White tigers are distinct for the normal coloration in that they lack the pheomelanin pigment that in normal tigers produces the orange color. They still produce the other color pigment, eumelanin, and hence are not considered albino. Compared to normal colored tigers without the white gene, white tigers tend to be somewhat bigger, both at birth and as fully grown adults. Kailash Sankhala, the director of the New Delhi Zoo in the 1960s, said "one of the functions of the white gene may have been to keep a size gene in the population, in case it's ever needed." Dark-striped white individuals are well-documented in the Bengal Tiger subspecies, also known as the Royal Bengal or Indian tiger (Panthera tigris tigris or P. t. bengalensis), and may also have occurred in captive Siberian Tigers (Panthera tigris altaica), as well as having been reported historically in several other subspecies. Currently, several hundred white tigers are in captivity worldwide, with about one hundred being found in India. Nevertheless, their population is on the increase.
The unusual white coloration of white tigers has made them popular in zoos and entertainment showcasing exotic animals. German-American magicians Siegfried & Roy became famous for breeding and training two white tigers for their performances, referring to them as "royal white tigers," the white tiger's association with the Maharaja of Rewa.
Martand Singh, the last Maharaja of Rewa, captured the first living white tiger observed in nature, during his 1950 visit to Govindgarh jungle at Rewa, Madhya Pradesh, India. With help from official veterinary experts, he attempted breeding the white tiger with colored female tigers. Though initial attempts failed, he did eventually succeed and created a second generation of white tigers. In time, this breeding population has been expanded around the world.
White Siberian tigers
The existence of white Siberian tigers has not been scientifically documented, despite occasional unsubstantiated reports of sightings of white tigers in the regions where wild Siberian tigers live. It may be that the white mutation does not exist in the wild Siberian tiger population: no white Siberian tigers have been born in captivity, despite the fact that the subspecies has been extensively bred during the last few decades (with much outbreeding between the different Siberian lineages for purposes of conservation genetics); a recessive allele should occasionally turn up in a homozygous state during such breeding, and in this particular case yield white tigers from normally-colored parents, but no such animals have been reported.
The famous white Siberian tigers found in captivity are actually not pure Siberian tigers. They are instead the result of Siberian tigers breeding with Bengal tigers. The gene for white coating is quite common among Bengal tigers, but the natural birth of a white Bengal tiger is still a very rare occasion in the wild, where white tigers are not bred selectively.
The white tiger is not considered a tiger subspecies, but rather a mutant variant of the existing tiger subspecies. If a pure white Siberian tiger were to be born, it would therefore not be selectively bred within the tiger conservation programs. It would, however, probably still be selectively bred outside the program in an effort to create more white Siberian tigers. Due to the popularity of white tigers, they are used to attract visitors to zoos.
Stripeless white tigers and golden tabby tiger
An additional genetic condition can remove most of the striping of a white tiger, making the animal almost pure white. One such specimen was exhibited at Exeter Change in England in 1820, and described by Georges Cuvier as "A white variety of Tiger is sometimes seen, with the stripes very opaque, and not to be observed except in certain angles of light." Naturalist Richard Lydekker said that, "a white tiger, in which the fur was of a creamy tint, with the usual stripes faintly visible in certain parts, was exhibited at the old menagerie at Exeter Change about the year 1820." Hamilton Smith said, "A wholly white tiger, with the stripe-pattern visible only under reflected light, like the pattern of a white tabby cat, was exhibited in the Exeter Change Menagerie in 1820.", and John George Wood stated that, "a creamy white, with the ordinary tigerine stripes so faintly marked that they were only visible in certain lights." Edwin Henry Landseer also drew this tigress in 1824.
The modern strain of snow white tigers came from repeated brother–sister matings of Bhim and Sumita at Cincinnati Zoo. The gene involved may have come from a Siberian tiger, via their part-Siberian ancestor Tony. Continued inbreeding appears to have caused a recessive gene for stripelessness to show up. About one fourth of Bhim and Sumita's offspring were stripeless. Their striped white offspring, which have been sold to zoos around the world, may also carry the stripeless gene. Because Tony's genome is present in many white tiger pedigrees, the gene may also be present in other captive white tigers. As a result, stripeless white tigers have appeared in zoos as far afield as the Czech Republic, Spain and Mexico. Stage magicians Siegfried & Roy were the first to attempt to selectively breed tigers for stripelessness; they owned snow-white Bengal tigers taken from Cincinnati Zoo (Tsumura, Mantra, Mirage and Akbar-Kabul) and Guadalajara, Mexico (Vishnu and Jahan), as well as a stripeless Siberian tiger called Apollo.
