Showing results 801 to 820 on 1341 in total
Thèse de Henri PUSA le lundi 4 février 2019 à 13 h, salle de conférences BU (La Doua)
Thèse de Frédérique Billy - mercredi 9 décembre - 14h00- Salle des thèses - Faculté de Médecine Laennec
These de Gustavo Olivera - Vendredi 18 février 2011 - 14h00 - Salle des thèses (Faculté Laennec)
Thèse Michael PHILIPPE le vendredi 15 décembre 2017 à 14 h, médiathèque Paul Zech (Faculté de pharmacie Lyon)
These d'Arnaud Poret - Mercredi 1er juillet 2015 - 14h00 - Salle des Conférences de la Médiathèque Paul Zech - Faculté de Médecine Lyon Est
Thèse de Alice Julien-Laferrière le jeudi 8 décembre 2016 à 14 h - salle Fontannes, bâtiment Darwin D (La Doua)
Competition between organisms influences the processes governing the colonization of new habitats. As a consequence, species or populations arriving first at a suitable location may prevent secondary colonization. While adaptation to environmental variables (e.g., temperature, altitude, etc.) is essential, the presence or absence of certain species at a particular location often depends on whether or not competing species co-occur. For example, competition is thought to play an important role in structuring mammalian communities assembly. It can also explain spatial patterns of low genetic diversity following rapid colonization events or the ``progression rule'' displayed by phylogenies of species found on archipelagos. Despite the potential of competition to maintain populations in isolation, past quantitative analyses have largely ignored it because of the difficulty in designing adequate methods for assessing its impact. We present here a new model that integrates competition and dispersal into a Bayesian phylogeographic framework. Extensive simulations and analysis of real data show that our approach clearly outperforms the traditional Mantel test for detecting correlation between genetic and geographic distances. But most importantly, we demonstrate that competition can be detected with high sensitivity and specificity from the phylogenetic analysis of genetic variation in space.Joint work with L. Ranjard, D. Welch and M. Paturel.
Thèse de Vicente Acuna - vendredi 4 juin 2010 - 14h00 - Amphithéâtre du CNRS
Thèse de Thibault Gayet, le vendredi 13 juillet 2018 à 13 h 30, salle de conférence BU (Doua)
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Systematics is the study of characters distribution and evolution among species. Recent advances in molecular biology and genomics provide systematists with a tremendous amount of characters never previously attained by morphology alone. Despite its limitations, I argue here that morphology would continue to be fundamental to the systematic practice and that the genomic revolution would result in a renaissance in the conceptualization and homologization of morphological data. I will mainly focus on two taxonomic programs, namely DNA barcoding and phylogeny inference, and try to place morphological systematics within the broader frame of the Extended Evolutionary Synthesis.
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Animal conflict is usually seen as static, where each competitor has a definite underlying quality (i.e. condition, good genes) that determines its signal level. However, although many morphological signals are fixed during early development, some signals remain flexible through life (e.g. vocalisation, most behavioural traits). The level of signals of an individual can thus often fluctuate to avoid interferences, to adapt to both the presence of an audience or the resource holding potential and motivation of opponents. These fluctuations raise the question of how individuals decide at each moment their level of investment in signalling to claim a resource. Animals are indeed expected to constantly modulate their investment in a contest according to the payoff. Because of the inherent difficulty to study the temporal dynamics of communication between several individuals, how animals decide to enter or leave the contest and to what level invest in signalling has received mainly theoretical developments. Using the barn owl (Tyto alba) as a model species, I will present recent advances in the understanding of the role of cognition (individual recognition, memory) and social interactions in the dynamics of a communication process.
Mathematical and computational approaches based on network theory and complex system dynamics are increasingly showing their potential to address open problems on the spreading of communicable diseases on a spatially structured and heterogeneous human population. I will review my recent research work in this direction presenting studies on both fundamental problems and specific epidemic events. On the theoretical side, I will show how the mathematical formalism of reaction-diffusion processes and metapopulation networks can shed light on the impact of the complex features characterising individuals' mobility patterns on the propagation of emerging infections. How do traveling flows, journey duration and difference in travel frequency impact local mixing and transmission of influenza-like diseases? How do the mobility of individuals and their distribution in space determine dominance/co-dominance regimes in case of multiple interacting strains of the same pathogen? Besides these fundamental research questions, the same formalism can form the basis of data-driven computational models for the spatial spreading of real infection events. In case of an epidemic emergency, such models represent valuable tools for estimating in real time the transmission potential of the disease, providing assessment of the epidemic situation and projections of possible unfolding scenarios. I will discuss the two paradigmatic examples of the 2009 H1N1 pandemic and of the MERS-CoV outbreak.