Cooperation and competition within male lion coalitions

Male lions hold tenure over prides in coalitions, and this study used genetic and behavioural data to show how coalition size and kinship shape reproductive sharing. Small coalitions were composed of relatives that tolerated reproductive skew because non-breeders gained indirect fitness, whereas large coalitions contained unrelated males that joined only when each could expect direct reproduction. The analysis clarified how kin selection and mutualism jointly stabilise male alliances, explaining why companion choice depends on both relatedness and group size. It is a key reference for understanding the bargaining logic behind one of the most conspicuous cooperative systems in mammals.