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Line 18: − − == Inbreeding in animals == − − Breeding closely related animals allows a breeder to select desired traits and create a population where every individual has those traits. However, sometimes deleterious traits also "hitchhike" along with the desired traits as a result of inbreeding. This can lead to inbreeding depression.<ref>Sarah Hartwell wrote, "Deleterious genes become widespread and the breed loses vigor." [http://www.dogbreedinfo.com/inbreeding.htm]</ref> As an example, [[Pug]]s are a dog breed which has been bred for thousands of years, but genetic disorders relating to the eyes are common in the breed. [[Manx]] cats, known for having short tails, arose naturally due to [[genetic drift]], but problems such as spina bifida are very common. − − One way to overcome inbreeding depression is by periodically introducing new genetic variation in a process known as outcrossing, where members of the breed are mated with individuals from outside the breed. This decreases the "purity" of the line, but can reduce the prevalence of genetic disorders.
again, moving up plain English ahead of jargon-laden stuff
'''Inbreeding''' is breeding between closely related individuals in a population. In humans, close inbreeding is referred to as [[incest]].
'''Inbreeding''' is breeding between closely related individuals in a population. In humans, close inbreeding is referred to as [[incest]].
Breeding closely related animals allows a breeder to select desired traits and create a population where every individual has those traits. However, sometimes deleterious traits also "hitchhike" along with the desired traits as a result of inbreeding. This can lead to inbreeding depression.<ref>Sarah Hartwell wrote, "Deleterious genes become widespread and the breed loses vigor." [http://www.dogbreedinfo.com/inbreeding.htm]</ref> As an example, [[Pug]]s are a dog breed which has been bred for thousands of years, but genetic disorders relating to the eyes are common in the breed. [[Manx]] cats, known for having short tails, arose naturally due to [[genetic drift]], but problems such as spina bifida are very common.
One way to overcome inbreeding depression is by periodically introducing new genetic variation in a process known as outcrossing, where members of the breed are mated with individuals from outside the breed. This decreases the "purity" of the line, but can reduce the prevalence of genetic disorders.
== Mathematical definition ==
== Mathematical definition ==
On the other hand, if there are no deleterious alleles and the mutation rate is low, inbreeding is not necessarily harmful to the population. For example, [[creationism|creationists]] argue that, since [[Adam]] and [[Eve]] were created perfect and mutation rates were lower before the [[Flood]], marriage and breeding between Adam and Eve's descendants was not harmful or immoral in the way it is today.
On the other hand, if there are no deleterious alleles and the mutation rate is low, inbreeding is not necessarily harmful to the population. For example, [[creationism|creationists]] argue that, since [[Adam]] and [[Eve]] were created perfect and mutation rates were lower before the [[Flood]], marriage and breeding between Adam and Eve's descendants was not harmful or immoral in the way it is today.
== Notes ==
== Notes ==
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