Stripeless white tigers were thought to be sterile until Siegfried & Roy's stripeless white tigress Sitarra, a daughter of Bhim and Sumita, gave birth. Another variation which came out of the white strains were unusually light-orange tigers called "golden tabby tigers". These are probably orange tigers which carry the stripeless white gene as a recessive. Some white tigers in India are very dark, between white and orange.
A white tiger's pale coloration is due to the lack of the red and yellow pigments that normally produce the orange coloration. This had long been thought to be due to a mutation in the gene for the tyrosinase enzyme. A knockout mutation in this gene results in albinism, the inability to make either pheomelanin or eumelanin, while the consequence of a less severe mutation in the same gene is the cause of a selective loss of pheomelanin, the so-called Chinchilla trait. The white phenotype in tigers had been attributed to this Chinchilla mutation in tyrosinase, and some publications prior to the 1980s refer to it as an albino gene for this reason. However, genomic analysis has demonstrated instead that a mutation in the SLC45A2 gene is responsible. The resultant single amino acid substitution in this transport protein, by a mechanism yet to be determined, causes the elimination of pheomelanin expression seen in the white tiger. This is a recessive trait, meaning that it is only seen in individuals that are homozygous for this mutation. Inbreeding promotes recessive traits and has been used as a strategy to produce white tigers in captivity.
The stripe color varies due to the influence and interaction of other genes. Another genetic characteristic makes the stripes of the tiger very pale; white tigers of this type are called snow-white or "pure white". White tigers, Siamese cats, and Himalayan rabbits have enzymes in their fur which react to temperature, causing them to grow darker in the cold. A white tiger named Mohini was whiter than her relatives in the Bristol Zoo, who showed more cream tones. This may have been because she spent less time outdoors in the winter. White tigers produce a mutated form of tyrosinase, an enzyme used in the production of melanin, which only functions at certain temperatures, below 37 °C (99 °F). This is why Siamese cats and Himalayan rabbits are darker on their faces, ears, legs, and tails (the color points), where the cold penetrates more easily. This is called acromelanism, and other cats breeds derived from the Siamese, such as the Himalayan and the snowshoe cat, also exhibit the condition. Kailash Sankhala observed that white tigers were always whiter in Rewa State, even when they were born in New Delhi and returned there. "In spite of living in a dusty courtyard, they were always snow white." A weakened immune system is directly linked to reduced pigmentation in white tigers.
Outside of India, inbred white tigers have been prone to crossed eyes, a condition known as strabismus, an example of which is "Clarence the cross-eyed lion", due to incorrectly routed visual pathways in the brains of white tigers. When stressed or confused, all white tigers cross their eyes. Strabismus is associated with white tigers of mixed Bengal x Siberian ancestry. The only pure-Bengal white tiger reported to be cross-eyed was Mohini's daughter Rewati. Strabismus is directly linked to the white gene and is not a separate consequence of inbreeding. The orange litter-mates of white tigers are not prone to strabismus. Siamese cats and albinos of every species which have been studied all exhibit the same visual pathway abnormality found in white tigers. Siamese cats are also sometimes cross-eyed, as are some albino ferrets. The visual pathway abnormality was first documented in white tigers in the brain of a white tiger called Moni after he died, although his eyes were of normal alignment. The abnormality is that there is a disruption in the optic chiasm. The examination of Moni's brain suggested the disruption is less severe in white tigers than it is in Siamese cats. Because of the visual pathway abnormality, by which some of the optic nerves are routed to the wrong side of the brain, white tigers have a problem with spatial orientation, and bump into things until they learn to compensate. Some tigers compensate by crossing their eyes. When the neurons pass from the retina to the brain and reach the optic chiasma, some cross and some do not, so that visual images are projected to the wrong hemisphere of the brain. White tigers cannot see as well as normal tigers and suffer from photophobia, like albinos.
