Recherche avancée
Affichage des résultats 201 à 220 sur 8426 au total
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Titre à venir
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New insights into the genome dynamics of the bdelloid rotifer Adineta vaga and its DNA repair mechanisms
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The behavioral ecology of predators and dangerous prey
The study of predator-prey behavior is of primary importance to the field of ecology. However, few studies measure interactions between predators and their most dangerous prey. Our team used long-term datasets from Yellowstone National Park and Scandinavia to evaluate 1) the role of cooperative hunting in the ability of predators to hunt dangerous prey, 2) how predator preference for differentially dangerous prey species changes in relation to their relative abundance, and 3) how the kill rate of a top predator was affected by the presence of another. We found that 1) wolves (Canis lupus) were more cooperative when hunting bison (Bison bison), their most dangerous North American prey, than when hunting elk (Cervus elaphus). 2) Contrary to the prey switching hypothesis, wolves in northern Yellowstone attacked and killed disproportionately more of the rarer, but safer species; wolves maintained a strong preference against bison, even when this species was more than twice as abundant as elk. Analyses of wolf-bison behavioral interactions indicate that wolf preference against bison reflected an inability to consistently overcome bison antipredator defenses. 3) Finally, although brown bears (Ursus arctos) can monopolize wolf kills, we found no support in either Yellowstone or Scandinavia for the common assumption that brown bears cause wolves to kill more often. On the contrary, our results showed the opposite effect, suggesting that brown bear presence actually reduces wolf kill rate. One potential explanation for decreased wolf kill rate is the energetic costs associated with prematurely abandoning a kill to hunt dangerous prey. This research contributes to the current body of work addressing the effects of wolf reintroduction in Yellowstone, and sheds light on the behavioral relationships at play in a special type of predator-prey interaction: predators that hunt dangerous prey.
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Transcriptomic rewiring induced by domestication : a case study in tomato
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Adaptation of A-to-I RNA editing and the impact on genome evolution
Adenosine-to-inosine (A-to-I) editing is hypothesized to facilitate adaptive evolution by expanding proteomic diversity through an epigenetic approach. However, it is challenging to provide evidences to support this hypothesis at the whole editome level. In this study, we systematically characterized 2,114 A-to-I RNA editing sites in female and male brains of D. melanogaster, and nearly half of these sites had events evolutionarily conserved across Drosophila species. We detected strong signatures of positive selection on the nonsynonymous editing sites in Drosophila brains, and the beneficial editing sites were significantly enriched in genes related to chemical and electrical neurotransmission in Drosophila. By adopting a method originally designed to detect linkage disequilibrium of DNA mutations, we examined the editomes of ten metazoan species and detected extensive linkage of editing in Drosophila and cephalopods. The prevalent linkages of editing in these two clades, many of which are conserved between closely related species and might be associated with the adaptive proteomic recoding, are maintained by natural selection at the cost of genome evolution. Nevertheless, in worms and humans, we only detected modest proportions of linked editing events, the majority of which were not conserved. Furthermore, the linkage of editing in coding regions of worms and humans might be overall deleterious, which drives the evolution of DNA sites to escape promiscuous editing. Altogether, our results suggest that the linkage landscape of A-to-I editing has evolved during metazoan evolution. If time permitting, I will also talk about other work related to adaptive evolution at the post-transcriptional level.
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Prebiotic dynamics of compartmentalized replicators
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Développement pubertaire normal et pathologique chez l'enfant
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Découverte du fonctionnement et de l'évolution d'un virus multipartite, le Faba bean necrotic stunt virus
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Sequencing and applications using Oxford Nanopore long reads at Genoscope
Sequencing by nanopore is a promising technology that makes it possible to determine the sequence of a DNA fragment without amplification and without synthesizing a DNA strand. Available since 2014 the Oxford Nanopore sequencer, named MinION, is a portable device that enables the sequencing of complex genomes at low cost. Nowadays, the MinION can deliver several gigabases of data and is able to sequence DNA fragments up to 1Mb. The presentation will provide an overview of how the device has evolved over the last two years and what are the main applications today. Next we'll end up with the presentation of the PromethION, the high-throughput platform that promise to lower the cost of sequencing a human genome to <1000$.
