1. Chapter 51 Social behavior

2. Agonistic behavior Ritualized contest that determines which competitor gains access to a resource, such as food or mates. It involves threats or actual combat. The outcome of such contests may be determined by strength, size, or the effective use of horns, teeth, etc. It is most common in members of the same species.

3. Agonistic behavior It often involves symbolic conflict and often does not cause serious harm to either the winner or loser in the encounter. It may be used to establish and defend territories. It may be used to establish dominance hierarchies. Example: Male eastern grey kangaroos often “Box”

4. Altruism On occasion, some animals behave in ways that reduce their individual fitness but increase the fitness of other individuals in the population. Example: a squirrel that sees a predator approach often gives a high-pitched alarm call that alerts unaware individuals to retreat to their burrows.

5. Altruism An explanation can be seen in honeybees, where worker females share 75% of the same genes. When a worker honeybee stings an intruder while defending a hive, the worker sacrifices itself for its relatives, individuals who carry most of the same genes as that particular worker. The individual dies, but relatives survive to pass on their genes, including the gene for altruistic behavior. This concept is known as kin selection or inclusive fitness.