Rozprawy doktorskie na temat „Herbivores – Alimentation”
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Kopp, Dorothée. "Les poissons herbivores dans l'écosystème récifal des Antilles". Antilles-Guyane, 2007. http://www.theses.fr/2007AGUY0168.
Pełny tekst źródłaThe degradation of coral reefs is currently under investigation in many ecology studies. The present work provides information about the role herbivorus fishes for the reef community and allows to estimate the importance of these fises for the resilience of the benthic coral communities. The herbivorous fish assemblage was studied by scuba diving with quantitative visual censuses in several reef flats and slopes of Guadeloupe. The collected data were processed using several community descriptors, ordination and cluster analyses and autocorrelograms. The study of the temporal variations showed that the herbivorous fish assemblage is submitted to fluctuations during the year but does not follow a seasonal pattern and that some ecological descriptors influence the community such as the swell. The wind and the tide. The study of spatial distribution showed a separation of herbivorous fish assemblages according to depth, with a shallow water fish assemblage distinct from that living on the reef slope. The ecological descriptors responsible for the spatial distribution of herbivorous fishes are the type of algal assemblages, coral cover, depth and the status of reef protection. The fish algal consumption evaluated on the reef revealed that herbivores are not able to regulate. The algal growth when they are overfished. The attraction for different algal facies(turf,rubble,Brown algae,calcified chlorophyta) estimated bymeasuring fish bites,showed that fishes avoid grazing on bottoms dominated by brown algae
Doiron, Madeleine. "Impacts des changements climatiques sur les relations plantes-herbivores dans l'Arctique". Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25487.
Pełny tekst źródłaWhen species at different trophic levels respond to climate change at different rates, this may lead to a trophic mismatch between the phenology of consumers and that of their resources. As polar regions are warming more rapidly than the rest of the planet, migratory birds breeding in the Arctic are expected to be among the species most affected by trophic mismatch in the wake of rapid climate change. This study examines the impact of climate warming on the interactions between an arctic herbivore, the greater snow goose (Chen caerulescens atlantica), and its food plants on Bylot Island, Nunavut, Canada. Using small greenhouses, we examined the impact of increased temperatures on plant biomass and a proxy of nutritive quality, nitrogen concentration, of graminoid plants used by geese during the brood-rearing period. This experiment showed that annual warming significantly increased biomass of graminoids but also led to an acceleration of the seasonal decline in plant nutritive quality and resulted in a decrease in the nitrogen concentration of plants by up to 14% during the period of gosling growth. We also showed that satellite-derived Normalized Difference Vegetation Index (NDVI) can be used as a proxy to determine date of peak nitrogen concentration in some tundra plants, and can thus be a reliable measure of the early changes in the timing of the availability of high quality food for herbivores. Using NDVI, we were then able to estimate the date of peak nitrogen in years when we had no empirical data on plant phenology. Finally, we analysed long-term data on climate, plant phenology and the reproduction of geese in order to examine the potential impact of mismatched reproduction on the growth of young. We found that geese are only partially able to adjust their breeding phenology to compensate for annual changes in the timing of high quality food plants, and that gosling body mass and structural size at fledging was reduced when trophic mismatch was high. Our results support the hypothesis that trophic mismatch can negatively affect the fitness of arctic herbivores, and that it is likely to be exacerbated by rising global temperatures.
Morellet, Nicolas. "Des outils biométriques appliqués aux suivis des populations animales : l'exemple des cervidés : vers un indice de consommation de la flore lignifiée". Lyon 1, 1998. http://www.theses.fr/1998LYO10281.
Pełny tekst źródłaBarrere, Julien. "Interactions entre chêne et cervidés durant le processus de renouvellement - cas des peuplements forestiers tempérés de plaine (Quercus robur et Q. petraea)". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0285.