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usociality through conflict dissolution via queen specialization
Queens strongly influence offspring social behaviors across the diverse eusocial taxa, suggesting that maternal influence might be involved in the origin of eusociality. Such ancestral maternal influence could have been manipulative or an honest signal, but a manipulative maternal influence could make eusociality unstable as offspring resistance evolves. Using an analytical model and individual based simulations, we show that an ancestral manipulative maternal influence becomes an honest signal under feasible conditions as maternal specialization into reproduction evolves. The reason is that specialization can move the population out of the zone of parent-offspring conflict over helping, a process that we term conflict dissolution. The key for this process is that helpers alleviate life-history trade-offs faced by mothers. Our results can simultaneously explain the origin of eusociality and its widespread association to a maternal influence via evolutionarily shifts of manipulation into honest signals.
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Following evolution after the horizontal transfer of synonymous versions of an antibiotic resistance gene.
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Transmission Biases & Cumulative Culture in Human and Nonhuman Primates
Cumulative culture requires individuals to build upon the knowledge of previous generations such that trait complexity/efficiency evolves across generations. Such cumulative cultural evolution is arguably unique to humans and is widely held to be responsible for our outstanding success in colonising virtually every terrestrial habitat on the planet and solving countless ecological, social and technological challenges. In contrast, social learning (learning from others) underlies the wide-spread occurrence of traditions or culture in all animals. Although social learning is a cheap and efficient form of learning, it is not adaptive to use social information indiscriminately due to its potential unreliability. Thus it is predicted that social learning strategies (heuristics / transmission biases) should evolve enabling individuals to avoid the costs associated with asocial learning and determine when they should use social information and from whom they should acquire it. I shall review several of my recent empirical studies, with young children and non-human primates, highlighting the role of socio-cognition, and in particular the potential role of transmission biases, in humanity's striking capacity for cumulative culture. (page web: https://www.dur.ac.uk/research/directory/staff/?id=5444)
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Meta-analysing the field of evolution, ecology, biology and beyond
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Reappraisal of metformin efficacy in the treatment of type 2 diabetes: a meta-analysis of randomised controlled trials.
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Does phenotypic plasticity facilitate or slow down evolution?
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The evolution of chromatin-associated proteins in Drosophila
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An evolutionary perspective on meiotic recombination in vertebrates
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The evolution of interdependency between symbiotic organisms by neutral evolution
Symbiosis evolution is often viewed as a progress, with emergence of new adaptive properties. However, symbiosis also enhances the interdependence between partners. I describe several such interdependences, and emphasize that they arise without emergence of new property. Generally, when two partners permanently interact, a mutation in one partner can be complemented by the other. Independency is then lost without any positive selection, in a neutral evolution. The accumulation of such steps makes the reversion to independency unlikely, and drives interdependency in symbiosis.
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Les cétacés ont-ils du nez ?
La perception chimique (olfaction et gustation) est impliquée dans de nombreuses fonctions biologiques chez les mammifères terrestres. Elle permet notamment de s'alimenter, de s'orienter, de réagir aux perturbations abiotiques et biotiques de l'environnement et de structurer et coordonner la vie sexuelle et sociale. Cependant, chez les mammifères marins et plus particulièrement chez les cétacés, ces modalités sensorielles ont été extrêmement peu étudiées au profit de la communication acoustique. Nous développons actuellement des travaux de recherches visant à caractériser les capacités olfactives et gustatives de ces animaux. Notre approche pluridisciplinaire intègre 3 niveaux d'exploration: 1) Un volet en écologie chimique dont l'objectif est d'analyser et identifier les molécules émises par les individus, susceptibles d'être informatives pour les congénères ; 2) Un volet neurobiologique permettant d'explorer les organes récepteurs, les structures cérébrales et les voies nerveuses impliquées dans la perception et l'intégration des signaux chimiques (prélèvements sur des spécimens échoués) ; 3) Un volet comportemental visant à étudier, en milieu naturel, les fonctions biologiques des informations chimiques, notamment dans le cadre de l'alimentation et dans la vie sociale de ces mammifères marins. Outre son aspect fondamental, notre projet pourrait permettre, à terme, d'identifier des molécules répulsives utilisables dans le cadre de la conservation, notamment en prévention contre les menaces anthropiques qui pèsent sur les cétacés, telles que les prises accessoires dans les filets de pêche ou les collisions avec les navires.
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Linking chromatin organization and transcriptional regulation during Drosophila embryogenesis
-you can find out more about Yad's work on developmental epigenomics from her group's website:http://igfl.ens-lyon.fr/equipes/y.ghavi-helm-developmental-epigenomics