An example of inbreeding in the wild is an isolated group of 40 adders in Sweden. Because they had no access to others of their species, the snakes' offspring interbred repeatedly. The champion race mare Coronation V is an example of inbreeding as the result of a breeder's artificial selection.
Inbreeding refers to the mating of close relatives. It happens in the wild when small populations of a species are cut off from others of their kind, as when farming activities isolated the Swedish adders. Another example is the gray wolves of Isle Royale, Michigan, who have been unable to interbreed with wolves from Canada due to lack of ice bridges between these populations for several years. In both cases, inbreeding has led to increased numbers of animals with deformities and lowered reproductive success. Because closely related animals are more likely to share lethal or detrimental recessive genes, mating these animals increases the risk that the offspring inherit a deleterious recessive gene from both parents.
In spite of the risks of inbreeding, human breeders sometimes mate related animals to produce a consistent type expressing desirable traits. In the case of Coronation V, her parents, a son and daughter of the French champion sire Tourbillon, were both excellent racehorses. Coronation V was the best French race mare of her time, but was completely barren as a broodmare.