Inbreeding leads to extinction by Richard Frankham and Katherine Ralls.
Do genetic problems contribute to the endangerment and extinction of wild populations? Conservation biologists initially thought that they would, and seriously so.
Theoretical work in the 1980s indicated that small populations in the wild suffer from increased extinction because of an unavoidable increase in matings between close relatives. Inbreeding reduces reproductive success in populations of naturally outbreeding species, both in captivity and in the wild, and it also increases extinction rates in laboratory populations of fruitflies and mice.
The Glanville fritillary butterfly studied by Saccheri et al. has a predictable yearly life cycle. Adults emerge, mate, and lay eggs in June. Because small population size results in both inbreeding and loss of genetic variation, the degree of genetic variation in a population serves as a measure of the extent to which it is inbred. Saccheri et al. determined the genotypes of female butterflies from 42 populations at eight variable genetic loci. Theoretical studies have shown that genetic factors probably contribute to
Ramskill 2 extinction's, even when demographic and environmental fluctuations and catastrophes are operating.
Frankham, Richard and Ralls, Katherine. "Inbreeding leads to extinction".
Nature, 2 April 1998: 441-2.