Selective breeding in domesticated animals is the process of developing a cultivated breed over time. Domesticated animals, plants, and other organisms are those whose collective behavior, life cycle, or physiology has been altered as a result of their breeding and living conditions being under human control for multiple generations. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anenomes) Placozoa (trichoplax) Subregnum Bilateria (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... A breed is a domesticated subspecies or infrasubspecies of an animal. ...

Selective Breeding Methods

In general, the owners of the animals use three strategies to refine local populations:

1. Isolation. There must be a period in which the members of the group are relatively fixed, so that no new genetic material comes in. Without genetic isolation of the group, the differentiation that creates a new breed cannot take place.
2. Artificial selection. Breeders must prevent random mating from coming about, and limit mating to those individuals who exhibit desired characteristics. One logical consequence of this isolation is the next characteristic: inbreeding.
3. Inbreeding. Ordinarily those who are controlling the artificial breeding will find it necessary at some stage to employ a degree of linebreeding (mating within one bloodline, or strain) or inbreeding (mating closely related individuals), to facilitate the weeding-out of undesired characteristics and the fixation of desired traits. Inbreeding and linebreeding are controversial aspects of artificial selection, but have been practiced for centuries.

The Appaloosa horse, which was developed by the Nez Percé Indians in the Northwest United States, provides an example. The Spanish colonists had established horse breeding in what is now New Mexico by about 1600, and the Spaniards of that era were known to have horses with spotted coats. By 1806 (when they are mentioned in journals kept by the Lewis and Clark expedition) the Nez Percé were observed to have developed strong, hardy, spotted horses. The Appaloosa is a horse breed, one of the color breeds, in which the breed has one of several distinct patterns of spots. ... Binomial name Equus caballus Linnaeus, 1758 The horse (Equus caballus) is a sizeable ungulate mammal, one of ten modern species of the genus Equus. ... Nez Percé warrior on horse, 1910 The Nez Percé or Nez Perce (pronounced as in French, or ) are a tribe of Native Americans who inhabited the Pacific Northwest region of the United States at the time of the Lewis and Clark Expedition. ... Official language(s) None, English and Spanish de facto Capital Santa Fe Largest city Albuquerque Area  - Total  - Width  - Length  - % water  - Latitude  - Longitude Ranked 5th 315,194 km² 550 km 595 km 0. ... // Events January January 1 - Scotland adopts January 1st as being New Years Day February February 17 - Giordano Bruno burned at the stake for heresy in Rome July July 2 - Battle of Nieuwpoort: Dutch forces under Maurice of Nassau defeat Spanish forces under Archduke Albert in a battle on the... 1806 was a common year starting on Wednesday (see link for calendar). ... The Lewis and Clark expedition (1804-1806) was the first American overland expedition to the Pacific coast and back. ...

It is not known if the Nez Percé practiced inbreeding, but they were reputed to geld stallions judged unsuitable for breeding, and to trade away mares likewise unsuitable for breeding, which accomplishes the goals of isolation and artificial selection.

In Europe, the first use of this process was recorded in mid 18th century England, by Robert Bakewell and Thomas Coke

Closed vs. open studbook

A studbook is the official registry of approved individuals of a given breed kept by a breed association. It is said to be "closed" if individuals can be added only if their parents were both registered. It is said to be "open" if individuals can be added without their parents being registered, such as by inspection.

Studbooks have been kept for centuries; the concept of the breed associations and clubs is more recent. Most of the "purebred horses" have open studbooks. For example, a "purebred" Arabian mare can be "examined" by the Trakehner authorities; if she is found acceptable, her offspring can be registered as Trakehner. By contrast, the studbooks of purebred dogs only remain open if the breed is under development or if there is deemed to be an insufficient genepool. An Arabian mare The Arabian horse first appeared in the Arabian Peninsula at least 2,500 years B.C.E. They were carefully bred to maintain desirable features (e. ... A Trakehner can also refer to a type of Cross country jump The Trakehner Trakehner is a horse breed. ...