Other genetic problems include shortened tendons of the forelegs, club foot, kidney problems, arched or crooked backbone and twisted neck. Reduced fertility and miscarriages, noted by ”tiger man” Kailash Sankhala in pure-Bengal white tigers were attributed to inbreeding depression. A condition known as "star-gazing", which is associated with inbreeding in big cats, has also been reported in white tigers. Some of the white tigers born to North American lines have bulldog faces with a snub nose, jutting jaw, domed head and wide-set eyes with an indentation between the eyes. However, some of these traits may be linked to poor diet rather than inbreeding.
There is a 450 lb (200 kg) male cross-eyed white tiger at the Pana'ewa Rainforest Zoo in Hawaii, which was donated to the zoo by Las Vegas magician Dirk Arthur. There is a picture of a white tiger which appears to be cross-eyed on just one side in Siegfried & Roy's book Mastering The Impossible. A white tiger, named Scarlett O'Hara, who was Tony's sister, was cross-eyed only on the right side.
A male white tiger named Cheytan, a son of Bhim and Sumita born at the Cincinnati Zoo, died at the San Antonio Zoo in 1992 from anaesthesia complications during root canal therapy. It appears that white tigers also react strangely to anaesthesia. The best drug for immobilizing a tiger is CI 744, but a few tigers, white ones in particular, undergo a re-sedation effect 24–36 hours later. This is due to their inability to produce normal tyrosinase, a trait they share with albinos, according to zoo veterinarian David Taylor. He treated a pair of white tigers from the Cincinnati Zoo at Fritz Wurm's safari park in Stukenbrock, Germany, for salmonella poisoning, which reacted strangely to the anaesthesia.
Mohini was checked for Chédiak-Higashi syndrome in 1960, but the results were inconclusive. This condition is similar to albino mutations and causes bluish lightening of the fur color, crossed eyes, and prolonged bleeding after surgery. Also, in the event of an injury, the blood is slow to coagulate. This condition has been observed in domestic cats, but there has never been a case of a white tiger having Chédiak-Higashi syndrome. There has been a single case of a white tiger having central retinal degeneration, reported from the Milwaukee County Zoo, which could be related to reduced pigmentation in the eye. The white tiger in question was a male named Mota on loan from the Cincinnati Zoo.
There is a myth that white tigers have an 80% infant mortality rate. However, the infant mortality rate for white tigers is no higher than it is for normal orange tigers bred in captivity. Cincinnati Zoo director Ed Maruska said: "We have not experienced premature death among our white tigers. Forty-two animals born in our collection are still alive. Mohan, a large white tiger, died just short of his 20th birthday, an enviable age for a male of any subspecies, since most males live shorter captive lives. Premature deaths in other collections may be artifacts of captive environmental conditions... In 52 births we had four stillbirths, one of which was an unexplained loss. We lost two additional cubs from viral pneumonia, which is not excessive. Without data from non-inbred tiger lines, it is difficult to determine whether this number is high or low with any degree of accuracy." Ed Maruska also addressed the issue of deformities: "Other than a case of hip dysplasia that occurred in a male white tiger, we have not encountered any other body deformities or any physiological or neurological disorders. Some of these reported maladies in mutant tigers in other collections may be a direct result of inbreeding or improper rearing management of tigers generally."
Inbreeding and outcrossing
Because of the extreme rarity of the white tiger allele in the wild, the breeding pool was limited to the small number of white tigers in captivity. According to Kailash Sankhala, the last white tiger ever seen in the wild was shot in 1958. Today there is a large number of white tigers in captivity. A white Amur tiger may have been born at Center Hill and has given rise to a strain of white Amur tigers. A man named Robert Baudy realized that his tigers had white genes when a tiger he sold to Marwell Zoo in England developed white spots, and bred them accordingly. The Lowry Park Zoo in Tampa Bay has four of these white Amur tigers, descended from Robert Baudy's stock.
It has also been possible to expand the white-gene pool by outcrossing white tigers with unrelated orange tigers and then using the cubs to produce more white tigers. The white tigers Ranjit, Bharat, Priya and Bhim were all outcrossed, in some instances to more than one tiger. Bharat was bred to an unrelated orange tiger named Jack from the San Francisco Zoo and had an orange daughter named Kanchana. Bharat and Priya were also bred with an unrelated orange tiger from Knoxville Zoo, and Ranjit was bred to this tiger's sister, also from Knoxville Zoo. Bhim fathered several litters with an unrelated orange tigress named Kimanthi at the Cincinnati Zoo. ankam Ranjeeth had several mates at the Omaha Zoo.
