Pantheon SEMPARIS Le serveur des séminaires parisiens Paris

Statut Confirmé
Date Vendredi 13 Mai 2022
Heure 13:00
Institut LPENS
Salle Salle Favard (IBENS)
Nom de l'orateur De Monte
Prenom de l'orateur Silvia
Addresse email de l'orateur
Institution de l'orateur Institute de Biologie de l'Ecole Normale Superieure
Titre Aggregation and behavioural strategies in the 'social' amoeba Dictyostelium discoideum
Résumé The 'social' amoeba D. discoideum is facultatively multicellular. Starvation triggers a life cycle where single cells come together to form multicellular fruiting bodies, essential for efficient dispersal and long-term survival. In this process, part of the cells die while promoting the survival of the spores. The evolution of self-sacrificial behaviour is more easily understood when all cells in the body share the same genome. It is therefore puzzling to observe that in natural conditions multicellular aggregates tend to be genetic chimeras, so that genetic conflicts are unavailable. Theory predicts that the spread of genotypes that reap more than their fair share of benefits from the group -- the so-called cheaters -- should prevent cooperative behaviour to be evolutionary stable. We compared the social performance in chimeras composed of isogenic cells harvested at different phases of population growth, and found that social behavior is modulated by phenotipic plasticity as well as genetic background. By tracing the origin of spore biases to the process of aggregation from single cells, we explored the single-cell determinants of differences in social behaviour. Finally, we show that biases due to non-genetic sources of phenotypic variation are comparable to genetic effects, and can dominate over genetic differences, overturning classical definitions of social behaviour. Our observations suggest that inevitable heterogeneity in cell-level physical properties may act - by breaking heritability of social behaviour - as a hindrance to the evolutionary success of cheaters, and this even when social interactions within the multicellular body are neglected.
Numéro de preprint arXiv
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