1. Behavioral ecology is the study of the adaptive significance of behavior. Behavioral ecologists measure the adaptiveness of behavior by estimating fitness (reproductive success). Fitness can be estimated from the effect behavior has on survival, or some measure of reproduction such as the number of matings an individual has, the benefits and costs of the behavior, or the number of offspring produced.
2. Optimal foraging theory states that natural selection favors foraging behavior that maximizes the net energy gained from feeding on a given food item. However, this overall standard may be violated by animals in search of specific nutrients or attempting to avoid being eaten themselves.
3. A territory is an area which is used exclusively by one animal or social group and is actively defended against intrusion by others. Animals are territorial when the benefits of exclusive use of resources in a territory outweigh the costs of defense and risk of injury or predation.
4. Mate choice can be adaptive if individuals in a breeding population differ in the quality of their genes of resources they hold. The advantages of mate choice include selecting parasite-free individuals (a trait which may be heritable) or acquiring food or nest sites needed for reproduction. Trivers' observation was that parental investment would be the most important quality to look for in mate selection.
5. Sexual selection is the process by which individuals compete for access to mates; it involves competition among members of one sex for mates, and mate choice. Natural selection concerns the evolution of traits favoring survival; sexual selection concerns the evolution of traits that favor mating success.
6. Monogamy is a mating system in which a male and female form a pair bond during a breeding season. Polygyny occurs when a male mates with more than one female, and polyandry occurs when a female mates with more than one male. The more care the offspring require, the more likely the (bird) animals will pair monogamously.
7. Reciprocal altruism is when individuals perform an act of altruism in expectation that they will receive similar treatment from others. Altruistic behavior is that which is not in the individual's self-interest. Kin selection maximizes one's inclusive fitness if by sacrificing one's self for one's relatives his total gene contribution to the next generation increases. Inclusive fitness refers to the total number of one's genes that are passed on to the next generation. Kin selection can lead to altruistic behavior when the individuals in a society are related to one another.
8. An individual who sounds an alarm call is drawing attention, and therefore, usually danger, to him/herself. Females with relatives nearby tend to be the squirrels that give alarm calls, thereby protecting a large quantity of genetic material they share with their sisters and their offspring, even if the female herself is attacked.
9. Biological and cultural evolution have led to adaptive change in human evolution. Studying human behavior across several cultures can give indications of the relative contributions of these processes.