Pełny tekst źródłaThe abundance and spatial distribution of cervids have drastically increased in France, and more generally in the Northern hemisphere over the last decades. These species play a crucial part in the functioning of forest ecosystems, but the current level of their populations compromises the process of forest regeneration for many tree species of crucial importance such as pedunculate and sessile oak (Quercus robur et Q. petraea). The objectives of this thesis are to quantify and unravel the mechanisms underlying the constraint exerted by cervids on oak regeneration through the consumption of acorns, of oak saplings and of admixed understory species, and (ii) to identify how specific forest management operations (i.e. fencing, felling, and clearing) can limit or enhance this constraint. The analysis of a long-term dataset of red and roe deer rumen content sampled in the study site of La Petite Pierre (Northeastern France) showed that acorns represented a significant resource in the diet of these two species, but that their acorn consumption saturated years of high fructification. Using experimental approaches, we showed that simulated deer browsing on the apical shoot systematically reduced oak sapling height growth both in situ and ex situ, and this was explained by a relatively poor plasticity in resource allocation following browsing to compensate for the loss of tissues. The analysis of a network of fenced-unfenced plots located in several sites in France and in Sweden showed that felling to increase canopy openness enhanced the negative effect of cervids on oak sapling growth and survival through a higher frequentation of cervids under open canopies. Lastly, after implementing the process of herbivory in a forest dynamic model (i.e. Regeneration library of CAPSIS modelling tool), I conducted simulations that suggested that under a high browsing pressure, less frequent clearing operations maintaining highly palatable sapling species such as hornbeam could reduce the negative influence of cervids on oak regeneration. To conclude, this thesis results confirm that cervids exert a significant constraint on the process of oak regeneration, but also suggest that adapted management of the understory vegetation could reduce this constraint and contribute to restore a balance between wildlife and silvicultural activities
Bison, Marjorie. "Approches taxonomique et fonctionnelle des interactions trophiques entre grands herbivores et communautés végétales dans un écosystème de montagne". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAV068/document.
Pełny tekst źródłaGiven the key role of large herbivores on species and functional plant diversity, we aimed at better understanding the relationship between herbivory and plant communities mainly at a fine-scale, in order to reconcile objectives of population management and plant conservation. For this purpose, we used both taxonomic and functional approaches, and studied interactions at the inter- and intra-specific levels. We combined information coming from three databases: (1) diet data from DNA-metabarcoding applied on chamois (Rupicapra rupicapra), roe deer (Capreolus capreolus) and mouflon (Ovis gmelini musimon) faeces from the Bauges Massif, (2) characteristics of plant communities (plant composition, biomass, phenology), (3) plant functional traits. Analyses of intra-specific variability of the three large herbivores allowed us to upscale the niche variation hypothesis (NVH) of Van Valen from the intra- to the inter-specific level, i.e. we observed a positive relationship between the species niche breadth and among-individual variation. Then, based on two chamois subpopulations living in pastures, one living in sympatry with the mouflon and the other living in allopatry, we revealed the absence of negative effects of the introduced mouflon population on native chamois population diet, both for the taxonomic and functional dietary niche. Analyses of diet selection criteria allowed us to highlight differences in choice criteria between chamois and mouflon in some seasons, which helped to explain the taxonomic and functional niche partitioning of the two species. Furthermore, the proposed scenario of the evolution of diet selection over the year for both species were consistent with ungulate-specific morpho-physiological features. Finally, contrary to the literature where no studies could discriminate the direct and indirect effects of functional traits on diet selection because of correlations, we used path analyses, which allowed us to show that in most cases, biomechanical traits had a direct effect on diet choices, whereas chemical traits had an indirect effect. Furthermore, from a methodological point of view, we advised to use nitrogen fecal indices only to study the evolution of species-specific and location-specific population long-term diet quality, but not to compare diet quality between species, nor to study slight fluctuations at the intra-seasonal level. The complementarity of the approaches allowed us to better account for the structuration of herbivore communities, which should help to better assess the actual state and the evolution of relationships among individuals, species and their environment.Key-words: ungulates, intra- and inter-specific interactions, taxonomic and functional approach, DNA metabarcoding, NIRS, Bauges Massif, diet selection
Dromard, Charlotte. "Niches trophiques des poissons herbivores des Antilles : apports des isotopes stables". Thesis, Antilles-Guyane, 2013. http://www.theses.fr/2013AGUY0597/document.
