathogenic bacteria in the horizontal transfer of antibiotic resistance genes at large phylogenetic scales. In the light of these results, this thesis opens up a course of reflection on the study and management of antibiotic resistance
Vandeputte, Patrick. "Mécanismes moléculaires de la résistance aux antifongiques chez candida glabrata". Phd thesis, Université d'Angers, 2008. http://tel.archives-ouvertes.fr/tel-00433842.
Pełny tekst źródłaVasse, Marie. "Evolutionary ecology of social bacterial populations under antibiotic and bacteriophage pressure". Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS041/document.
Pełny tekst źródłaBacteria are the basis of virtually all ecosystems and examining their dynamics in the face of biotic and abiotic perturbations is essential to understanding their persistence, evolution and diversification. This thesis is directed towards a better understanding of the impact of phage and antibiotic pressure on the evolutionary ecology of bacterial populations and, in particular, on the evolution of bacterial social behaviours. First, using a combination of mathematical modelling and experimental evolution, we studied how antagonisms in the form of antibiotics (Chapters 1 and 2) and phages (Chapter 3) affect the dynamics of public goods production and strategies, and the evolution of resistance in populations of the bacterium Pseudomonas aeruginosa. We found that both phages and antibiotics favour cheats over cooperators in well-mixed environments. While the advantage to cheats leads to population growth and even increased resistance frequency in the short-term (Chapter 1), the cheat-dominated populations eventually declined in the presence of phage predators, arguably due to the combination of antagonist pressure and cheating load (Chapter 3). Second, based on the evolutionary prediction that multiple control agents will be more efficient at controlling bacterial populations and reducing the evolution of resistance, we investigated in vitro the complex interactions between phages and antibiotics in the context of combined therapies. We showed that the combination of phages and antibiotics decreased population survival and resistance evolution significantly more than either alone. While this main result may be mitigated by several factors such as antibiotic dose (Chapters 4 and 5), the timing of inoculation (Chapter 4), and antibiotic mode of action (Chapter 5), it is also obtained in longer-term assays (Chapter 5). Our results highlight the complexity of the interplay between the negative effects exerted by antibiotics and phages and the evolutionary ecology of bacterial populations, and bring new insights both to the understanding of social evolution and for the potential therapeutic use of phages and antibiotics
Paris, Margot. "Evolution de la résistance au bactério-insecticide Bti chez les moustiques". Phd thesis, Grenoble, 2010. http://www.theses.fr/2010GRENV005.
Pełny tekst źródłaMosquito control represents a major public health concern, as mosquitoes transmit many severe human diseases. After the massive use of chemical insecticides since the fifties, the bacterio-insecticide Bacillus thuringiensis subsp. Israelensis (Bti) represents a safe alternative and is now widely used to control mosquito populations. High toxicity due to commercial Bti proliferation and persistence was found in decaying leaf litter collected in mosquito breeding sites. Ln order to evaluate the evolution of resistance, a laboratory Aedes aegypti strain was selected with field-collected leaf litter containing Bti toxins. Resistance of Aedes aegypti to Bti Cry toxins evolved after only few generations of larval selection. Several approaches were used to study the genetic bases of Bti resistance in the resistant strain. First. Two genome scans revealed several genomic regions under selection. Then, a transcriptome scan allowed the comparison of the transcription of more than 6000 between the susceptible and the resistant strain. Several genes potentially involved in Bti resistance were detected by combining these results with a candidate gene approach. Among them, a cadherin gene displayed patterns of nucleotide polymorphisms consistent with the action of positive selection and appeared a good candidate for Bti resistance. Furthermore. Signatures of selection linked to Bti treatment and high gene flow were detected by a population genomic approach in the Rhône-Alpine mosquito strain Aedes rusticus. Information about genetic factors linked to Bti resistance and biological factors linked to treated species are essential to use adapted resistance management strategies
Paris, Margot. "Evolution de la résistance au bactério-insecticide Bti chez les moustiques". Phd thesis, Université de Grenoble, 2010. http://tel.archives-ouvertes.fr/tel-00629116.
Pełny tekst źródłaGhestem, Murielle. "Quelles propriétés racinaires et quelles espèces-outils pour la stabilisation des points chauds de dégradation en Chine du Sud ?" Phd thesis, AgroParisTech, 2012. http://pastel.archives-ouvertes.fr/pastel-00855792.
