White tiger
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[Photo] Singapore Zoological Gardens White Tigers. Date 14th September 2005. Author Nachoman-au http://commons.wikimedia.org/wiki/User:Nachoman-au

White tigers are Bengal tigers (Panthera tigris tigris) or tigers of mixed Bengal/Amur ancestry with pink noses, white-to-creme coloured fur and black, grey or chocolate-coloured stripes. Their eyes are usually blue, but may be green or amber. There are several hundred captive white tigers worldwide (this number increases annually), all of whom can trace their ancestry back to a single white Bengal tiger caught in Rewa, India.

White tigers are formed exclusively from inbreeding- usually between parents and cubs. Though such inbreeding often leads to birth defects, the wide appeal of the White Tiger has lead to inbreeding as a regular practice.

Due to the opinion that their colouration is widely considered striking, white tigers have become popular attractions in zoos and entertainment that showcases exotic animals; the magicians Siegfried and Roy are famous for using several trained white tigers in their shows. Contrary to popular belief, white tigers are not a separate species in their own right, but are a mutant form of the orange Bengal tigers.

White Bengal and White Amur Tigers
The tigers' colour is caused by a recessive gene. The gene for white colouration is usually associated with Bengal tigers. It is an extremely rare animal in the cat family. It is hunted for its fur by many poachers and hunters even though it’s illegal.

White tigers may have occurred in the Amur or Siberian tiger subspecies. Two registered pure-bred Amur brothers conceived at the Como Zoo may have carried the white gene (their most famous descendant being Tony, a founder of many American white tiger lineages). Their wild-caught parents were pure Amur tigers although one of these has also been described as a Bengal/Amur hybrid. These white Amur tigers have since been interbred with white Bengal tigers as well as leaving pure-bred Amur offspring. In addition to white generic tigers and white Bengal tigers, there are also purebred white Amur tigers in existence. Most white tigers bred in captivity are generic tigers, that is, a hybrid of two subspecies ??? most commonly, a mix of Bengal and Siberian ancestry.

Mohan
Mohan is the founding father of white Bengal tigers. He was captured as a cub in 1951 when Maharajah Shri Martand Singh and his hunting party found a tigress with four 9 month old cubs, including one white one, while hunting in Bandhavgarh. All but the white cub were shot. The white cub was later captured and housed at the Maharajah's palace. He named it Mohan, meaning "Enchanter".

In 1952, Mohan was bred to a normal-coloured wild tigress called Begum, but they produced only orange cubs because Begum did not carry the recessive white gene. Some of these cubs, which carried the white gene, were sent to zoos and, as a result, white tiger cubs have been born unexpectedly to orange parents in zoos. Mohan was then bred to his daughter Radha (who carried the white gene) and they produced a number of white cubs, including Mohini ("Enchantress") who later founded American lines of white tigers. Mohan died in 1969, aged almost 20. He was the last recorded wild-caught white tiger.

Mohini
Mohini, a descendent of Mohan, was officially presented to President Eisenhower on the White House lawn in 1960 and went to live at the Washington Zoo. She was a great attraction and the zoo wanted to breed more white tigers. At the time, no more white tigers were being allowed out of India so Mohini was mated to Sampson, her mother's normal colored brother and to her own normal-colored half-brother. Mohini was then bred to her own male offspring who carried the white gene. This resulted in the coveted white tigers and they were traded with other zoos in the USA.

Tony
Tony, born in 1973, was the founder of many American white tigers, especially of white tigers used in circuses. His grandfather was a registered Amur tiger who was bred to a Bengal tigress. Two of their cubs (Rajah and Sheba II) were bred together in a brother-sister mating and one of the results was Tony. Tony therefore carries mixed blood and was responsible for introducing Amur genes into previously pure Bengal lines in North America. He may also be the source of a gene for stripelessness.

