Changes

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*[http://en.wikipedia.org/wiki/19th_century 1842]

*[https://en.wikipedia.org/wiki/19th_century 1842]

==Definitions==

==Definitions==

*1:  the interbreeding of closely related [[individuals]] especially to preserve and fix desirable characters of and to eliminate unfavorable characters from a stock

*1:  the interbreeding of closely related [[individuals]] especially to preserve and fix desirable characters of and to eliminate unfavorable characters from a stock

*2:  confinement to a narrow range or a local or limited field of [[choice]]  

*2:  confinement to a narrow range or a local or limited field of [[choice]]  

==Description==

==Description==

'''Inbreeding''' is [[reproduction]] from the [[mating]] of pairs who are closely related genetically. Inbreeding results in [http://en.wikipedia.org/wiki/Homozygous homozygosity], which can increase the [[chances]] of offspring being affected by [http://en.wikipedia.org/wiki/Recessive_trait recessive] or deleterious traits. This generally leads to a decreased fitness of a [[population]], which is called [http://en.wikipedia.org/wiki/Inbreeding_depression inbreeding depression]. An individual who results from inbreeding is referred to as ''inbred''. The avoidance of expression of deleterious recessive [http://en.wikipedia.org/wiki/Allele alleles] caused by inbreeding is thought to be the main selective force maintaining the outcrossing aspect of sexual reproduction.

'''Inbreeding''' is [[reproduction]] from the [[mating]] of pairs who are closely related genetically. Inbreeding results in [https://en.wikipedia.org/wiki/Homozygous homozygosity], which can increase the [[chances]] of offspring being affected by [https://en.wikipedia.org/wiki/Recessive_trait recessive] or deleterious traits. This generally leads to a decreased fitness of a [[population]], which is called [https://en.wikipedia.org/wiki/Inbreeding_depression inbreeding depression]. An individual who results from inbreeding is referred to as ''inbred''. The avoidance of expression of deleterious recessive [https://en.wikipedia.org/wiki/Allele alleles] caused by inbreeding is thought to be the main selective force maintaining the outcrossing aspect of sexual reproduction.

Livestock breeders often practice [[controlled]] breeding to eliminate undesirable characteristics within a [[population]], which is also coupled with culling of what is considered unfit offspring, especially when trying to establish a new and desirable [[trait]] in the stock.

Livestock breeders often practice [[controlled]] breeding to eliminate undesirable characteristics within a [[population]], which is also coupled with culling of what is considered unfit offspring, especially when trying to establish a new and desirable [[trait]] in the stock.

In [[plant]] breeding, inbred lines are used as stocks for the creation of [[hybrid]] lines to make use of the effects of [http://en.wikipedia.org/wiki/Heterosis heterosis]. Inbreeding in plants also occurs naturally in the form of [http://en.wikipedia.org/wiki/Self-pollination self-pollination].

In [[plant]] breeding, inbred lines are used as stocks for the creation of [[hybrid]] lines to make use of the effects of [https://en.wikipedia.org/wiki/Heterosis heterosis]. Inbreeding in plants also occurs naturally in the form of [https://en.wikipedia.org/wiki/Self-pollination self-pollination].

Inbreeding may result in a far higher phenotypic expression of deleterious [http://en.wikipedia.org/wiki/Dominance_relationship recessive genes] within a population than would normally be [[expected]]. As a result, first-generation inbred [[individuals]] are more likely to show physical and health [[defects]], including:

Inbreeding may result in a far higher phenotypic expression of deleterious [https://en.wikipedia.org/wiki/Dominance_relationship recessive genes] within a population than would normally be [[expected]]. As a result, first-generation inbred [[individuals]] are more likely to show physical and health [[defects]], including:

*Reduced [[fertility]] both in litter size and sperm viability

*Reduced [[fertility]] both in litter size and sperm viability

Inbreeding can occur just because a small [[population]] has been isolated during some time, so that all breeding individuals became genetically related. It can also occur in a large population if [[individuals]] tend to mate their relatives, instead of mating at [[random]].

Inbreeding can occur just because a small [[population]] has been isolated during some time, so that all breeding individuals became genetically related. It can also occur in a large population if [[individuals]] tend to mate their relatives, instead of mating at [[random]].

