Помесь

Labradoodle , помесь между пуделем и ретривер

Метис представляет собой организм с беспородных родителей двух разных пород, сортов или популяций. Скрещивание , иногда называемое «дизайнерским скрещиванием», представляет собой процесс разведения такого организма. В то время как скрещивание используется для поддержания здоровья и жизнеспособности организмов, безответственное скрещивание может также производить организмы более низкого качества или разбавлять чистокровный генофонд до исчезновения. данной породы организма. ^[1]

Домашнее животное неизвестного происхождения, для которого известен статус породы только одного родителя или дедушки или бабушки, также может называться помесью, хотя термин «смешанная порода» технически более точен. Ауткроссинг - это тип скрещивания, используемый внутри чистокровной породы для увеличения генетического разнообразия внутри породы, особенно когда необходимо избегать инбридинга .

В селекции животных гибриды - это скрещивания внутри одного вида, а гибриды - это скрещивания между разными видами. В терминологии селекции растений термин « скрещивание» встречается редко, и не используется универсальный термин, чтобы отличить гибридизацию или скрещивание внутри популяции от таковых между популяциями или даже между видами.

Дизайнерская помесь [ править ]

Дизайнерская помесь или дизайнерская порода - это помесь животных, у которых есть чистокровные родители, обычно зарегистрированные в реестре пород , но от двух разных пород . Эти животные являются результатом осознанного решения создать конкретное помесное животное. ^[2] Реже животное может иметь более двух чистых пород в своей родословной, но, в отличие от дворняги или дворняги , известно, что вся его родословная происходит от конкретных известных животных. Хотя этот термин наиболее известен применительно к определенным помесам собак.таким способом можно разводить других животных, таких как крупный рогатый скот, лошади, птицы и кошки. Некоторые заводчики кроссбредов создают автономный реестр пород для регистрации дизайнерских помесей, другие помеси могут быть включены в «приложение» к существующему реестру чистокровных пород. любая форма регистрации может быть первым шагом в регистрации и отслеживании родословных с целью выведения новой породы.

Примеры дизайнерских помесей

Англо-арабская лошадь является чистокровной / Арабская лошадь крест

Целью создания дизайнерских помесей обычно является одна или несколько из следующих причин:

1. to breed animals with heterosis, commonly known as "hybrid vigor",^[3]
2. to create animals with more predictable characteristics than mixed breed or mongrel breeding,
3. to avoid certain undesirable recessive traits that lead to genetic diseases that plague many purebred animals,
4. to develop an animal that combines what are viewed as the best traits of two or more breeds,^[3]
5. as the preliminary steps toward developing a new animal breed.^[2]

Breeders of designer crossbreds borrow the technical language from hybrid plant breeding: A first generation, 50–50 crossbred is an F1 cross.^[2] Subsequent generations may see a purebred animal crossed back on a crossbred, creating a 75/25 cross,^[2] or a BC1 or F1b "backcross."^[4] The breeding of two crossbreeds of the same combination of breeds, creating a F2 cross, an animal that is still a 50–50 cross, but it is the second filial generation of the combination.^[5] A F2 cross bred to an F2 cross creates a F3 cross. Similarly, a F2 animal bred to an F1 animal creates a F2b backcross. F3 crosses and greater are called "multi-generational" crosses.^[4] In dog breeding, three generations of reliable documented breeding can be considered a "breed" rather than a crossbreed.^[6]

There are disadvantages to creating designer crossbreeds, notably the potential that the cross will be of inferior quality or that it will not produce as consistent a result as would breeding purebred animals. For example, the Poodle is a frequent breed used in creation of designer crossbreeds, due to its non-shedding coat, but that trait does not always breed true when it is part of a designer cross.^[2] Also, because breeders of crossbred animals may be less careful about genetic testing and weeding out undesirable traits,^[6] certain deleterious dominant genes may still be passed on to a crossbreed offspring. In an F2 cross, recessive genetic traits may also return if the parent animals were both carriers of an undesired trait.