The last descendants of Bristol Zoo's white tigers were a group of orange tigers from outcrosses which were bought by a Pakistani senator and shipped to Pakistan. Rajiv, Pretoria Zoo's white tiger, who was born in the Cincinnati Zoo, was also outcrossed and sired at least two litters of orange cubs at Pretoria Zoo. Outcrossing is not necessarily done with the intent of producing more white cubs by resuming inbreeding further down the line.
Outcrossing is a way of bringing fresh blood into the white strain. The New Delhi Zoo loaned out white tigers to some of India's better zoos for outcrossing, and the government had to impose a whip to force zoos to return either the white tigers or their orange offspring.
Siegfried & Roy performed at least one outcross. In the mid-1980s they offered to work with the Indian government in the creation of a healthier strain of white tigers. The Indian government reportedly considered the offer; however, India had a moratorium on breeding white tigers after cubs were born at New Delhi Zoo with arched backs and clubbed feet, necessitating euthanasia. Siegfried & Roy have bred white tigers in collaboration with the Nashville Zoo.
Because of the inbreeding and resulting genetic defects the Association of Zoos and Aquariums barred member zoos from breeding white tigers, white lions and king cheetahs in a white paper adopted by the board of directors in July 2011. It is noteworthy that the first person to speak out against the displaying of white tigers was William Conway, director of the NY Zoological Association, which later became known as the Bronx zoo when he said, "White tigers are freaks. It's not the role of a zoo to show two headed calves and white tigers." He warned AZA in 1983 of the harm to the zoo's credibility in catering to the public's fascination with freaks, but went unheeded until 2008 when AZA issued a request to their members to stop breeding white tigers and then later in July 2011 when the AZA formally adopted that stance as policy. Conway was attacked by Ed Maruska of the Cincinnati Zoo for his observation, but in the end Conway's belief was validated.
White tigers appear frequently in literature, video games, television, and comic books. Such examples include the Swedish rock band Kent, which featured a white tiger on the cover of their best-selling album Vapen & ammunition in 2002. This was a tribute to the band's home town Eskilstuna, as the local zoo in town had white tigers from the Hawthorn Circus as its main attraction. The white tiger has also been featured in the video for the song "Human" by the popular American synth-rock band The Killers. White Tiger is also the name of an American glam metal band from the 1980s.
Aravind Adiga's novel The White Tiger won the Man Booker Prize in 2008. The central character and narrator refers to himself as "The White Tiger". It was a nickname given to him as a child to denote that he was unique in the "jungle" (his hometown), that he was smarter than the others.
Games including white tigers include Zoo Tycoon, the Warcraft universe, and Perfect World International. The popularity of white tigers has led private users to create mods or game patches for Elder Scrolls IV: Oblivion which changes the Khajit species to possess white tiger aspects, including realistic height and body sizes in relation to the standard orange Khajit. White Tigers are featured as a wild, tamable "pet" companion in Guild Wars Factions. White Tigers are also seen in Heroes of Might and Magic IV, where they are a level 2 unit for the nature alignment.
Both the Power Rangers and the Japanese Super Sentai series from which the Power Rangers series is based on, have used White Tiger themed mecha. A trained white tiger from the Bowmanville Zoo in Ontario, Canada, was used in the Animorphs TV series. A superhero named White Tiger appears in "The Justice Friends" on Dexter's Laboratory. Marvel Comics also publishes several superheroes who go by the name White Tiger. A white tiger named White Blaze is frequently shown in the anime Ronin Warriors. Tigatron from the animated TV series Transformers: Beast Wars is based on the white tiger. There have been at least 4 heroes in Marvel comics called "The White Tiger": two gained powers from a group of three mystic amulets that they possessed, one was actually a tigress evolved by the High Evolutionary, and one was given an artificial version of the "Black Panther's Heart Shaped Herb".
In Hayate the Combat Butler, Tama; Nagi Sanzenin's pet tiger is a white tiger.
Using white tigers in Circus and other propaganda campaigns often turn fatal. Most white tigers are sensitive to heat and noise. One of them used for election campaign in Lahore, Pakistan died of dehydration.
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