Inbreeding avoidance behaviors

Inbreeding is defined as mating between individuals related by common ancestry. Thus, the degree to which a particular mating is inbred depends on how far back in a pedigree one begins counting common ancestors. In general practice, the term inbreeding is used to describe mating between close relatives (first cousins or closer). Animal breeders have known for centuries that inbreeding causes a loss of constitutional vigor and fertility in domestic livestock. A growing literature now demonstrates that the offspring of matings between close relatives in species of undomesticated birds and mammals are less fit than outbred offspring. The deleterious consequences of inbreeding suggest the possibility that many species have evolved behaviors that lower the frequency of inbreeding.