Pełny tekst źródłaZiegler, Camille. "Diversité des mécanismes de résistance à la sécheresse des arbres en forêt tropicale humide". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0061.
Pełny tekst źródłaTropical rainforests play a central role in biogeochemical cycles at the global scale. Seasonal droughts alter their functioning, but severe droughts can severely affect tree growth and mortality. Increasingly frequent severe droughts in the past decades over the entire Amazon Basin have triggered changes in tree community composition, but our capacity to predict the fate of these communities is partly hampered by our lack of knowledge on the physiological mechanisms involved in tree drought-resistance. This thesis explores the interspecific diversity of drought resistance mechanisms of tropical rainforest tree species in French Guiana and aims at enhancing our present knowledge on their functioning. This thesis reveals that tropical rainforest canopy tree species can be very resistant to drought-induced stem embolism and that a majority of species achieve high hydraulic safety during the dry season, with strong interspecific differences. However, for most trees, a decrease in soil water availability leads to a decrease in their sap flux density during the dry season, with part of their sensitivity being related to physiological mechanisms involved in drought-resistance strategies. The underlying physiological mechanisms to their strategies vary strongly between species for young tree saplings. Some benefit from an early stomatal closure and low minimum leaf conductance, while others are more resistant to stem embolism and rely on a positive hydraulic vulnerability segmentation. During a severe imposed drought, there was a strong reduction in carbohydrate contents, which highlights the interdependence between the water and carbon balance of trees. However, the main physiological mechanism causing tree mortality seems to be hydraulic failure. The strong interspecific variability within these communities could lead to contrasting responses of tree populations to an increase in the frequency and severity of drought events, which could impact tree community composition in French Guiana
Luo, Chen. "Effets écologiques et physiologiques des endosymbiotes facultatifs dans la résistance aux guêpes parasitoïdes et l'immunité des pucerons". Electronic Thesis or Diss., Université Côte d'Azur (ComUE), 2019. http://theses.univ-cotedazur.fr/2019AZUR6019.
Pełny tekst źródłaSymbiosis is omnipresent in nature. In these intimate and prolonged associations between different organisms, the effect of gene expression from one partner on the other can lead to the appearance of new phenotypes, a concept called "extended phenotype". My thesis focuses on the study of host-parasitoid-symbiont interactions in aphids, mainly the pea aphid Acyrthosiphon pisum, which has become a model for its obligatory nutritional symbiosis with Buchnera aphidicola and facultative with one or more symbiotes, the most common being Hamiltonella defensa (Hd), Regiella insecticola (Ri) and Serratia symbiotica (Ss). My work addresses ecological and physiological aspects of facultative symbiosis in aphids. Aphids are hosts for a complex community of parasitoids that fit in the Performance-Preference Hypothesis (PPH) suggesting that females will preferentially lay eggs in hosts that maximize the survival and performance of their offspring. The PPH evaluation classifies parasitoids in terms of degree of specialization. I participated in the determination of the PPH of three parasitoids (Aphelinus abdominalis, Aphidius ervi and Diaeretiella rapae) using 12 aphid species (6 Aphidini and 6 Macrosiphini) maintained on different host plants and whose symbiotic status was established. A. abdominalis and D. rapae appeared as generalists and A. ervi as a moderate specialist. All species showed low selectivity towards the host regardless of the host plant or symbiont, but parasitic success was impacted by some symbionts. I then studied the effect of host genotype, genotypes (host x symbiont) on parasitoid success using artificially infected clones of the aphid Sitobion avenae with a protective strain of Ri. Infected lines are better hosts for Aphelinus asychis but not Aphidius gifuensis, compared to the same infection-free clones. The Ri effect is therefore dependent on the parasitoid species, indicating that the cost/benefit of a symbiont is context-dependent. In the second part of my thesis, I focused on the host's immune system as a central aspect in the establishment and evolution of interactions between organisms. The annotation of different aphid genomes shows a reduced immunity that could be due to their adaptation to a symbiotic life. Hemocytes and phenoloxidase activity, two major immune components, have been described in aphids. I have developed molecular tools to analyze the expression of genes encoding both phenoloxidases (PO) of A. pisum (PO2 and PO2-X1) and to estimate their amount in the hemolymph. I used clones from different genetic backgrounds without secondary symbiont (LL01, YR2-Amp, T3-8V1-Amp) and natural or artificial lines YR2 or T3-8V1 infected with Hd, Ri or Ss. I have demonstrated that: i) both genes are expressed and their products are present in circulating form in the hemolymph, ii) gene expression, amount and activity of PO are highly correlated and depend on the genetic background of the host and iii) these three markers are significantly decreased by the presence of Hd and Ri. I observed a correlation between the impact of stressors on the aphid's life traits and the presence of some symbionts (and therefore the amount of PO in aphids), but no correlation with the variation in PO after stress. This work therefore shows a strong interaction between the host's immune capacity and the symbiotic status of the aphid, and can explain the success or failure of some parasitoids that are not highly specialized for the host they attack
Aura, Christophe. "Les politiques d'échelles de la campagne de Greenpeace Canada dans la forêt boréale du Québec : une analyse en political ecology". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37203.