Orissa White Tigers
White tigers also appeared in the Nandankanan Zoo in Orissa, India. Three white tiger cubs were born there in 1980. Their parents were normal-colored tigers called Deepak and Ganga who were not related to Mohan or to any of the white tigers being bred in zoos. One of their wild-caught ancestors would have carried the recessive white gene. It showed up when Deepak was mated to his daughter Ganga. This lineage resulted in several white tigers in Nandankanan Zoo and in Sri

Stripeless (Snow White) Tigers
Pure white non-albino tigers have been reported. One was exhibited at Exeter Change in England in 1820 and described by Cuvier, Lydekker and Hamilton Smith and drawn by Landseer in 1824. Stage magicians Siegfried and Roy also own snow white tigers and were the first to attempt to breed selectively for stripelessness. Their current snow white Bengal tigers come from Cincinnati Zoo and from Guadalajara, Mexico. They also have a stripeless Amur tiger called Apollo.

The modern strain of snow white tigers came from repeated brother-sister matings of Bhim and Sumita at Cincinnati zoo. The gene involved possibly came from the Amur tiger via their part-Amur ancestor Tony. Continued inbreeding appears to have caused a recessive gene for stripelessness to show up. About 25% of Bhim and Sumita's offspring were stripeless. Their striped white offspring have been sold to zoos around the world, but may carry the stripeless gene. Because Tony is present in many white tiger pedigrees, the gene may also be present in many other captive white tigers. As a result, stripeless tigers have occurred in zoos as far afield as the Czech Republic, Spain and Mexico.

Genetics
Contrary to popular belief, white tigers are not albino; true albino tigers would have no stripes. Since "white tigers" are not actually pure white, they are sometimes called chinchilla tigers in order to avoid confusion. Other names are ice tigers referring to their frosty appearance and not to their habitat. There is no evidence of true albinism in modern tigers; to date, all so-called "albino tigers" have so far been chinchilla tigers with unusually pale stripes. Part of the confusion is due to the misidentification of the chinchilla gene as an allele of the albino series (publications prior to the 1980s refer to it as an albino gene). The mutation is recessive to normal color which means that two normal colour tigers carrying the mutant gene may produce white offspring; however two white tigers will produce only white cubs when bred together.

In tigers, the chinchilla (color inhibitor) gene is recessive to the normal orange color. When two copies of the color inhibitor are inherited, this results in a white tiger. Tigers with only one copy of the gene are normal colour, but can pass on the color inhibitor gene to their offspring. Two normal color tigers that both carry the color inhibitor gene can therefore have white offspring. The stripe color varies due to the influence and interaction of other genes.

The wide band gene affects the amount of colour on the hair shaft. When two copies of wide band are inherited by a white tiger, this results in stripeless or almost stripeless white tigers (when two copies of wide band are inherited by an orange tiger this results in the golden tabby tiger). Inbreeding allows the effect of recessive genes to show up hence the variability in ground colour and stripe colour of white tigers.

Lydekker (1907) doubted the existence of albino tigers. However, true albino tigers were later recorded in 1922 at Mica Camp, Tisri in the Indian state of Cooch Behar when two pink-eyed albino young tigers were shot along with their mother. This was reported by Victor N Narayan in a Miscellaneous Note in the Journal of the Bombay Natural History Society. A tawny tigress who was shot along with 2 colored and 2 sickly-looking white cubs (sub-adults) that had extended necks and pink eyes.

A pure white tiger was described in the 1800s as showing ghost stripes. This tigress had stripes that were visible only at certain angles of reflection. "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 described by Hamilton Smith". Baron Georges Cuvier described the same tigress in his book Animal Kingdom: "A white variety of Tiger is sometimes seen, with the stripes very opaque, and not to be observed except in certain angles of light." In The Royal Natural History, Richard Lydekker described it as "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."

Stripeless white tiger cubs occurred at Cincinnati Zoo, but were believed to be sterile. A stripeless female was obtained from the zoo by Siegfried and Roy and was successfully used in breeding. Siegfried and Roy's snow white tigers Tsumura, Mantra, Mirage, and Akbar-Kabul were born at Cincinnati Zoo and sired by Bhim. Their snow white tigers Vishnu and Jahan were born in Guadalajara, Mexico. Apollo is their snow-white Amur tiger. In 2004 a blue-eyed, stripeless white tiger was born at a wildlife refuge in Alicante, Spain. Its parents are normal orange Bengal tigers. The cub was named Artico (Spanish for Arctic). None of the pure white tigers currently in captivity are albinos.

