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bred of parents not closely related; having parents of different classes or tribes

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/08/09 23:05:59」(JST)

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Outcrossing or outbreeding is the practice of introducing unrelated genetic material into a breeding line. It increases genetic diversity, thus reducing the probability of an individual being subject to disease or reducing genetic abnormalities.

It is used in line breeding, where animals carry a common ancestor in their pedigrees and are bred together, to restore vigor or size and fertility to a breeding line. It is a form of "inbreeding" which is the production of offspring by parents more closely related than the average.^[1]

Outcrossing is now the norm of most purposeful animal breeding, contrary to what is commonly believed.^[2]^[3]^[4]^[5] The outcrossing breeder intends to remove the traits by using "new blood". With dominant traits, one can still see the expression of the traits and can remove those traits whether one outcrosses, line breeds or inbreds. With recessive traits, outcrossing allows for the recessive traits to migrate across a population. The outcrossing breeder then may have individuals that have many deleterious genes that may be expressed by subsequent inbreeding. There is now a gamut of deleterious genes within each individual in many dog breeds.^[6]

Increasing the variation of genes or alleles within the gene pool may protect against extinction by stressors from the environment. For example, in this context, a recent veterinary medicine study tried to determine the genetic diversity within cat breeds.^[7]

Outcrossing is believed to be the "norm" in the wild.^[6] Outcrossing in plants is usually enforced by self-incompatibility.

Breeders inbreed within their genetic pool, attempting to maintain desirable traits and to cull those traits that are undesirable. When undesirable traits begin to appear, mates are selected to determine if a trait is recessive or dominant. Removal of the trait is accomplished by breeding two individuals known not to carry it.^[8]

Gregor Mendel used outcrossing in his experiments with flowers. He then used the resulting offspring to chart inheritance patterns, using the crossing of siblings, and backcrossing to parents to determine how inheritance functioned.^[9]

References

^ Guy Fawkes Horses Retrieved on 2009-8-1^{[dead link]}
^ Cat Fanciers: American Curl: Cat Breed FAQ
^ The Balinese Cat in the UK
^ Inbreeding: A Personal Point of View
^ Outcrossing in hunting dogs
^ ^a ^b Price
^ http://www.vgl.ucdavis.edu/lyons/index.php
^ [1]
^ Mendel's Paper (English - Annotated)

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1. 遺伝学およびゲノミクスのためのツール：研究用に育種された遺伝子改変マウス tools for genetics and genomics specially bred and genetically engineered mice
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4. 遺伝性痙性対麻痺 hereditary spastic paraplegia

English Journal

Cloning and molecular characterization of telomerase reverse transcriptase (TERT) and telomere length analysis of Peromyscus leucopus.

Zhao X1, Ueda Y2, Kajigaya S2, Alaks G3, Desierto MJ2, Townsley DM2, Dumitriu B2, Chen J2, Lacy RC3, Young NS2.
Gene.Gene.2015 Aug 15;568(1):8-18. doi: 10.1016/j.gene.2015.05.013. Epub 2015 May 9.
Telomerase reverse transcriptase (TERT) is the catalytic subunit of telomerase complex that regulates telomerase activity to maintain telomere length for all animals with linear chromosomes. As the Mus musculus (MM) laboratory mouse has very long telomeres compared to humans, a potential alternative
PMID 25962353

Reduction of ethanol intake by corticotropin-releasing factor receptor-1 antagonist in "heavy-drinking" mice in a free-choice paradigm.

Correia D1, Martynhak BJ, Pereira M, Siba IP, Ribeiro AF, Camarini R, Boerngen-Lacerda R.
Psychopharmacology.Psychopharmacology (Berl).2015 Aug;232(15):2731-9. doi: 10.1007/s00213-015-3909-y. Epub 2015 Mar 24.
RATIONALE: We hypothesized that the corticotropin-releasing factor (CRF) system is hyperresponsive in animals with high ethanol intake, which exhibits a reduction of ethanol intake when administered with a CRF1 receptor antagonist.METHODS: Outbred Swiss mice were subjected to a long-term, three-bott
PMID 25797192

Caffeine Improves Heart Rate Without Improving Sepsis Survival.

Bauzá G1, Remick D.
Shock (Augusta, Ga.).Shock.2015 Aug;44(2):143-8. doi: 10.1097/SHK.0000000000000399.
INTRODUCTION: Caffeine is consumed on a daily basis for its nervous system stimulant properties and is a global adenosine receptor antagonist. Because adenosine receptors have been found to play a major role in regulating the immune response to a septic insult, we investigated if caffeine consumptio
PMID 25944789

Japanese Journal

Genomic Mixing to Elucidate the Genetic System of Complex Traits

KOIDE Tsuyoshi,GOTO Tatsuhiko,TAKANO-SHIMIZU Toshiyuki
Experimental Animals 61(5), 503-509, 2012
… In order to overcome this problem, many recent genetic studies of complex traits have actively used outbred stocks of mice. … However, most of the available outbred stocks have a limited amount of genetic variation, because many stocks originate from Swiss mouse colonies. …
NAID 130001893576

マイクロサテライトマーカーを用いたマウスの遺伝学的モニタリングの試み : アウトブレッドマウス系統の場合

上野渉,飯名瑞希,海野あゆみ,早尾辰雄,西川哲
実験動物技術 46(2), 61-66, 2011-12-31
NAID 10030286825

Prevalence of Murine Norovirus Infection in Korean Laboratory Animal Facilities

KIM Jong Rhan,SEOK Seung Hyeok,KIM Dong Jae,BAEK Min-Won,NA Yi-Rang,HAN Ju-Hee,KIM Tae-Hyun,PARK Jae-Hak,TURNER Patricia V.,CHUNG Doo Hyun,KANG Byeong-Cheol
Journal of Veterinary Medical Science 73(5), 687-691, 2011
… In summary, 6.6% of inbred/outbred mice purchased from commercial vendors were seropositive, 9.6% of in-house colonies were seropositive and 27.0% of genetically modified mice (GMM) were seropositive. …
NAID 130000444750