Pełny tekst źródłaSeimandi, Corda Gaëtan. "Recherche de nouveaux leviers pour cribler la résistance du colza (Brassica napus) au méligèthe (Brassicogethes aeneus) : de la métabolomique au champ". Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1B012/document.
Pełny tekst źródłaHerbivorous insects cause important yield losses to crops. These insects are mainly managed through insecticides but negative effects of used compounds on the human health and the environment as well as the development of resistant pest populations impose finding alternative strategies to manage them. Breeding plants for enhanced resistance to insects is an attractive strategy. This kind of strategy was already implemented to manage insects but examples of its utilisation remain rare. The main limitation of this strategy is that a large number of genotypes needs to be screened through generally complex phenotyping methods to identify resistances. To circumvent these issues, an approach based on the understanding of plant defence mechanisms and the utilisation of biochemical biomarkers linked to resistance could be interesting. During this PhD, this kind of approach was developed on the oilseed rape (Brassica napus) and one of its main pests, the pollen beetle (Brassicogethes aeneus). Previous studies identified chemical compounds present in the perianth of flower buds and correlated to oilseed rape resistance to pollen beetle. However these studies were carried out in the laboratory and need to be validated in field conditions. Moreover, information on pollen beetle feeding ecology are still lacking while they could help identifying new targets for breeding. The first objective of this PhD is to develop a method allowing to screen resistance to the pollen beetle in the field. This method will allow to confirm the potential biomarkers previously identified and to look for additional biomarkers. The second objective of the present work was to better understand key steps in the interaction between the pest and its host plant to identify potential new target traits for resistance. For this purpose, the importance of food sources present in flowers such as pollen and nectar on pollen beetle development and the factors impacting the feeding pattern of adults on the inflorescence were investigated. We conducted field experiments in two different sites and for two consecutive years and propose a method allowing to screen oilseed rape resistance to pollen beetle in the field. Using this method, we were able to identify genotypes with moderate levels of resistance among a set of 19 genotypes. Previously identified biochemical biomarkers were not correlated with plant resistance in the field but new markers were identified (i.e. quinic acid and arginine). Our field experiments also showed that plant composition is highly variable according to the environment and this variability could affect usefulness of these markers during plant breeding programs. Experiments under controlled conditions also showed that pollen beetle used nectar for feeding but that it did not seem to affect its development. Pollen, on the other hand, seemed to have a more important impact but was not indispensable to pollen beetle development. The study of the pollen beetle feeding behaviour showed that this insect has a surprising feeding pattern on oilseed rape inflorescences and that small buds are more used for feeding than large buds that contain more pollen. It seems that accessibility and to a lesser extend availability of feeding resource explain this pattern and that the perianth has a major role on this preference. These experiments allowed to better understand the pollen beetle feeding ecology and to identify plant traits important for its development. Our work showed that moderate levels of resistance are present in oilseed rape and could be used in breeding programs. Limitations of approaches based on biochemical biomarkers are discussed
Dubuffet, Aurore. "Variation intra spécifique de résistance et de virulence dans un système hôte-parasitoïde : Approche intégrative de la spécificité des interactions". Phd thesis, Université François Rabelais - Tours, 2006. http://tel.archives-ouvertes.fr/tel-00101898.
