It has been suggested that this article or section be merged into inbreeding. (Discuss)

Inbreeding depression is reduced fitness in a given population as a result of breeding of related individuals. Breeding between closely related individuals results in more recessive deleterious traits manifesting themselves. The more closely related the breeding pair is, the more homozygous deleterious genes the offspring may have, resulting in very unfit individuals. In general, populations with more genetic variation do not suffer from inbreeding depression. Inbreeding depression is often the result of a population bottleneck. The phenomenon of inbreeding depression may occur in either plant or animal species. Wikipedia does not have an article with this exact name. ... Inbreeding is breeding between close relatives, whether plant or animal. ... Fitness (often denoted in population genetics models) is a central concept in evolutionary theory. ... In genetics, the term recessive gene refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele). ... Homozygote cells are diploid or polyploid and have the same alleles at a locus (position) on homologous chromosomes. ... For a non-technical introduction to the topic, see Introduction to Genetics. ... Inbreeding is breeding between close relatives, whether plant or animal. ... A population bottleneck (or genetic bottleneck) is an evolutionary event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing, and the population is reduced by 50% or more, often by several orders of magnitude. ... Divisions Green algae Chlorophyta Charophyta Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta—liverworts Anthocerotophyta—hornworts Bryophyta—mosses Vascular plants (tracheophytes) †Rhyniophyta—rhyniophytes †Zosterophyllophyta—zosterophylls Lycopodiophyta—clubmosses †Trimerophytophyta—trimerophytes Pteridophyta—ferns and horsetails Seed plants (spermatophytes) †Pteridospermatophyta—seed ferns Pinophyta—conifers Cycadophyta—cycads Ginkgophyta—ginkgo Gnetophyta—gnetae Magnoliophyta—flowering plants... Animalia redirects here. ...

Inbreeding depression and natural selection

Natural selection cannot effectively remove all deleterious recessive genes from a population for several reasons. First, deleterious genes arise constantly through mutation within a population. Second, in a population where inbreeding occurs frequently, most offspring will have some deleterious traits, so few will be more fit for survival than the others. It should be noted, though, that different deleterious traits are extremely unlikely to equally affect reproduction. An especially disadvantageous recessive trait expressed in a homozygous recessive individual is likely to eliminate itself, naturally limiting the expression of its phenotype. Third, recessive deleterious alleles will be "masked" by heterozygosity, and so heterozygotes will not be selected against (assuming dominance). Darwins illustrations of beak variation in the finches of the Galápagos Islands, which hold 13 closely related species that differ most markedly in the shape of their beaks. ...

Example of inbred depression

Image File history File links Shetland_pony_inbred. ... Image File history File links Shetland_pony_inbred. ...

Managing inbreeding depression

Introducing new genes from a different population can reverse inbreeding depression. Different populations have different deleterious traits, and therefore will not result in homozygosity in most loci in the offspring. This is known as Outbreeding Enhancement, practiced by conservation managers and zoo captive breeders to prevent homozygosity. However, intermixing two different populations may give rise to unfit polygenic traits in outbreeding depression It has been suggested that this article be split into multiple articles accessible from a disambiguation page. ... Short and long arms Chromosome. ... Heterosis is a term used in genetics and selective breeding. ... Outbreeding depression This phenomenon can occur in two ways. ...

Example species subject to inbreeding depression

• Chillingham Cattle
• Piperia yadonii
• Residents of Vlotho, Germany

Chillingham Cattle is the name of a herd of wild bovids at Chillingham Castle, Northumberland, England; also known as Chillingham Wild Cattle, this rare species herd of 62 animals (as of the year 2006) inhabits a very large woodland that has existed since the Middle Ages, although there were fewer... Piperia yadonii, also known as Yadon’s Piperia, is an endangered perennial herb, endemic to a narrow range of coastal habitat in northern Monterey County, California. ...

Example species not subject to significant inbreeding depression

despite extremely low effective population sizes The effective population size (Ne) is defined as the number of breeding individuals in an idealized population that would show the same amount of dispersion of allele frequencies under random genetic drift or the same amount of inbreeding as the population under consideration (Sewall Wright). ...

• Chatham Islands Robin
• Laysan Duck
• Mauritius Kestrel
• Toromiro^{[verification needed]}

Binomial name Petroica traversi (Buller, 1872) The Black Robin or Chatham Island Robin Petroica traversi is an endangered bird from the Chatham Islands off the east coast of New Zealand. ... Binomial name Anas laysanensis Rothschild, 1892 The Laysan Duck, Anas laysanensis, is a dabbling duck which is endemic to Laysan Island, Hawaii. ... Binomial name Falco punctatus Temminck, 1821 The Mauritius Kestrel (Falco punctatus) is a bird of prey from the family Falconidae endemic to Mauritius. ... Binomial name Sophora toromiro Toromiro (Sophora toromiro) is a species of tree formerly a common in the forests of Easter Island. ...

See also

• Hybrid vigour
• Population genetics

Heterosis is increased strength of different characteristics in hybrids; the possibility to obtain a better individual by combining the virtues of its parents. ... Population genetics is the study of the distribution of and change in allele frequencies under the influence of the four evolutionary forces: natural selection, genetic drift, mutation, and migration. ...

References

• Genetic Effects of Straying of Non-Native Hatchery Fish into Natural Populations