Breeding back is a form of artificial selection by the deliberate selective breeding of domestication (but not exclusively) animals, in an attempt to achieve an animal breed with a phenotype that resembles a wild type ancestor, usually one that has gone extinct. Breeding back is not to be confused with dedomestication.
Though bred-back breeds may be very similar to the extinct wild type in phenotype, ecological niche, and to some extent genetics, the gene pool of that wild type was different prior to its extinction. Even the superficial authenticity of a bred-back animal depends on the particular stock used to breed the new lineage. As a result of this, some breeds, like Heck cattle, are at best a vague look-alike of the extinct wild type aurochs, according to the literature.[Cis van Vuure: Retracing the Aurochs – History, Morphology and Ecology of an extinct wild Ox. 2005. ]
Background
The aim of breeding back programs is to restore the wild traits which may have been unintentionally preserved in the lineages of domesticated animals. Commonly, not only the new animal's phenotype, but also its ecological capacity, are considered in back-breeding projects, as hardy, "bred back" animals may be used in certain conservation projects. In nature, usually only individuals well suited to their natural circumstances will survive and reproduce, whereas humans select animals with additional attractive, docile or productive characteristics, protecting them from the dangers once found in their ancestral environment (predation, drought, disease, extremes of weather, lack of mating opportunities, etc.). In such cases, selection criteria in nature differ from those found in domesticated conditions. Because of this, domesticated animals often differ significantly in
phenotype, behaviour and
genetics from their wild forerunners. It is the hope of breeding-back programs to re-express, within a new breeding lineage, the wild, ancient traits that may have "lain buried" in the DNA of domestic animals.
In many cases, the extinct wild type ancestors of a given species are known only through skeletons and, in some cases, historical descriptions, making their phenotype poorly understood. Given that situation, there is currently no certainty of achieving success with a back-breeding attempt, and any results must be reviewed with great caution. In order to test genetic closeness, DNA (both mitochondrial and nuclear DNA) of the breeding animals must be compared against that of the extinct animal.
Successful breeding back might be possible: humans have selected animals only for superficial traits, and as a rule did not intentionally change less-observable traits, such as metabolic biochemistry.
Natural selection might serve as an additional tool in creating "authentic" robustness, "authentic" behaviour, and perhaps, the original phenotype as well. In some cases, a sufficient predator population would be necessary to enable such a selection process; in today's Europe, where many breeding-back attempts take place, this predator population is largely absent.
Use
Bred-back breeds are desirable in conservation biology, as they may fill an ecological gap left open by the extinction of a wild type due to human activities. As long as food preference, behaviour, robustness, defence against predators, hunting or foraging instincts and phenotype are the same as in the wild type, the bred-back phenotype will function similarly in the ecosystem. Releasing such animals into the wild would re-fill the previously empty niche, and allow a natural dynamic among the various species of the ecosystem to re-establish. However, not all breeding-back attempts will result in an animal that is closer to the wild type than are primitive domestic breeds. For example, Heck cattle bear less resemblance to the aurochs than do many Iberian
bull fighting.
Examples
Aurochs
Ideas for creating an
aurochs-like animal from domestic cattle have been around since 1835. In the 1920s,
Heinz Heck and
Lutz Heck tried to breed an aurochs look-alike, using central European dairy breeds and southern European cattle. The result, Heck cattle, are hardy, but differ from the aurochs in many respects, although a resemblance in colour and, less reliably, horns has been achieved.
From 1996 onwards, Heck cattle have been crossed with "primitive" Iberian breeds like
Sayaguesa Cattle and fighting cattle, as well as the very large Italian breed
Chianina, in a number of German reserves, in order to enhance the resemblance to the aurochs. The results are called
Taurus Project, being larger and longer-legged than Heck cattle and having more aurochs-like horns. Another of the projects to achieve a type of cattle that resembles the aurochs is the
TaurOs Project, using primitive, hardy southern European breeds, specifically Limia, Maremmana primitivo, Maronesa, Podolica, Sayaguesa and Pajuna.