Pełny tekst źródłaLe travail de thèse présenté ici porte sur les variations de virulence du parasitoïde et les variations de résistance de l'hôte à l'origine de variations dans l'issue du parasitisme dans le modèle Leptopilina boulardi - Drosophila yakuba. Deux lignées du parasitoïde L. boulardi, présentant des capacités de virulence contrastées vis à vis de l'hôte D. yakuba, ont été étudiées et comparées pour leur comportement de sélection d'hôte et leur stratégie de virulence. Les résultats obtenus suggèrent une relation entre capacités de virulence et comportement de choix d'hôte chez L. boulardi et démontrent l'existence chez une même espèce de parasitoïde de stratégies parasitaires différentes utilisées contre deux espèces hôtes. Les effets physiologiques du parasitisme sur l'immunité de l'hôte sont décrits et l'étude de la nature des facteurs de virulence est abordée. Les bases génétiques et physiologiques de la variation de résistance à L. boulardi chez l'hôte D. yakuba ont été par ailleurs étudiées à l'aide de deux lignées hôtes respectivement sensible et résistante.
L'ensemble des données obtenues au cours de cette thèse ont été comparées avec les données disponibles dans le modèle L. boulardi - D. melanogaster dans une approche permettant d'aborder les problèmes de spécificité d'hôte au niveau physiologique et moléculaire.
Travadon, Renaud. "Facteurs épidémiologiques contribuant à l'adaptation des populations de Leptosphaeria maculans aux résistances spécifiques de Brassica napus : dispersion des pycnidiospores et des ascospores et progression systémique du champignon". Phd thesis, Agrocampus - Ecole nationale supérieure d'agronomie de rennes, 2008. http://tel.archives-ouvertes.fr/tel-00333477.
Pełny tekst źródłaDERAISON, Céline. "Isolement, caractérisation et cibles de nouveaux Inhibiteurs de protéases pour la création de plantes transgéniques résistantes aux pucerons". Phd thesis, Université Paris Sud - Paris XI, 2002. http://tel.archives-ouvertes.fr/tel-00006629.
Pełny tekst źródłaCette étude a pour objectif d'accroître la disponibilité des gènes d'IP originaux et d'en comprendre le mode d'action afin d'en maîtriser l'introduction raisonnée dans les programmes de lutte variétale.
Au cours de ce travail de thèse, des informations sur la protéolyse digestive des Homoptères ont été apportées : des protéases à cystéine, les cathepsines (enzymes lysosomiales) sont spécifiquement exprimées dans le tube digestif et dans un organe spécialisé, le bactériocyte. Elles sont la cible potentielle d'inhibiteurs de protéases à cystéine. Lorsque l'Oryzacystatine (inhibiteur de protéase à cystéine, isolé du grain de riz) est exprimé dans le colza, la fécondité du puceron Mysus persicae diminue de 25%. Ce résultat démontre qu'il est donc possible d'exprimer des IP dans le phloème pour lutter contre les pucerons. L'amélioration, par mutagenèse dirigée, d'un inhibiteur de protéases à sérine, isolé du pois, a aussi été effectuée mais son expression hétérologue dans Pichia pastoris ou Arabidospsis thaliana n'a pas permis d'obtenir une forme active.
Nous avons cherché à élargir le pool de gènes disponible pour lutter contre les pucerons. L'isolement d'un inhibiteur de protéases à cystéine de l'hémolymphe du puceron a été entrepris au niveau moléculaire et biochimique. Ces résultats démontrent que les IP constituent une nouvelle voie pour lutter contre les pucerons.
Jardim, Arruda André. "Seed ecology and grassland resilience : the case of campo rupestre How have we studied seed rain in grasslands and what do we need to improve for better restoration?" Thesis, Avignon, 2019. http://www.theses.fr/2019AVIG0353.
