Models of winner and loser effects: a cost–benefit analysis

Winner and loser effects, in which the probability of future success depends on individual’s interaction history, help shape the structure of social hierarchies in animal groups. While reports have documented that both magnitude and symmetry of these effects vary widely across different systems, questions remain whether these effects serve to reduce the associated costs during hierarchy formation. In a series of models, cost–benefit properties of an emerging hierarchy were assessed in relation to variation in winner and loser effects. Coupling high winner effects with low loser effects resulted in an overall increase in aggressiveness in the group, increasing the costs of hierarchy formation for the participants and disrupting its maintenance. In contrast, low winner and high loser effects resulted in an efficient cost reduction while also encouraging stability in social status.