Affichage des résultats 181 à 200 sur 7659 au total
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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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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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.
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.
-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
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- Évaluation et Modélisation des Effets Thérapeutiques - Bioinformatique, Phylogénie et Génomique Évolutive
Understanding how groups of species diversified, and how species phenotypes evolved during evolutionary history, is key to our understanding of patterns of biodiversity as we see them around us today. Phylogenetic comparative methods have highlighted that macroevolutionary rates (i.e. rates of diversification and phenotypic evolution) are strikingly heterogeneous in time and across lineages. However, describing and quantifying this heterogeneity, as well as understanding its drivers, remain challenging. I will present recent developments that allow a better consideration of smooth changes in diversification rates when estimating branch-specific rates across phylogenetic trees. I will also present models that allow better understanding and testing the effect of past environmental changes and interspecific interactions on diversification and phenotypic evolution. Empirical applications demonstrate the preponderance of many small (versus few important) diversification rate shifts in clades' evolution and the pervasive effect of past environmental changes on evolutionary rates across diverse clades spanning macro and microorganims.
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