European wild horse
The Polish
Konik horse is often erroneously considered the result of a breeding-back experiment to "recreate" the
phenotype of the
Tarpan. The Konik is actually a hardy
landrace breed originating in Poland, which was called
Panje horse before agriculturist
Tadeusz Vetulani coined the name "Konik" in the 1920s. Vetulani started an experiment to reconstruct the Tarpan using Koniks; ultimately, his stock made only a minor contribution to the present-day Konik population.
[Tadeusz Jezierski, Zbigniew Jaworski: Das Polnische Konik. Die Neue Brehm-Bücherei Bd. 658, Westarp Wissenschaften, Hohenwarsleben 2008, ]
During the Second World War, the Heck brothers crossed Koniks with Przewalski's horses and ponies, such as the Icelandic horse and the Gotland pony; the result is now called the Heck Horse. During recent decades, Heck horses have been continually crossed with Koniks, making the two phenotypes at present nearly indistinguishable, excepting that the Heck horse tends to have a lighter build.[Bunzel-Drüke, Finck, Kämmer, Luick, Reisinger, Riecken, Riedl, Scharf & Zimball: "Wilde Weiden: Praxisleitfaden für Ganzjahresbeweidung in Naturschutz und Landschaftsentwicklung]
Pigs
Boar–pig hybrids, which are hybrids of
and
and exist as an invasive species throughout Eurasia, the Americas, Australia, and in other places where European settlers imported wild boars to use as game animals, are also used for selective breeding to re-create the type of pigs represented in prehistoric artworks dating from the
Iron Age and earlier in ancient Europe. A project to create them, under the name of the
Iron Age pig, started in the early 1980s by crossing a male wild boar with a
Tamworth pig sow to produce an animal resembling what Iron Age pigs are believed to have looked like.
Iron Age pigs are generally only raised in Europe for the specialty meat market, and in keeping with their heritage are generally more aggressive and harder to handle than
purebred domesticated pigs.
Quagga
The
Quagga Project is an attempt, based in
South Africa, to breed animals which strongly resemble the now-extinct
quagga, a subspecies of the
plains zebra which died out in 1883. Accordingly, the project is limited to selecting for the physical appearance of the original, as recorded by twenty-three mounted specimens, many contemporary illustrations, and a number of written accounts of the animals.
[ The Quagga Project explained]
The two most noticeable characteristics of the quagga, fewer stripes and a darker pelage, are frequently observed to varying degrees in wild plains zebra populations. Animals with these two traits have been sought out for the Quagga Project breeding programme.
The project has been criticized for its focus on the morphological characteristics of the quagga, as the extinct animal may have possessed unrecorded behavioral or non-visible traits that would be impossible to reliably breed back from plains zebras.
Wolf
Although the
wolf, the wild ancestor of domestic dogs, is not extinct, its phenotype is the target of several developmental breeds including the Northern Inuit Dog and the
Tamaskan Dog. They are all crossbreeds of
, Alaskan Malamutes, and
Husky; selected for phenotypic wolf characteristics, the hybrids are then backbred to improve the "look-alike" effect. These new breeds may be viewed as breeding-back attempts as well.
Galápagos giant tortoise
In 2012, several hybrids of the Volcán Wolf and extinct Floreana giant tortoise subspecies were discovered on Isabela Island in the Galápagos Archipelago, a territory of
Ecuador. It is believed that sailors left these tortoises on the island during their travels in the early 19th century.
In 2017, back breeding efforts began to help the hybrids regain genetic purity of the Floreana subspecies.
By 2023, 400 Floreana offspring have been hatched from these hybrids on Santa Cruz Island, with plans to release these back bred animals into the wilds of
Floreana Island to regain their niche following the successful extirpation of
invasive species.
See also
Further reading
-
Koene, P., & Gremmen, B. (2001). Genetics of dedomestication in large herbivores. In 35th ISAE Conference, Davis, California, 2001 (pp. 68–68).
External links
