Evolution, Ecology and Behavior - Video Stephen C. Stearns

Breeding strategies differ both among males and females of the same species as well as among different species. The difference in breeding strategies among members of the same species can usually be linked to frequency dependence. If the species is at evolutionary equilibrium, the relative fitnesses of these different strategies will be identical. Differing strategies have been found at the level of the gamete as well as at the level of different organisms and species.

Originally, altruism and self-sacrifice were thought to be incompatible with natural selection, even by Darwin. Now we have several explanations for how altruism can increase an individual's fitness. One is kin selection, or the idea that helping relatives can help increase one's genes in the population. Another involves ecological constraints and punishments. Here, individuals contribute to the group and wait their turn to reproduce.

Mating systems and parental care vary tremendously from species to species. Every species differs in how it protects its young from predators and provides its young with food, if it does so at all. The physical environment as well as behavioral dynamics in intra-species relationships all influence parental care. Often the mating system, which sex is dominant in mating, and whether fertilization is external or internal will determine much of the process of parental care.

The economic concept of game theory can be readily applied to evolution and behavior. By analyzing encounters between organisms as a mathematical "game," important information such as fitness payoffs and the proportions of "strategies" played by each group within a population can be inferred. While oftentimes these games are too simplified to apply directly to actual examples in nature, they are still useful models that help to convey important concepts.

There are several ways to examine the behaviors of organisms when they forage or hunt for food or mates. These behaviors become more complex in higher organisms, such as primates and whales, which can hunt in groups. Foragers and hunters have been shown to examine the marginal cost and marginal benefit of continuing an action and then adjust their behaviors accordingly. They are also able to handle risk by hoarding resources.

One can look at biodiversity from several perspectives. An ecological point of view tries to determine how necessary diversity is for an ecosystem to function. An economic point of view tries to capture the value of the "services" nature provides for mankind. An evolutionary point of view shows how artificial the human "right" to dominance is. Finally, a personal point of view captures the emotional basis for the values that humanity place on biodiversity.