BIO 359K Lecture Notes - Lecture 12: Cooperative Breeding, Group Selection, Inclusive Fitness
Document Summary
Social behavior can be examined from a cost/benefit standpoint. Some costs and benefits are very obvious, but some are not. For instance, aerodynamic advantage is a benefit of birds flying in a v formation that is not necessarily obvious. Sociality evolves when net benefits of close associations >> costs. Dominance hierarchies and territories are two factors that can help reduce these costs for animals. Aerodynamic benefit: reduced cost of movement in pelicans. Birds in formation behind leader had a slower wingbeat frequency and lower heart rate, so large birds have reduced flight costs by flying in formation. Clearly, some of the costs associated with living in groups would be competition and disease. Competition (occurs when one individual negatively affects fitness of another; can increase with size of a group): can limit sociality and group size. There"s a positive correlation between competition for resources and group size. Remember that territoriality and dominance hierarchies can reduce the costs of sociality.