Pełny tekst źródłaHerbivorous fishes play a major ecological role against the « coral-algal phase-shift » phenomenon in the coral reefs of the Caribbean. In this study, the feeding patterns of the most important species of herbivorous fishes have been studied to understand how these species use and share the trophic resources on reefs and seagrass beds . Trophic niches of these species have been described by two complementary methods: the analyses oftheir digestive contents and the analyses of stable isotopes of carbon C3C/ J2C) and nitrogen (lsN/14N). The nutritional quality of the sources has been evaluated by their concentrations of macronutrients (proteins, lipids, soluble and insoluble carbohydrates) to explain partially the choice of resources by herbivorous fishes . Among the 14 studied species of herbivorous fishes (Pomacentridae, Acanthuridae and Scaridae), eight types of trophic niches have been described, indicating a functional diversity of these species . The trophic niches are occupied by one or several species, independently oftheir morphology or their taxonomie affinities. The results of this study suggest a complementarity among these species and raise the question of their conservation to preserve their ecological role on marine ecosystems of the Caribbean
Louguet, Sophie. "Les très grands herbivores (éléphantidés et rhinocérotidés) au Paléolithique moyen en Europe du Nord-Ouest : Paléoécologie, taphonomie et aspects palethnographiques". Lille 1, 2004. https://pepite-depot.univ-lille.fr/RESTREINT/Th_Num/2004/50377-2004-36.pdf.
Pełny tekst źródłaCourant, Sabrina. "Maximiser ses gains énergétiques dans un monde hétérogène : un exemple chez un grand herbivore grégaire, le bison des plaines". Thesis, Université Laval, 2012. http://www.theses.ulaval.ca/2012/28931/28931.pdf.
Pełny tekst źródłaGlasser, Frédéric. "L'influence des facteurs externes sur la reproduction de la carpe herbivore (Ctenopharyngodon idella) en zone tropicale : une approche descriptive et expérimentale". Rennes 1, 2003. http://www.theses.fr/2003REN10016.
Pełny tekst źródłaGiroux, Marie-Andrée. "Comment un herbivore surabondant bénéficie des ressources dépendantes, indépendantes ou découplées de la pression de broutement". Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25364.
Pełny tekst źródłaHerbivores can induce major modifications to plant communities that can reduce forage abundance and lead to a retroaction between the size of herbivore populations and their growth rates. Such a feedback loop can be generated by a reduction in body mass at high herbivore density, followed by a reduction in survival and reproduction. Despite the lasting deterioration of plant communities on Anticosti Island (Québec, Canada) following the introduction of a white-tailed deer population in absence of natural predation, the size of this population has remained high during the last decades. One of the mechanisms suggested to explain this situation is the use of sources of forage independent or temporally uncoupled from deer browsing pressure. Two types of forage used by deer on Anticosti Island are considered independent or temporally uncoupled from deer browsing, namely drifted seaweed and balsam fir. We determined how body mass of deer on Anticosti Island is influenced by sources of forage that are dependent, independent and temporally uncoupled from deer browsing. First, we demonstrated experimentally that deer density had a negative effect on the summer abundance of preferred forbs and shrubs, which in turn had a positive effect on body mass in the fall. Second, we demonstrated that the contribution of seaweed to diet outside winter was smaller than 23% and did not explain variations in body mass in the fall. Fall body mass rather increased with the contribution of plants from open habitat to diet. Third, we demonstrated that overwinter mass loss decreased with the use of balsam fir stands during a harsh winter. Our findings provide a better understanding of how overabundant herbivores can benefit from sources of forage influenced to varying degrees by browsing. The next step would be to determine the impact of these different resources on the growth rate of overabundant herbivore populations.
Marzouk, Anis. "Effet du choix alimentaire sur le comportement et les traits d'histoire de vie du gastéropode herbivore Littorina saxatilis". Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/25733.
Pełny tekst źródłaDiet is influenced by both food availability and the feeding preferences of consumers. In St. Lawrence maritime estuary, the herbivorous intertidal snail Littorina saxatilis feeds on two different functional groups of algae: chain-forming diatoms and filamentous green algae. In laboratory experiments, it strongly preferred diatoms, but when structural attributes of the algae were removed, this preference was weaker, suggesting that some aspect of feeding (e.g., ingestion) influences preferences. Densities of snails in the field were much higher on diatom-dominated habitats, consistent with preferences observed in the laboratory. Experiments in the field and laboratory found that diet also affected life history traits of snails with diatoms provided in monospecific or mixed diets increasing juvenile growth rates, but not fecundity. This study shows that this herbivore has dietary preferences and that a diet of its preferred food can positively affect certain life history characteristics.
