Public goods dilemma in asexual ant societies

Abstract

Cooperation in biological, social, and economic groups is underpinned by public goods that are generated by group members at some personal cost. Theory predicts that public goods will be exploited by cheaters who benefit from the goods by not paying for them, thereby leading to the collapse of cooperation. This situation, described as the "public goods dilemma" in game theory, makes the ubiquity of cooperation a major evolutionary puzzle. Despite this generalization, the demonstration of genetic background and fitness effects of the public goods dilemma has been limited to interactions between viruses and between cells, and thus its relevance at higher levels of organismal complexity is still largely unexplored. Here we provide experimental evidence for the public goods dilemma in a social insect, the ant Pristomyrmex punctatus. In this species, all workers are involved in both asexual reproduction and cooperative tasks. Genetic cheaters infiltrate field colonies, reproducing more than the workers but shunning cooperative tasks. In laboratory experiments, cheaters outcompeted coexisting workers in both survival and reproduction, although a group composed only of cheaters failed to produce offspring. The operations of the public goods dilemma in P. punctatus showed a remarkable convergence with those in microbial societies, not only in fitness consequences but also in behavioral mechanisms. Our study reinforces the evolutionary impact of cheaters on diverse cooperative systems in the laboratory and in the field. social evolution | public goods game | social parasitism | self-organization | phenotypic plasticity

Epistasis between adults and larvae underlies caste fate and fitness in a clonal ant

“…HRIs usually do not forage and contribute little to cooperative tasks, and colonies with higher proportions of HRIs might therefore be less efficient at raising offspring. This interpretation is in line with findings in the thelytokous ant Pristomyrmex punctatus, in which colonies with a higher proportion of 'cheaters', which behave similar to C. biroi HRIs in that they reproduce more but don't contribute to cooperative tasks, have lower fitness 39 .…”

“…Individuals of this cheater lineage, which like C. biroi HRIs do not forage, have more ovarioles and lay more eggs than average individuals [29][30][31]50 . As mentioned above, a recent study showed that, in mixed colonies, the P. punctatus cheater lineage performs better than host workers, both in terms of survival and reproduction, while its fitness in isolation is greatly reduced 39 . The P. punctatus cheater lineage is an obligate social parasite, that is, it has lost the phenotypic plasticity that would allow it to function in isolation.…”

Stalk size and altruism investment within and among populations of the social amoeba

“…Theory and experimental evidence indicates that an optimal division of labour for the group can be undermined by the selfishness of individuals (Dobata & Tsuji, ). In eusocial insects, for example, workers behave selfishly by laying unfertilized eggs that develop into males (Visscher, ; Foster & Ratnieks, ; Halling et al ., ), actions that are deleterious to the group because they divert time and energy away from raising the offspring of the queen (Cole, ; Hammond & Keller, ).…”

Cheating and punishment in cooperative animal societies

“…But as cheating becomes more common, the benefits of cooperating (and hence, the benefits of associating with the group) diminish, and more cooperative groups outcompete groups with more free-riders (e.g. [21]). Thus, the solution to the game is a stable equilibrium frequency of each tactic, potentially explaining how variation in cooperative behaviour is maintained in natural populations.…”