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Breeding back is a form of artificial selection by the deliberate selective breeding, mostly of domestic animals, in an attempt to achieve an animal breed with a phenotype that resembles a wildtype ancestor, usually one that is extinct. Breeding back is not to be confused with dedomestication. It must be kept in mind that a breeding-back breed may be very similar to the extinct wild type in phenotype, ecological niche, and to some extent genetics, but the initial gene pool of that wild type is lost forever with its extinction. It is not truly possible for a breeding back attempt to actually recreate an extinct wild type that is the breeding target, as an extinct wild type cannot be resurrected via selective breeding alone. Furthermore, even the outward authenticity of a bred-back type depends on the quality of the stock used as the foundation of the project. As a result, some breeds, like Heck cattle, are at best a vague look-alike of the extinct wildtype aurochs, according to the literature.〔Cis van Vuure: Retracing the Aurochs – History, Morphology and Ecology of an extinct wild Ox. 2005. ISBN 954-642-235-5〕 == Background == It is the target of breeding back to restore the wild traits that may have been preserved in domestic animals within one breeding lineage. Commonly, only the phenotype but also the ecological capacity are considered in breeding back projects, because hardy breeding back results are used in certain conservation projects. In nature, usually only individuals suited to the natural circumstances can survive and reproduce, while humans select those with additional attractive, docile or productive characteristics. Therefore, selection criteria in nature versus those in domestic conditions are different and domesticated animals often differ significantly in phenotype, behaviour and genetics from their wild forerunners. It is the target of breeding back to re-create the wild traits that may have been preserved in domestic animals within one breeding lineage. In many cases, the extinct wild type ancestors of a given species are only known through skeletons and, in some cases, historical descriptions, so their phenotype is not directly accessible. Therefore, there is no certainty of success with a breeding back attempt and the results must be reviewed with caution. In order to test genetic closeness, both mitochondrial DNA and nuclear DNA have to be accessible. However, success is possible: humans only selected for superficial characters and as a rule did not change inner mechanisms such as digestion.〔 Further, since many domestic animals show a behaviour that is derived from their wild ancestors (such as the herding instinct of cattle or the social instincts of dogs), and are fit to survive under natural circumstances, as evidenced by the many feral populations of many domestic animals, it can be presumed that back-bred animals will function like their wild ancestors.〔 For example, food choice should be the same in domestic and wild types. Natural selection could serve as an additional tool in creating authentic robustness, behaviour and maybe also phenotype. For large herbivores, a sufficient predator population would also be necessary to support such a process, but this largely is not present in current Europe, where many breeding back projects are conducted. There is a difference between creating a look-alike breed from domestic animals and creating a look-alike via artificial selection of individuals of a different species or subspecies that may resemble the animal that is targeted. For example, the Quagga was an independent subspecies of the plains zebra, and has no descendants which preserved its features. Thus, the Quagga Project tries to breed a look-alike out of living plains zebras which have fewer stripes than average, selecting for reduced striping. The resulting animal will bear only a superficial resemblance to the extinct Quagga. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Breeding back」の詳細全文を読む スポンサード リンク
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