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Dog breeds, Canid Hybrid |
Canid hybrids are the result of interbreeding between two different members of the canine family (Canidae).
Many members of the Dog family can interbreed to produce fertile offspring.
Molecular analysis indicates 4 divisions of canids:
The wolf, coyote, jackal, and domestic Dog (including the dingo) all have 78 chromosomes arranged in 39 pairs. This allows them to hybridise freely (barring size or behavioural constraints) and produce fertile offspring. The wolf, coyote, and golden jackal diverged around 3 to 4 million years ago. Other members of the Dog family diverged 7 to 10 million years ago and are less closely related and connot hybridise with the wolf-like canids: the yellow Jackal has 74 chromosomes, the red fox has 38 chromosomes, the raccoon Dog has 42 chromosomes, and the Fennec fox has 64 chromosomes. Although the African Wild Dog has 78 chromosomes, it is considered distinct enough to be placed in its own genus.
(Note: It may be that foxes cannot hybridize with Dogs but, as crosses between horses and zebras demonstrate, differences in chromosome number are not the reason. Viable hybrids between species are possible regardless of chromosome number differences provided the gene combination in the hybrid allows for embryonic development to birth. Large differences in chromosome number, however, would make hybrid bitches so poorly fertile as to be essentially sterile. Male hybrids would be sterile due to a phenomenon called Haldane's Rule.)
In The Variation Of Animals And Plants Under Domestication, Charles Darwin wrote:
In Darwinism An Exposition Of The Theory Of Natural Selection With Some Of Its Applications (1889), Alfred Russel Wallace commented:
(Note: this deterioration was probably the result of inbreeding among the hybrid offspring)
Dog hybrids kept as pets are prohibited in many jurisdictions or are classed as wild animals and must be housed in the same way as purebred wolves. For example, hybrids of the domestic Dog with the wolf, coyote, dingo, jackal, fox, dhole, African Wild Dog, or Raccoon Dog are prohibited in the State of Hawaii (this legislation does not take into account the impossibility of some of the hybrids listed).
People wanting to improve domestic Dogs have sometimes bred them back to wolves. This compensates for inbred genetic problems in domestic Dogs, but wolf-Dog hybrids are dominant in adulthood and less domesticable. Grey wolves have been crossed with wolf-like Dogs such as German Shepherd Dogs and Alaskan Malamutes. Many problems occur because the owner expects them to behave like a domestic Dog and is unaccustomed to wolf-type behaviour. In parts of Europe, the declining wolf population naturally hybridises with stray and feral domestic Dogs, resulting in mongrel populations and further endangering the natural wolf.
There are a number of wolf-Dog hybrid breeds in development, for example, the Saarlooswolfhond breed is possibly derived from wolf-Dog hybrids. The initial hybrid offspring are generally back-crossed to domestic Dogs to maintain a domestic temperament and consistent conformation. First-cross wolf-Dog hybrids are popular in the USA, but retain many wolf-like traits.
Contrary to popular myth, Dogs cannot successfully interbreed with red foxes. Dogs have 78 chromosomes, but red foxes have only 38 chromosomes. This severe mismatch is a barrier to hybridisation.
An unconfirmed female terrier/fox hybrid was reported (and later euthanized) in the UK. British gamekeeper folklore claims that Terrier bitches can produce offspring with Dog Foxes. The supposed hybrids (known as a dox) are natural variation in the domestic Dog. There has been a reported cross between a domestic Dog and a South American fox, but the latter was a fox-like wolf and not a true fox.
In Saskatchewan, Canada there was another reported dox, this time a female miniature sheltie with a wild fox. There was a litter of three, but only one survived. The surviving (a female) was sterile, and looked like an almost pure fox, with slight variations.
In Origin of Species (1859), Charles Darwin wrote:
Coy-Dogs (male coyote/female Dog) can occur naturally as female coyotes are more likely to meet male Dogs than meet male coyotes. CoyDogs were once believed to be present in large numbers in Pennsylvania due to a declining Coyote population and a burgeoning domestic Dog population. Most supposed hybrids were naturally occurring red or blond color variations of the Coyote or were feral Dogs. The breeding cycles of Dogs and coyotes are not synchronized and this makes interbreeding uncommon. If interbreeding had been common, each successive generation of the Coyote population would have acquired more and more Dog-like traits.
