Karen J. Prager, Ph.D., A.B.P.P.
Professor of Psychology and Program Head for Gender Studies
Diplomate in Family Psychology
The University of Texas at Dallas
More Information About Dr. Prager's work
Two processes by which evolutionary change occurs
Natural selection:Species compete for resources in order to survive. Individual differences in inherited characteristics either contribute to or detract from efforts to survive. Members of species with advantageous inherited characteristics are more likely to survive long enough to reproduce their genes. Thus, advantageous genes are those most likely to stay in the gene pool (as opposed to dying out).
Sexual selection:Two processes.
(1) Intrasexual selection occurs when members of one sex compete for the opportunity to mate (with a member of the other sex). Individual differences in inherited characteristics can either contribute or detract from efforts to win the competition. Members of species with advantageous inherited characteristics are more likely to win the competition, mate, and perpetuate their genes in offspring.
(2) Epigamic selection occurs when members of one sex prefer mating with members of the other sex on the basis of individual differences in inherited characteristics (e.g., bright feathers, large antlers). If one sex selects mating partners on the basis of particular features, then those features will be more characteristic of one sex than the other.