Pełny tekst źródłaOur knowledge of tropical old-growth grassland resilience (i.e. resistance to degradation and capacity for recovery) remains limited relative to our knowledge of temperate grasslands. Although highly resilient to endogenous disturbances such fires, the vegetation dynamics in old-growth fire-prone tropical grasslands seems hampered by anthropogenic disturbances, especially topsoil degradation. After topsoil disturbance, the internal species pool (i.e. remaining vegetation and the seed bank) is often depleted or even absent, and natural regeneration depends mainly on seed dispersal from surrounding sites via the seed rain. However, plant communities on areas disturbed by soil removal can remain very different from preserved sites many years after degradation, with almost no recovery of the natural vegetation. Despite extremely relevant, seed dispersal dynamics and resilience of tropical old-growth grasslands after soil disturbance remains much overlooked. In this thesis, I carried out a review and three experimental studies about seed rain and diaspore removal dynamics in grasslands. In CHAPTER1, I did a systematic literature survey about seed rain studies in global grasslands. I (1) assessed where, how and why research on seed rain has been carried out; (2) examined how methodological design and results have been reported; and (3) provided guidelines for future research on seed rain in grasslands. I found a remarkable unbalance in the numbers of studies between grassland types, which becomes even more dissimilar across global climatic ranges when the area covered by each grassland type is take into consideration. I identified significant knowledge gaps in grassland seed rain research. I also found a great disparity of methods and data being reported across studies. Additionally, I found that only a few attempts have been made to assess the seed trap efficiency and no studies to date have proposed any protocol to evaluate the effectiveness of seed sorting methods. Then, in CHAPTER 2, I ran a field experiment to propose a simple standard protocol to evaluate the efficiency of two seed trap types (sticky and funnel traps) and of a seed sorting method to assess the efficient of the methods prior to seed rain studies. As a case of study, in CHAPTER 3 and 4, I studied seed rain and secondary diaspore removal dynamics in preserved areas and in areas degraded by gravel exploitation for road construction in campo rupestre vegetation, a megadiverse edaphic grassland in southeastern Brazil. The small number of seeds captured in the seed rain, indicates seed limitation and suggests a close causal relationship between seed dispersal limitation and the low resilience after soil disturbance. The identification of some relatively abundant species in the seed rain places these species as good targets for reintroduction in future restoration projects. Topsoil removal changed the identity of ants interacting with diaspores, resulting in contrasting outcomes from ant-diaspore interactions. The lack of diaspore removal towards degraded areas indicates that establishment limitation is a factor hampering natural regeneration. Our findings help to explain, at least partially, why natural regeneration is compromised after soil removal, which strongly influences diaspore fate and interactions with potential ground-dwelling dispersers, resulting in different ecological outcomes and strong influencing vegetation dynamics and regeneration. I expect that these results will guide future research on seed dispersal and resilience in grasslands, underpinning decisions on restoration and conservation practices on these threatened environments
O nosso conhecimento sobre a resiliência (isto é, resistência à degradação e capacidade de recuperação) de savanas tropicais permanece muito aquém do nosso conhecimento já adquirido sobre as savanas temperadas. Savanas tropicais, embora altamente resilientes à perturbações endógenas, como o fogo, se mostram extremamente vulneráveis à certas perturbações antrópicas como a degradação do solo, a quais podem ocasionar drástica alteração da dinâmica da vegetação. Após a perturbação da camada superficial do solo, o conjunto interno de espécies (isto é, a vegetação remanescente e o banco de sementes) são frequentemente reduzidos ou até mesmo completamente eliminados. Nestes casos, a regeneração natural depende principalmente da dispersão de sementes da vegetação do entorno através da chuva de sementes. No entanto, comunidades vegetais em áreas perturbadas pela remoção do solo podem permanecer, mesmo após vários anos ao distúrbio original, muito diferentes do ecossistema de referência, apresentando baixíssima capacidade de regeneração natural. A dinâmica de dispersão de sementes em savanas tropicais, apesar de extremamente relevantes para uma melhor compreensão sobre a resiliência desses ecossistemas frente a ações antrópicas, permanece pouco estudada. Nesta tese, realizei uma revisão e três estudos experimentais sobre a dinâmica da chuva de sementes e da remoção de diásporos no campo rupestre, uma savana tropical natural, megadiversa e muito antiga localizada no sudeste do Brasil. No primeiro capítulo, realizei uma pesquisa bibliográfica sistemática sobre estudos de chuva de sementes em áreas não florestais no mundo com os seguintes objetivos: (1) avaliar onde, como e por que as pesquisas sobre chuva de