Many individuals in the first [[generation]] of inbreeding will never live to reproduce. Over time, with [[isolation]] such as a [http://en.wikipedia.org/wiki/Population_bottleneck population bottleneck] caused by purposeful ([http://en.wikipedia.org/wiki/Assortative_mating assortative]) breeding or natural environmental factors, the deleterious inherited traits are culled.

Many individuals in the first [[generation]] of inbreeding will never live to reproduce. Over time, with [[isolation]] such as a [https://en.wikipedia.org/wiki/Population_bottleneck population bottleneck] caused by purposeful ([https://en.wikipedia.org/wiki/Assortative_mating assortative]) breeding or natural environmental factors, the deleterious inherited traits are culled.

Island species are often very inbred, as their isolation from the larger group on a mainland allows natural selection to work upon their [[population]]. This type of [[isolation]] may result in the formation of [[race]] or even [http://en.wikipedia.org/wiki/Speciation speciation], as the inbreeding first removes many deleterious genes, and allows expression of genes that allow a population to adapt to an [[ecosystem]]. As the [[adaptation]] becomes more pronounced the new species or race radiates from its entrance into the new space, or dies out if it cannot [[adapt]] and, most importantly, [[reproduce]].

Island species are often very inbred, as their isolation from the larger group on a mainland allows natural selection to work upon their [[population]]. This type of [[isolation]] may result in the formation of [[race]] or even [https://en.wikipedia.org/wiki/Speciation speciation], as the inbreeding first removes many deleterious genes, and allows expression of genes that allow a population to adapt to an [[ecosystem]]. As the [[adaptation]] becomes more pronounced the new species or race radiates from its entrance into the new space, or dies out if it cannot [[adapt]] and, most importantly, [[reproduce]].

The reduced genetic [[diversity]] that results from inbreeding may mean a species may not be able to adapt to [[changes]] in environmental conditions. Each individual will have similar [[immune]] systems, as immune systems are genetically based. Where a [[species]] becomes endangered, the population may fall below a minimum whereby the forced interbreeding between the remaining animals will result in [[extinction]].

The reduced genetic [[diversity]] that results from inbreeding may mean a species may not be able to adapt to [[changes]] in environmental conditions. Each individual will have similar [[immune]] systems, as immune systems are genetically based. Where a [[species]] becomes endangered, the population may fall below a minimum whereby the forced interbreeding between the remaining animals will result in [[extinction]].

Natural breedings include inbreeding by [[necessity]], and most animals only [[migrate]] when [[necessary]]. In many cases, the closest available [[mate]] is a mother, sister, grandmother, father, brother, or grandfather. In all cases, the environment presents stresses to remove those [[individuals]] who cannot [[survive]] because of illness from the population.

Natural breedings include inbreeding by [[necessity]], and most animals only [[migrate]] when [[necessary]]. In many cases, the closest available [[mate]] is a mother, sister, grandmother, father, brother, or grandfather. In all cases, the environment presents stresses to remove those [[individuals]] who cannot [[survive]] because of illness from the population.

There was an assumption that wild populations do not inbreed; this is not what is observed in some cases in the [[wild]]. However, in species such as horses, animals in wild or [http://en.wikipedia.org/wiki/Feral feral] conditions often drive off the young of both [[genders]], thought to be a [[mechanism]] by which the species instinctively avoids some of the genetic [[consequences]] of inbreeding. In general, many [[mammal]] species including humanity's closest [[primate]] relatives avoid close inbreeding possibly due to the deleterious effects.[http://en.wikipedia.org/wiki/Inbreeding]

There was an assumption that wild populations do not inbreed; this is not what is observed in some cases in the [[wild]]. However, in species such as horses, animals in wild or [https://en.wikipedia.org/wiki/Feral feral] conditions often drive off the young of both [[genders]], thought to be a [[mechanism]] by which the species instinctively avoids some of the genetic [[consequences]] of inbreeding. In general, many [[mammal]] species including humanity's closest [[primate]] relatives avoid close inbreeding possibly due to the deleterious effects.[https://en.wikipedia.org/wiki/Inbreeding]

[[Category: Biology]]

[[Category: Biology]]