Polymorphic mating systems are physical characteristics and other mating strategies one sex of a species, usually the male, develops to increase chances of mating.
An ESS is the behavioral strategy that provided higher fitness to individuals and became dominant over other strategies over the course of evolution.
It is the study of cooperative and competitive interactions between individuals with mathematical models. Game theory helps estimate costs and benefits associated with a strategy against others.
Hawk-dove game is a popular example used to illustrate the principles of ESS and practice application of game theory. One player acts as a hawk (competitive) or a dove (cooperative). Playing this game allows comparison of the success of these two strategies for obtaining resources.
Altruism is the reduction in an organism’s immediate fitness in order to benefit another’s.