Inbreeding, the mating of close kin, and outbreeding, the mating of distant relatives or unrelated organisms, have long been important subjects to evolutionary biologists. Inbreeding reduces genetic diversity in a population, increasing the likelihood that genetic defects will become widespread and deprive a population of the diversity it may need to cope with its environment. Most plants and animals have evolved behavioral and morphological mechanisms to avoid inbreeding. However, today many endangered species exist only in small, very isolated populations where inbreeding is...