Du, Zhen-Yu. "Consequences of fat feeding on growth and body lipids in a herbivorous fish (Grass carp, Ctenopharyngodon idella) : mechanisms related to fatty acid oxidation". Dijon, 2005. http://www.theses.fr/2005DIJOS019.
Pełny tekst źródłaGadéa, Alice. "Lichens et gastéropodes du Subantartique : écologie chimique et relations trophiques". Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1B041/document.
Pełny tekst źródłaLichen-lichenivore interactions are mediated by the presence of metabolites in lichens, which may impact lichenivore food preferences. In the environmental context of the Subantarctic, with a low animal and “plant” biodiversity, the surprising lichen flora contributed to the success of a the only endemic subantarctic land Gastropod, Notodiscus hookeri. To better understand the snail-lichen interactions, we analyzed the food preferences of this lichenivore snail and tried to pinpoint key lichen traits modulating the trophic interaction. From observations and samplings realized on Possession Island (Crozet Archipelago, Terres Australes et Antarctiques Françaises), two decisive stages of the interaction were studied: (i) the snail feeding behavior in situation of nutritional choice, (ii) its gustatory response when facing isolated metabolites in no-choice situations. Preferential grazing of some lichen parts was linked to both secondary and primary metabolites concentrations. Intrathalline localization of metabolites was performed in three lichen species consumed by the snail and widespread on Possession Island (Argopsis friesiana, Pseudocyphellaria crocata and Usnea taylorii), using chromatographic and spectrometric techniques (LC-DAD-MS, GC-MS, microdissection coupled to LC-DAD-MS, DART-MS) and imaging mass spectrometry ((MA)LDI-MS). N. hookeri appears to be a generalist and opportunistic gastropod, feeding on most lichen species encountered. However, it is able to discriminate between lichen parts, preferentially grazing on parts with the highest nutrient value, in spite of the presence of potential deterrent secondary metabolites. We described several mechanisms helping snails to overcome the toxicity of some lichen metabolites. Snail feeding choices result in trade-off between benefits of absorbing appetent metabolites of high nutritive value and the cost of physiological processes (detoxification, cleavage and excretion) caused by the ingestion of deterrent metabolites. To conclude, three main key parameters might be relevant in future to study the interactions between lichens and lichenivores. They correspond to the nature, the histolocalisation and the content of secondary metabolites balanced by the amount of nitrogen along with sugars and polyols. Imaging techniques have provided a new and promising way to visualize the heterogeneous distribution within the thallus between these metabolites. The ratios of appetent/non appetent compounds are likely to play a major role in food selection by this land snail
Vourc'h, Gwenaël. "Interactions entre plantes longévives et grands mammifères : défense chimique du thuya géant et herbivorie par le cerf-à-queue-noire en Colombie Britannique (Canada)". Montpellier 2, 2001. http://www.theses.fr/2001MON20189.
Pełny tekst źródłaMassé, Ariane. "Comportement d'approvisionnement et sélection de l'habitat d'un grand herbivore à haute densité et en absence de prédation : le cerf de Virginie à l'île d'Anticosti". Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/27892/27892.pdf.
Pełny tekst źródłaCampeau, Allen. "Remotely-sensed changes in the primary productivity of migratory caribou calving grounds and summer pasture : the mixed influences of climate change and caribou herbivory". Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27199.
Pełny tekst źródłaThis thesis used remote sensing to examine how changes in caribou abundance can impact forage availability, and how these changes might in turn affect the population dynamics and space use patterns of migratory caribou. We investigated these relationships for the Rivière-George caribou herd (RGH) and its calving grounds and summer range in Northern Quebec and Labrador (Canada) from 1991-2011. We modelled the relationships between primary productivity and various climatic variables, allowing us to isolate the effects of non-climatic factors, such as caribou herbivory, on primary productivity. We found a negative relationship between caribou density and primary productivity at the range-scale, suggesting that caribou herbivory can reduce forage abundance and contribute to habitat degradation. However, a strong warming trend over the study period, coupled with a decline in RGH population size, meant that we observed a trend towards higher primary productivity. This greening trend may represent vegetation recovery following the reduction in caribou herbivory and/or an effect of climate warming.
Paquette, Jesseca. "Tendances environnementales en Afrique de l’Est au Plio-Pléistocène : étude des isotopes stables de carbone et d’oxygène de l’émail des herbivores". Thèse, 2018. http://hdl.handle.net/1866/21909.
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