Crossbreeds in specific animals[edit]

Cats[edit]

The many newly developed and recognized breeds of domestic cat are crossbreeds between existing, well-established breeds (sometimes with limited hybridization with some wild species), to either combine selected traits from the foundation stock, or propagate a rare mutation without excessive inbreeding. However, some nascent breeds such as the Aegean cat are developed entirely from a local landrace population. Most experimental cat breeds are crossbreeds.

Cattle[edit]

In cattle, there are systems of crossbreeding. In many crossbreeds, one animal is larger than the other. One is used when the purebred females are particularly adapted to a specific environment, and are crossed with purebred bulls from another environment to produce a generation having traits of both parents.^[7]

Sheep[edit]

The large number of breeds of sheep, which vary greatly, creates an opportunity for crossbreeding to be used to tailor production of lambs to the goal of the individual stockman.^[8]

Llamas[edit]

Results of crossbreeding classic and woolly breeds of llama are unpredictable. The resulting offspring displays physical characteristics of either parent, or a mix of characteristics from both, periodically producing a fleeced llama. The results are increasingly unpredictable when both parents are crossbreeds, with possibility of the offspring displaying characteristics of a grandparent, not obvious in either parent.^[9]

Dogs[edit]

A crossbred dog is a cross between two (sometimes more) known breeds, and is usually distinguished from a mixed-breed dog, which has ancestry from many sources, some of which may not be known. Crossbreeds are popular, due to the belief that they have increased vigor without loss of attractiveness of the dog. Certain planned crossbreeding between purebred dogs of different breeds are now widely known as "designer dogs" and can produce puppies worth more than their purebred parents, due to a high demand.

Horses[edit]

Crossbreeding in horses is often done with the intent of ultimately creating a new breed of horse. One type of modern crossbreeding in horses is used to create many of the warmblood breeds. Warmbloods are a type of horse used in the sport horse disciplines, usually registered in an open stud book by a studbook selection procedure that evaluates conformation, pedigree and, in some animals, a training or performance standard. Most warmblood breeds began as a cross of draft horse breeds on Thoroughbreds, but have, in some cases, developed over the past century to the point where they are considered to be a true-breeding population and have a closed stud book. Other types of recognized crossbreeding include that within the American Quarter Horse, which will register horses with one Thoroughbred parent and one registered Quarter Horse parent in the "Appendix" registry, and allow such animals full breed registration status as Quarter Horses if they meet a certain performance standard. Another well-known crossbred horse is the Anglo-Arabian, which may be produced by a purebred Arabian horse crossed on a Thoroughbred, or by various crosses of Anglo-Arabians with other Anglo-Arabians, as long as the ensuing animal never has more than 75% or less than 25% of each breed represented in its pedigree.

Hybrid animals[edit]

A hybrid animal is one with parentage of two separate species, differentiating it from crossbred animals, which have parentage of the same species. Hybrids are usually, but not always, sterile.^[10]

One of the most ancient types of hybrid animal is the mule, a cross between a female horse and a male donkey. The liger is a hybrid cross between a male lion and female tiger. The yattle is a cross between a cow and a yak. Other crosses include the tigon (between a male tiger and female lion) and yakalo (between a yak and buffalo). The Incas recognized that hybrids of Lama glama (llama) and Vicugna pacos (alpaca) resulted in a hybrid with none of the advantages of either parent.^[11]

At one time it was thought that dogs and wolves were separate species, and the crosses between dogs and wolves were called wolf hybrids. Today wolves and dogs are both recognized as Canis lupus, but the old term "wolf hybrid" is still used.

Mixed breeds[edit]

A mixed-breed animal is defined as having undocumented or unknown parentage, while a crossbreed generally has known, usually purebred parents of two distinct breeds or varieties. A dog of unknown parentage is often called a mixed-breed dog, "mutt" or "mongrel." A cat of unknown parentage is often referred to as a domestic short-haired or domestic long-haired cat generically, and in some dialects is often called a "moggie". A horse of unknown bloodlines is called a grade horse.

See also[edit]

• Artificial selection
• Canid hybrid
• Heterosis
• Introgression
• Selective breeding

References[edit]