On Predation, Competition, and the Advantages of Group Living
Many evolutionary reasons have been suggested as to why animals live in groups. Based on the costs and benefits associated with group living it appears that the risk of predation and the competitively induced need to forage efficiently are the most important forces responsible for the formation and maintenance of groups.
Most field studies and mathematical models that have investigated the environmental conditions that favor the formation of groups have studied the effects of either predation or competition. After examining some of these studies and their major conclusions, I present a model, based on the theory of games, that focuses on the combined action of predation and competition. Simulations under a variety of environmental conditions reveal that individuals that are poor competitors are more likely to remain in groups when the visibility of the habitat is low, when the level of competitive inequality among group members is low, when the carrying capacity of the habitat is high, and when the presence of neighbors enhances an individual’s feeding success.
Models, such as this one, that incorporate the effects of predation and resource competition, while accounting for how differences in age, sex, size, and past experience influence competitive ability, provide insights into the dynamics of social behavior. When other factors, such as kinship relationships and subtle interspecific interactions, are also considered, a general and predictive theory of social organization can be developed.
KeywordsInclusive Fitness Evolutionary Stable Strategy Group Living Prey Animal Feeding Success
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