sementes foram realizadas; (2) examinar como o desenho metodológico e os resultados foram relatados; (3) fornecer diretrizes para futuras pesquisas sobre chuva de sementes em áreas não florestais. Nesta revisão, eu encontrei um notável desequilíbrio no número de estudos entre os tipos diferentes tipos de áreas não florestais, o qual se torna ainda mais notável em relação à distribuição dos estudos entre as faixas climáticas globais e em relação à área total recoberta por cada ecossistema (ex. savanas tropicais). Neste estudo, foram identificadas algumas importantes lacunas de conhecimento relativas a estudos sobre a chuva de sementes em áreas não florestais. Foi evidenciado também uma grande disparidade entre os métodos de estudo de chuva de semente e sobre a maneira de reportar os dados observados, o que dificulta comparações entre estudos. Verificamos que apenas algumas tentativas foram feitas para avaliar a eficiência das armadilhas de captura de sementes e que nenhum estudo até o momento propôs algum protocolo para avaliar a eficácia dos métodos de captura de sementes utilizando armadilhas de sementes para áreas não florestais. No segundo capítulo, foi proposto e testado um protocolo simples para avaliar a eficiência de dois tipos de armadilhas de sementes (armadilhas pegajosa e de funil) e a eficácia de um método de busca e triagem de sementes coletas em armadilhas de funil, os quais podem ser realizados previamente aos estudos de chuva de semente. Como casos de estudo, no terceiro e quarto capítulos, pesquisei a dinâmica da chuva de sementes e de remoção secundária de diásporos em áreas preservadas e em áreas degradadas pela exploração de cascalho para a construção de estradas na vegetação do campo rupestre. O pequeno número de sementes capturadas na chuva de sementes indica limitação na dispersão de sementes e sugere uma estreita relação causal entre a limitação de dispersão de sementes e a baixa resiliência observada nestas áreas degradadas após a perturbação do solo.A identificação de espécies relativamente abundantes na chuva de sementes coloca essas espécies como potenciais alvos para futuros projetos de restauração visando a reintrodução de espécies
Ségurel, Laure. "Mode de vie et diversité génétique dans les populations humaines d'Asie Centrale". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00547600.
Pełny tekst źródłaAlvarado, Swanni Tatiana. "Evaluation du rôle des feux de brousse sur la composition, la structure, la phénologie, et la résistance de la végétation des bois de tapia (Uapaca bojeri) du massif d’Ibity, Nouvelle Aire Protégée, en vue de sa gestion durable". Thesis, Avignon, 2012. http://www.theses.fr/2012AVIG0323/document.
Pełny tekst źródłaCurrently loss and transformation of habitats are the main threats which cause the decrease of biological diversity. In Madagascar, 90% of plants species are endemic of the island and most of the plant formations types are at present strongly degraded or replaced by secondary formations resulting from human activities. Tapia woodland, dominated by the endemic tree Uapaca bojeri, is a sclerophyllous vegetation type limited in the Malagasy highlands. This vegetation type, adapted and resistant to the natural fire regime, is very fragmented today, covering a surface equivalent to 132 255ha on the island. In order to increase the protection of tapia woodland, a new protected area was established on Ibity massif. The current state of the woody vegetation is the result of the interaction of some factors as soil type, climate, human traditional practices and fire. Although fire is one of the phenomena that determine the dynamics of this vegetation, the current fire regime is also one of the main causes of degradation. The objective of this thesis is to study the role of fire on the demographic cycle and on some main processes for installation and recruitment. Thus, germination, plant phenology and seedlings resistance after burnt were studied. This research shows that the current problem of tapia woodland are 1) the reduction of flowering and fruiting by high fire frequencies; 2) the reduction of germination percent after seed exposure with high temperatures, and 3) high seedlings mortality after burnt, in particular when the quantity of fuel is raised. Installation and recruitment of woody species are limited by fire, which has a negative effect on natural regeneration. Fire management around the protected area is thus necessary for its conservation
Guénon, René. "Vulnérabilité des sols méditerranéens aux incendies récurrents et restauration de leurs qualités chimiques et microbiologiques par des apports de composts". Phd thesis, Université Paul Cézanne - Aix-Marseille III, 2010. http://tel.archives-ouvertes.fr/tel-00555463.
Pełny tekst źródłaRebaudet, Stanislas. "Epidémiologie moléculaire et génétique des populations de Plasmodium falciparum dans l'archipel des Comores. Implications pour la lutte antipaludique". Phd thesis, Université de la Méditerranée - Aix-Marseille II, 2009. http://tel.archives-ouvertes.fr/tel-00514306.
Pełny tekst źródłaSauvion, Nicolas. "Effets et modes d'action des deux lectines à mannose sur le puceron du pois, Acyrthosiphon pisum (Harris) - Potentiel d'utilisation des lectines végétales pour la création de plantes transgéniques résistantes aux pucerons". Phd thesis, INSA de Lyon, 1995. http://tel.archives-ouvertes.fr/tel-00007006.
