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Showing results 701 to 720 on 1456 in total
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Retraite du LBBE / LBBE retreat
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Tobias Baril (Université de Neuchâtel)
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Sensibilisation à l'identification des violences sexistes et sexuelles au travail
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Soutenance d'HDR Etienne Rajon
Emergence et évolution du métabolisme
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Modelling microbial evolution: from ecological interactions to developmental programs
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Rapid evolution of robustness following colonization of a new environment
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Soutenance de thèse de Jessica Cachelou
Vers une meilleure compréhension de la démographie des populations naturelles : le sanglier comme cas d’étude
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Soutenance d'HDR Damien de Vienne
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Decoding the Secrets of Asexual Evolution and Extreme Survival in bdelloid rotifer Adineta vaga
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Soutenance d'HDR Matthieu Boulesteix
Les éléments transposables dans les populations en expansion : dynamique et contribution à l’adaptation
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The identity of ecosystems: an evolutionary approach
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Can we do more with less ? Qualitative discrete-event models of ecological systems and their formal analysis
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Soutenance HDR Laure Ségurel
How are species adapting to their environment: Positive selection, balancing selection, and gut microbiota
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Retraite du laboratoire / Lab retreat
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Host phylogeny and diet drive the structure of mammalian microbial communities at different phylogenetic scales
Bacterial communities (microbiota) living in Mammal guts are composed of thousands of bacterial species that are essential for host physiology, immunity and diet. It has been shown that host phylogeny (genetics and immune system of the host) and diet are the two major factors driving the composition of gut microbiota. However, major questions remain: (i) the relative contribution of host phylogeny and diet at short and long time scales is highly debated and the two processes are not well characterized, (ii) host phylogeny may drive the composition through co-evolution with bacterial lineages or through niche selection, with closely-related hosts retaining similar bacteria from the environment. Here, we show that host phylogeny and diet are for the most part independent processes and do not drive the bacterial composition at the same taxonomic scale. Diet determines what lineage is present or not at deep bacterial phylogenetic levels through gain or loss of lineages creating nested communities. Host phylogeny, however, selects the lineages at finer scales through true turnover of lineages, consistent with a more stringent selection of tolerated antigens. Finally, it appears that co-speciation between hosts and bacterial lineages plays a minor role in driving the correlation between community composition and host phylogeny, suggesting that environmental filtering by host genetics is the dominant process at selecting bacterial lineages. Our results shed light on the long-timescale evolutionary dynamic of gut bacterial communities, which are multi-layered phylogenetic structures shaped very differently by host phylogeny and diet.
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Gathering, updating, and calibrating phylogenies for The Open Tree of Life
The Open Tree of Life project is a collaborative effort to synthesize, share, and update a comprehensive phylogeny of all 2.3 million named species. We have completed a draft synthesis of a single tree from hundreds of phylogenetic estimates using taxonomy as a scaffold. This synthesis is not static but rather will be continually revised as new data become available. This undertaking requires development of both novel infrastructure and analysis tools. I will discuss three components of this project: Phylesystem, an open database and web application for community curation of phylogenies using a git-based datastore, PhyScraper, a pipeline to continually update phylogenetic estimates as new data is generated, and FastDate, an algorithm to rapidly generate maximum a posteriori estimates of time-calibrated trees, even for phylogenies with hundreds or thousands of tips. Together, these developments reduce impediments to accessing, analyzing and reusing the phylogenetic information which is essential to biological research today.
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Transitions between combined and separate sexes in plants
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