Author:

Keywords:

worker reproduction, worker policing, inclusive fitness, kin selection, social insects, theoretical modelling, Science & Technology, Life Sciences & Biomedicine, Ecology, Evolutionary Biology, Genetics & Heredity, Environmental Sciences & Ecology, eusocial Hymenoptera, self-policing, social policing, tragedy of the commons, APIS-MELLIFERA-CAPENSIS, COLONY KIN STRUCTURE, HONEYBEES APIS, SOCIAL INSECTS, SEX-ALLOCATION, ANT WORKERS, EVOLUTION, HYMENOPTERA, CONFLICT, QUEEN, Altruism, Animals, Biological Evolution, Computer Simulation, Hymenoptera, Models, Biological, Reproduction, Social Dominance, 0602 Ecology, 0603 Evolutionary Biology, 0608 Zoology, 3103 Ecology, 3104 Evolutionary biology, 3109 Zoology

Abstract:

Insect societies are vulnerable to exploitation by workers who reproduce selfishly rather than help to rear the queen's offspring. In most species, however, only a small proportion of the workers reproduce. Here, we develop an evolutionarily stable strategy (ESS) model to investigate factors that could explain these observed low levels of reproductive exploitation. Two key factors are identified: relatedness and policing. Relatedness affects the ESS proportion of reproductive workers because laying workers generally work less, leading to greater inclusive fitness costs when within-colony relatedness is higher. The second key factor is policing. In many species, worker-laid eggs are selectively removed or ‘policed’ by other workers or the queen. We show that policing not only prevents the rearing of worker-laid eggs but can also make it unprofitable for workers to lay eggs in the first place. This can explain why almost no workers reproduce in species with efficient policing, such as honeybees, Apis, and the common wasp, Vespula vulgaris, despite relatively low relatedness caused by multiple mating of the mother queen. Although our analyses focus on social insects, the conclusion that both relatedness and policing can reduce the incentive for cheating applies to other biological systems as well.