It is believed that white tigers are white because of the result of a genetic mutation which occurred about 120 years ago causing a pair of recessive genes to signal the coat to be chalk-white, the eyes ice-blue and the stripes chocolate coloured (I.W.B Thorton – 1978 – White tiger genetics – further evidence).
What the recessive genes did was to take the colour out of the tiger. The famous orange background colour of the coat became white which I deduce is due to a lack of pigmentation in the hairs of the coat. This is not white pigment but a lack of pigment i.e. melanin or phenomelanin. The eyes are ice-blue because, once again, they lack pigmentation in the irises. The blue colour is not because the irises contain blue pigment but because the light refracts in the eye causing the iris to take on the colour of a blue sky which is blue for the same reason i.e. white light refraction.
The stripes are no longer black or very dark brown but chocolate coloured. Once again this is due to a lack of pigmentation resulting in a dilution of the density of the colour.
White tigers are not albinos which would be a pure white tiger with pink eyes of which there are none I believe.
White tigers are extinct in the wild. They only exist in zoos to entertain people. They are all inbred and not purebred. This is because they are all descendants of a single male white cub captured in the forests of Rewa in Madhya Pradesh, India in 1951. The cub was named Mohan. His mother and four siblings had been shot by the Maharaja of Rewa. The Maharaja took the only white cub, Mohan.
When Mohan was mated with a normal coloured daughter, Radha (the offspring of an earlier mating by Mohan) a litter of four white cubs was born (I guess to the delight of the Maharaja). All captive white tigers are descended from this mating, which was a father mating with his daughter. That’s inbreeding and it has continued to occur in the world of white tigers ever since. White tigers can suffer from a range of inbreeding problems – inbreeding depression of the worst kind – which the public are increasingly aware of.
Zoos with white tigers are behaving unethically.
P.S. The reason why there is no pigment in the hair of white cats is because cells which are created very early on during the develop of the foetus inside the womb called melanoblasts – which turn into melanocytes (which are pigment producing cells) – do not migrate from their point of origin to the hair shaft. The point of origin of melanoblasts is the trunk neural crest cells.
The reason why this migration does not take place is because of genetic mutation referred. In these cats the migration is partly or completely halted.
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