title: The evolution of adhesiveness as a social adaptation.
abstract: Cellular adhesion is a key ingredient to sustain collective functions of microbial aggregates. Here, we investigate the evolutionary origins of adhesion and the emergence of groups of genealogically unrelated cells with a game-theoretical model. The considered adhesiveness trait is costly, continuous and affects both group formation and group-derived benefits. The formalism of adaptive dynamics reveals two evolutionary stable strategies, at each extreme on the axis of adhesiveness. We show that cohesive groups can evolve by small mutational steps, provided the population is already endowed with a minimum adhesiveness level. Assortment between more adhesive types, and in particular differential propensities to leave a fraction of individuals ungrouped at the end of the aggregation process, can compensate for the cost of increased adhesiveness. We also discuss the change in the social nature of more adhesive mutations along evolutionary trajectories, and find that altruism arises before directly beneficial behavior, despite being the most challenging form of cooperation.
authors.affiliation: Institut d'écologie et des sciences de l'environnement, Université Pierre et Marie Curie, Paris, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Garcia
authors.affiliation: Institut de Biologie de l'École Normale Supérieure, École Normale Supérieure, PSL Research University, Paris, France.
authors.forename: Guilhem
authors.identifier: http://orcid.org/0000-0003-3720-9089
authors.initials: G
authors.lastname: Doulcier
authors.affiliation: Institut de Biologie de l'École Normale Supérieure, École Normale Supérieure, PSL Research University, Paris, France.
authors.forename: Silvia
authors.initials: S
authors.lastname: De Monte
mesh_terms: D000268:Adhesiveness; D005075:Biological Evolution; D002448:Cell Adhesion; D008954:Models, Biological
keywords: adaptive dynamics; altruism; computational biology; evolutionary biology; genomics; microbial adhesion; none; social evolution; systems biology