Zoology 10th Edition by Stephen Miller,John Harley

Exercise 16

Evolution occurs because allelic frequencies change in populations. Allelic frequencies change as a result of chance events occurring in small populations, the migration of individuals into or out of a population, mutation, and natural selection. Directional selection is selection against one phenotypic extreme in a population. Disruptive selection is selection against the most common phenotype, and stabilizing selection is selection against both phenotypic extremes in a phenotypic range.
Conservation biologists attempt to preserve genetic diversity within populations. Which of the four evolutionary mechanisms described in this section has/have the potential to increase genetic diversity of populations? What does this say about the challenge faced by conservation biologists?