Abstracts (first author)
Social role specialisation promotes cooperation
Understanding the evolution of cooperation is crucial for understanding the evolution of breeding systems. An assumption implicit in almost all cooperation research is that cooperative behaviour in one specific ecological task evolves independently of other such tasks; however, this is often unlikely to be true. We use an individual-based simulation to relax this assumption, using biparental care as a model of cooperative behaviour. We show that synergistic costs of investing in two distinct care tasks, or a negligible sex-based asymmetry in their costs, select for sex-based task specialisation and stabilise cooperation between parents. Cooperation persists in spite of intense sexual selection and sex-biased mortality. Remarkably, with increased levels of cooperation, population size is also increased. We therefore show that ignoring the multivariate tasks animals face in nature leads to restrictive predictions of the ecological and demographic conditions under which biparental care in particular, and cooperation in general, are maintained.