Coyotes are solitary by nature and this trait is carried across to coyote-Dog hybrids. This can result in problematical and unsociable behaviour which makes them generally unsuited as pets. As a result, they may be abandoned or allowed to stray and be absorbed into the feral Dog or coyote population.
Coyotes have also been crossed with Australian dingoes in zoological gardens.
The Australian Dingo (a feral, rather than wild, species) hybridises freely with domestic Dogs. This is now so widespread that many dingoes are now mongrels. Some dingo hybrids have been deliberately bred as pets, but are turned loose due to behavioural problems. These hybrids are accepted back into the wild dingo population where they breed with pure dingoes. In some parts of Australia, up to 80% of dingoes are hybrids. Dingoes are distinguishable from domestic Dogs through DNA and through having longer teeth and longer muzzles.
The Australian Kelpie sheepDog is widely believed to be a hybrid of dingo and Border Collie, but this is not upheld by breed documentation.
The mating of a male Dog and a female coyote results in a Dogote. There has been one report of a Dogote which arose from a male German Shepherd/female coyote mating in the wild. Hybrid pups were found after a female coyote was shot. The adult Dogotes resembled a German Shepherd in color.
Coyotes are solitary by nature and this trait is carried across to Dog-coyote hybrids resulting in problematical or unsociable behaviour.
Coy-wolves (Coyote/Wolf) have occurred in captivity or, rarely, in the wild where the choice of same-species mates has been limited. Coyote/Red Wolf hybrids have been found. Some consider that the American Red Wolf is not a true species because it can hybridize with both the Grey Wolf and the Coyote; however, it is now known that hybridization between species (in general) happens more often than previously thought. Some consider it a Grey Wolf/Coyote hybrid and use this argument to prevent conservation of the Red Wolf. Some hybridization occurred when pure Red Wolves were in decline and interbred with the more numerous Coyotes. The species boundary is often preserved by geographic or behavioural separation, not by genetic separation.
The Wolf and Jackal can interbreed and produce fertile hybrid offspring. Coyote/Jackal Hybrids have also been bred as pets by Wolf-Dog enthusiasts. Dogs have been crossed with golden jackals; however, they cannot produce fertile offspring with yellow jackals as the latter have only 74 chromosomes compared to 78 in the Dog. It is also thought that Pharoanic Egyptians crossbred domestic Dogs with jackals, producing a jackal?-Dog that resembled the god Anubis.
(Note: Wild horses have 66 chromosomes. Domestic horses have 64. Wild horses and domestic horses can interbreed and produce fertile hybrids. The reason golden jackals differ in chromosome number is most likely because golden jackals have 2 pairs of chromosomes that are twice as long but contain similar gene content as 4 pairs of Dog chromosomes. This might reduce fertility but it would not likely completely sterilize golden jackal-Dog hybrids.)
In The Variation Of Animals And Plants Under Domestication Charles Darwin wrote:
In Russia, Dog/Jackal hybrids were bred as sniffer Dogs because Jackals have a superior sense of smell and Huskies are good cold climate Dogs. As well as a superior sense of smell, important at low temperatures where substances are less volatile and therefore less pungent, Sulimov Dogs are small sized and can work in confined spaces. When tired, their normally curled tails droop, making it clear to the handler that the Dog needs to be rested.
The jackal hybrids were bred by senior researcher Klim Sulimov at the D.S. Likhachev Scientific Research Institute for Cultural Heritage and Environmental Protection in Russia.
Male Jackal pups had to be fostered on a Husky bitch in order to imprint the Jackals on Dogs. Female Jackals accepted male Huskies more easily. The half-bred Jackal-Dogs were hard to train and were bred back to Huskies to produce quarter-bred hybrids (quadroons). These hybrids were small, agile, trainable and had excellent noses. They are called Sulimov Dogs after their creator and may one day be registered as a working breed of Dog. Twenty-five jackal-Dog hybrids are used by Aeroflot at Sheremetevo Airport in Moscow.