The emergence of a superorganism through intergroup competition

Abstract

Surveys of insect societies have revealed four key, recurring organizational trends: (i) The most elaborated cooperation occurs in groups of relatives. (ii) Cooperation is typically more elaborate in species with large colony sizes than in species with small colony sizes, the latter exhibiting greater internal reproductive conflict and lesser morphological and behavioral specialization. (iii) Within a species, per capita brood output typically declines as colony size increases. (iv). The ecological factors of resource patchiness and intergroup competition are associated with the most elaborated cooperation. Predictions of all four patterns emerge elegantly from a game-theoretic model in which within-group tug-of-wars are nested within a between-group tug-of-war. In this individual selection model, individuals are faced with the problem of how to partition their energy between investment in intercolony competition versus investment in intracolony competition, i.e., internal tugs-of-war over shares of the resources gained through intergroup competition. An individual's evolutionarily stable investment in between-group competition (i.e., within-group cooperation) versus within-group competition is shown to increase as within-group relatedness increases, to decrease as group size increases (for a fixed number of competing groups), to increase as the number of competing groups in a patch increases, and to decrease as between-group relatedness increases. Moreover, if increasing patch richness increases both the number of individuals within a group and the number of competing groups, greater overall cooperation within larger groups will be observed. The model presents a simple way of determining quantitatively how intergroup conflict will propel a society forward along a ''superorganism continuum.'' conflict ͉ cooperation ͉ group selection ͉ tug-of-war ͉ social insects

Altruism in insect societies and beyond: voluntary or enforced?

“…o Does coercion, by promoting more efficient societies, help these species in ecological, macro-evolutionary terms, such as in interspecies competition [75]? o Is coercion important in the evolution of eusociality [9,36,37] …”

Collective action problem in heterogeneous groups

“…It is also possible that individual shares are defined by outcomes of an additional within-group conflict. Such nested or multi-level contests have also been studied [118,123,[127][128][129][130] with a general conclusion that external conflicts cause increasing within-group cooperation and reduced free-riding.…”

Group Size and Social Conflict in Complex Societies

“…Most theoretical works modeling how social and ecological factors influence social conflict either are simple two-player models (Johnstone 2000;Shen and Reeve 2010;Cant 2012) or do not consider the effect of group size (Frank 1995;Foster 2004; but see Reeve and Hölldobler 2007, which modeled within-group conflict in the context of betweengroup competition). Thus, the general relationships among group size, group productivity, and social conflict remain largely unexplored theoretically, and given the mixed empirical evidence of a consistent relationship between group size and social conflict, better predictive models are clearly needed.…”