Pełny tekst źródłaLes caractéristiques toxicologiques de nombreuses protéines sont évaluées par des tests d'ingestion sur milieux artificiels définis. Des lectines d'origine végétale se liant au mannose présentent des propriétés toxiques intéressantes. Notre étude porte sur la Concanavaline A (lectine de Canavalia ensiformis [L.] DC, ConA) qui est une lectine modèle très étudiée du point de vue biochimique, et la lectine du perce-neige (Galanthus nivalis L., GNA) dont les caractéristiques en font un bon candidat à l'application envisagée.
Nous mettons en évidence une variabilité de la toxicité des lectines à mannose chez six espèces de pucerons. La ConA est moins active sur les espèces polyphages. Elle n'est pas phagorépulsive pour notre puceron modèle, Acyrthosiphon pisum (Harris) et agit en quelques heures aux doses moyennes, notamment en inhibant l'ingestion. Une adaptation comportementale à moyen terme (24 h-48 h) est également mise en évidence. Des techniques de marquage révèlent que la cible physiologique primaire de la ConA est la portion antérieure du mésentéron. Elle s'y fixe en très grande quantité. Après liaison aux cellules épithéliales, la lectine induit une hypertrophie de ces cellules et un détachement de leur membrane apicale. Des expériences de compétition lectines/mannosides indiquent que la liaison toxine-épithélium ne semble pas dépendre uniquement d'une interaction sucre-lectine. Nous observons également une forte perturbation du métabolisme des acides aminés des pucerons. Le mode d'action de la ConA et de la GNA diffèrent sensiblement sur ce point.
Les premiers tests biologiques effectués sur des pommes de terre transgéniques exprimant de manière constitutive le gène de la GNA sont variables mais prometteurs.
Mansos, Lourenço Marta. "Deciphering in vivo efficacy of virulent phages in the mammalian gut". Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS260.pdf.
Pełny tekst źródłaThe mammalian gut is a heterogeneous environment inhabited by a large and diverse microbial community, including bacteria and their viral predators, bacteriophages (phages). Dynamic interactions between virulent phages and bacteria in the gut are still poorly understood, which is also an obstacle for the design of successful therapeutic interventions based on phages. Independent experiments have shown that virulent phages were found to have no major effects on their targeted bacteria in the gut, in spite of sustainable phage amplification. This suggests that there are unknown factors in the gut environment that modulate these interactions. Using comparative transcriptomics analysis of E. coli grown in vitro and in vivo (within the mammalian gut) we found that in the gut, bacteria downregulate the expression of genes related to phage receptors, which provides an explanation for the lack of selection of phage-resistant bacteria during in vivo experiments. We also found that the acquisition of a pathogenicity island commonly found in human E. coli isolates affects phage susceptibility possibility by downregulating a defense mechanism against invading DNA. Finally, we examined the repartition of phages and bacteria through mucosal and luminal gut sections and observed a heterogeneous spatial distribution of these two antagonist populations, supporting the hypothesis of source-sink dynamics. Altogether our data demonstrates that multiple factors encompassing, spatial distribution, bacterial physiology and defenses against foreign DNA modulate the interactions between bacteria and phages within the gut
Montarry, Josselin. "Réponse adaptative des populations de Phytophthora infestans, agent du mildiou de la pomme de terre, au déploiement en culture de son hôte Solanum tuberosum". Phd thesis, Agrocampus - Ecole nationale supérieure d'agronomie de rennes, 2007. http://tel.archives-ouvertes.fr/tel-00133363.
Pełny tekst źródłaGoudard, Alexandra. "Fonctionnement des écosystèmes et invasions biologiques : importance de la biodiversité et des interactions interspécifiques". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00154719.
Pełny tekst źródłaIbanez, Thomas. "Dynamiques des forêts denses humides et des savanes en réponse aux incendies en Nouvelle-Calédonie". Phd thesis, Aix-Marseille, 2012. http://tel.archives-ouvertes.fr/tel-00681865.
Pełny tekst źródłaCaillon, Robin. "Biogéographie du microclimat foliaire : mécanismes et conséquences sur les relations plantes-insectes". Thesis, Tours, 2016. http://www.theses.fr/2016TOUR4006/document.
