Breeding back

[1] The aim of breeding back programs is to restore the wild traits which may have been unintentionally preserved in the lineages of domesticated animals.

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.

[1] Further, since many domestic species show behaviours derived from their wild ancestors (such as the herding instinct of cattle or the social instincts of dogs), and are fit to survive outside the sphere of human interference (as evidenced by the many feral populations of various domestic animals), it can be presumed that "bred back" animals might be able to function like their wild ancestors.

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.

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.

[3] Boar–pig hybrids, which are hybrids of wild boars and domestic pigs 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.

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.

[5] 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.

[6] 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.

They are all crossbreeds of German Shepherds, Alaskan Malamutes, and Huskies; selected for phenotypic wolf characteristics, the hybrids are then backbred to improve the "look-alike" effect.

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.

Heck cattle were bred in the 1920s to resemble the aurochs.
VOA report about the Quagga Project
Taurus cattle bull in the Lippeaue Reserve, Germany
Heck horse in Haselünne, Germany
A Tamaskan Dog , bred to visually resemble a wolf
Volcán Wolf tortoises hybridised with the Floreana Island tortoises, allowing for breeding back to restore the extinct subspecies.