White tigers have always been extremely rare in the wild. Since Mohan's capture, there have been no further confirmed sightings, although zoologists believe that the gene may still be found in certain wild Bengal tiger populations.

Inbreeding depression
??? Because of the extreme rarity of the white tiger allele in the wild, the breeding pool is limited to the small number of white tigers in captivity, which additionally all descend from a common ancestor. Inbreeding between these tigers often leads to defects. Due to the high market value for white tigers, unscrupulous breeders will still inbreed white tigers to ensure the offspring also exhibit the recessive gene. Some animal rights activists have called for a halt to the breeding of white tigers altogether.

Outside of India, highly inbred white tigers are prone to cross eyes (strabismus) due to incorrectly routed visual pathways in the brain, star-gazing and postural problems, a weakened immune system and poor tolerance of anesthesia, possibly due to inability to synthesize the tyrosinase enzyme. Strabismus is associated with white tigers of Bengal/Amur ancestry. Only one pure Bengal white tiger was reported to be cross eyed, this being Mohini's daughter Rewati.

White tigers may also be prone to Chediak-Higashi Syndrome which causes bluish lightening of the fur color and is associated with crossed eyes. Other genetic problems include shortened tendons of the forelegs, clubbed feet, central retinal degeneration, abnormal kidneys, arched or crooked backbone and twisted neck. Reduced fertility and miscarriages were noted by Sankhala and were attributed to inbreeding depression. 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 have also been linked to poor diet.

Historical records
White tigers have been recorded outside of the Indian state of Rewa and as far afield as China and Korea and from Nepal, Myanmar, the Malay Peninsula, Sumatra, and Java. Historically, white tigers have been reported in northern China, in the geographic range of the Amur tiger (previously called the Manchurian/North China tiger and the Siberian tiger) and in the Indo-Chinese, Sumatran and Javan subspecies. White tigers have not been reported amongst the South China, Caspian or Bali tigers.

White tigers form part of tradition in some regions. In China, the white tiger was revered as the god of the West, Baihu. The white tiger is represented on the South Korean flag in the Yin and Yang emblem, the white tiger as evil opposite of the green dragon for good. According to Indian superstition, the slayer of a white tiger would die within a year and the white tiger was regarded as the incarnation of a Hindu god. Sumatran and Javan royalty claimed descent from white tigers, and white tigers were regarded as the reincarnations of royalty.

White tigers with dark brown or reddish-black stripes were recorded in the wild during the Mughal Period from 1556 - 1605 AD. A painting from 1590 of Akbar hunting tigers near Gwalior depicts 4 tigers, 2 of which appear white. As many as 17 instances of white tigers were recorded in India between 1907 and 1933 in several separate locations: Orissa, Bilaspur, Sohagpur and Rewa.

One of the earliest records of white tigers is of one displayed in London in 1820 and described by Rev. J G Woods as "a creamy white, with the ordinary tigerine stripes so faintly marked that they were only visible in certain lights". White tigers were routinely shot between 1892 and 1922 in places such as Orissa, Upper Assam, Bilaspur, Cooch Behar and Poona. Pollock (1900) reported white tigers from Burma, the Jynteah hills of Meghalaya, between the 1920s and 1930s 15 white tigers were killed in the Bihar region, and more were shot in other regions. Some of the trophies exhibited in Calcutta Museum. In 1922, two pure white young adult tigers with pink eyes were shot in Cooch Behar (northeast India). At Mica Camp, Tisri in Behar. On 22 January 1939, the Prime Minister of Nepal shot a white tiger at Barda camp in Terai Nepal. In 1951, a normal colored tigress and cubs were shot, but her white cub was captured alive some days later. This cub "Mohan" is ancestral to most modern white tigers. The last observed wild white tiger was shot in 1958 and the mutation is considered extinct in the wild. The slaughter of hundreds of orange tigers evidently killed the carriers of the mutant gene.

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