Pełny tekst źródłaPlant performance and leaf-dwelling arthropods are impacted by leaf surface temperatures. Leaf surface temperatures can show important deviation from air temperature and present different levels of heterogeneity depending on the spatial scale. The leaf buffers temperature extremes by getting closer in amplitude to air temperature. However, this physiological response decreases the heterogeneity of temperatures at the leaf surface and the opportunities for arthropods to behavioraly thermoregulate in this microclimate. Mean temperatures at the leaf surface show low buffering abilities in response to warming and locally determine photosynthetic performance. From the leaf to the canopy scale, plants show different responses to warming and scaling is crucial to increase our understanding of the impact of global warming
Falardeau, Audrey-Maude. "« Vite, ralentissez ! » : enjeux identitaires, temporels et matériels des slow mags dans l’écologie médiatique québécoise". Thèse, 2018. http://hdl.handle.net/1866/22463.
Pełny tekst źródłaLemieux-Labonté, Virginie. "Microbiome cutané et maladie fongique émergente du syndrome du museau blanc chez les chauves-souris d’Amérique du Nord". Thesis, 2020. http://hdl.handle.net/1866/25580.
Pełny tekst źródłaWhite-nose syndrome (WNS) caused by the fungus Pseudogymnoascus destructans (Pd) has put hibernating bat populations at risk in North America. Some species are highly vulnerable to the disease while other species appear to be resistant or tolerant. Several physiological and environmental factors can explain these differences. However, before 2015, few studies have focused on the skin microbiome in relation to this disease. The present thesis aims to characterize the cutaneous microbiome of bats affected by WNS in order to identify the factors of vulnerability or resistance to the disease. The main objective is to determine how the microbiome can protect against the Pd fungus, or conversely how the microbiome is altered by the fungal infection. In Chapter 1, we first explored and compared the skin microbiota of little brown bats (Myotis lucifugus) unaffected by WNS with that of WNS survivors to test the hypothesis that the skin microbiota is modified by the disease. Our results show that the hibernation site strongly influences the composition and diversity of the skin microbiota. The Pd positive and negative sites differ significantly in terms of diversity, as well as in terms of the composition of the microbiota. Diversity is reduced within the microbiota of bats surviving WNS and enriched in taxa such as Janthinobacterium, Micrococcaceae, Pseudomonas, Ralstonia, and Rhodococcus. Some of these taxa are recognized for their antifungal potential and specific strains of Rhodococcus and Pseudomonas may inhibit the growth of Pd. Our results are consistent with the hypothesis that Pd infection modifies the skin microbiota of surviving bats and suggest that the microbiota may play a protective role against WNS. In Chapter 2, we studied in a controlled environment the microbiota of a species that exhibits evidence of resistance with mild WNS symptoms, before and after infection, to establish the potential response to the disease. The species studied is the big brown bat (Eptesicus fuscus), whose skin microbiota could play a protective role against infection. Our results show that the diversity of the microbiota of big brown bats inoculated with Pd is more variable over time, while the diversity of the microbiota of the control bats remains stable. Among the most abundant taxa, Pseudomonas and Rhodococcus, two taxa known for their antifungal potential against Pd and other fungi, remained stable during the experiment. Thus, although inoculation with the Pd fungus destabilized the skin microbiota, bacteria with antifungal properties were not affected. This study is the first to demonstrate the potential of the skin microbiota of a bat species for resistance to WNS. In Chapter 3, the skin microbiome of the little brown bat was evaluated in the natural environment in the context of WNS, using metagenomics, a higher-resolution approach to observe the functional potential of the microbiome (functional metagenome). Our results established that the time since infection has a significant effect on the functional metagenome. Indeed, bats in the first year after infection have a disrupted functional metagenome that undergoes a significant loss of functional diversity. However, the functional metagenome returns to a similar structure and composition to that observed before infection after 10 years. Certain functions detected following infection are associated with genes linked to the transport and assimilation of metals, known limiting factors for the growth of the fungus. These genes could therefore have a role to play in resistance or vulnerability to the disease. Overall, this metagenomics study indicates functional metagenome vulnerability to the fungus, although the original functional metagenome is reestablished after 10 years. Such diversified response could impact M. lucifugus resilence. This thesis provides fundamental knowledge on the skin microbiome of hibernating bats to better understand the microbial communities of the skin in the context of WNS. The microbiome could indeed play a role in the vulnerability and resistance of bats to disease and it is essential to adapt our way of approaching the protection of these species and their microbiomes. We hope that the results of this thesis will raise awareness among conservation stakeholders about the existence and potential importance of the microbiome for the health of its host. This thesis also reports on the advancement of analytical methods that will make it possible to be more and more precise and to apply knowledge of the microbiome in conservation biology.