Animals living in groups must compete with one another for food, mates, and breeding areas.
Individuals waste energy for fighting or threatening one another.
Individuals waste time and energy by searching for food in the same places. Groups of animals transmit diseases to one another and attract predators. Agonistic Behavior Agonistic behavior includes all the aspects of competitive behavior within a species, including aggression, aggressive displays, appeasement, and retreat. When such behavior patterns are influenced by genes natural selection can operate. Natural selection increases the frequency of those behavioral types that reproduce most successfully.