Crossbreeding and backbreeding

In some registries, breeders may apply for permission to crossbreed other breeds into the line to emphasize certain traits, to keep the breed from extinction or to alleviate problems caused in the breed by inbreeding from a limited set of animals. A related preservation method is backbreeding, used by some equine and canine registries, in which crossbred individuals are mated back to purebreds to eliminate undesirable traits acquired through the crossbreeding. A breed registry, also known as a stud book, is an official list of animals within a specific breed whose parents are known. ... Crossbreeding is the process of creating hybrids (also known as crossbreeds, or a description of the lineage of that which has undergone hybridization. ... In biology and ecology, extinction is the ceasing of existence of a species or group of taxa. ... Inbreeding is breeding between close relatives. ...

Some horse societies accept crossbreds who meet certain criteria onto the breed registry.

Purebred Cats, Dogs and the Debate over 'Breed Purity'

Most purebred cats and dogs of breeds recognized by all-breed club registries are controlled by "closed studbooks". In a number of modern breeds recognized by the kennel clubs, there are high incidences of specific genetic diseases or disorders and sometimes increased susceptibility to other diseases, reduced litter sizes, reduced lifespan, inability to conceive naturally, etc. This came about because: A breed is a domesticated subspecies or infrasubspecies of an animal. ... A kennel club (known as a kennel council or canine council in some countries) is an organization for canine affairs that concerns itself with the welfare, promotion, and maintenance of more than one breed of dog. ...

1. Many breeds have been established with too few foundation dogs or ones that were already too closely related, or both
2. There was artificial isolation: the registries (stud books) are closed for most breeds; therefore one cannot introduce diversity from outside the existing population.
3. Most selective breeding practices have the effect of reducing the diversity further. In addition, in the show world, breeding specimens are often selected on the basis of aesthetic criteria only, without regard for soundness.
4. Even if the foundation dogs were sufficiently diverse genetically, almost no one knows how their genetic contributions are distributed among the present day population, consequently, breeding is done without regard to conserving these contributions, which may be of value to the general health and survival of the breed.

Similar problems affect purebred cats, however to a lesser extent since selective breeding in cats has not been practiced for nearly the length of time that it has been in dogs. The purebred cat is a relatively new creature; some breeds of cats have existed less than fifty years. In a dog show, judges familiar with specific dog breeds evaluate individual dogs for how well they conform to published breed standards, hence the more accurate term is conformation show (or, sometimes, breed show). ...

Purebreds

The very idea of 'breed purity' often strikes an unpleasant chord with modern animal fanciers because it is reminiscent of nineteenth-century eugenics notions of the "superior strain" which were supposedly exemplified by human aristocracies and thoroughbred horses. The application of theories of eugenics has had far-reaching consequences for human beings, and the observable phenomenon of hybrid vigor stands in sharp contrast. Eugenics is the self-direction of human evolution: Logo from the Second International Congress of Eugenics, 1921, depicting it as a tree which unites a variety of different fields. ... Heterosis is increased strength of different characteristics in hybrids; the possibility to obtain a better individual by combining the virtues of its parents. ...

The idea of the superior strain was that by "breeding the best to the best," employing sustained inbreeding and selection for "superior" qualities, one would develop a bloodline superior in every way to the unrefined, base stock which was the best that nature could produce. Naturally the purified line must then be preserved from dilution and debasement by base-born stock. This theory was never completely borne out. It can be said that when the ideal of the purified lineage or aesthetic type is seen as an end in itself, the breed suffers over time. The same issues are raised in the world of purebred cats. A show cat (Manx) being judged at a show A show cat (also known as a purebred or pedigreed cat) is one that has been judged to be close to the physical ideal for its breed standard at a cat show. ...

His claim that selective breeding had been successful in producing change over time was one of the key arguments proposed by Charles Darwin to support his theory of natural selection in his acclaimed yet controversial work Origin of Species. Here, the “selective” does not mean breeding selected in a humanly controlled fashion. In his lifetime Charles Darwin gained international fame as an influential scientist examining controversial topics. ... Natural selection is the metaphor Charles Darwin used in 1859 to name the process he postulated to drive the adaptation of organisms to their environments and the origin of new species. ... The 1859 edition of On the Origin of Species First published in 1859, The Origin of Species (full title On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life) by British naturalist Charles Darwin is one of the pivotal...

See also

• Artificial selection
• Breed registry
• Breeding