White Tiger

    The white tiger is a pigmentation variant of the Bengal tiger, which is reported in the wild from time to time in States of India like Assam, Bengal, Bihar,Sunderbans and especially in the former State of Rewa. The White Bengal tigers are distinctive for their color fur. According to the website, “Animal Corner,” the correct term to name the white tiger is Chinchilla albinistic. The white fur is due to the lack of pheomelanin pigment, which is found in Bengal tigers with orange color fur. When compared to Bengal tigers, the white Bengal tigers tend to grow faster and heavier than the orange Bengal tiger. They also tend to be somewhat bigger at birth, and as fully grown adults. White Bengal tigers are fully grown when they are 2–3 years of age. White male tigers reach weights of 200 to 230 kilograms and up to 3 meters in length. Similar to zebras, the white Bengal tiger’s stripes are like fingerprints, no two tigers have the same. Also, the stripes of the tiger are a pigmentation of the skin. For a white Bengal tiger to be born, both parents must carry the unusual gene for white colouring, which, according to the website “Animal Corner,” only happens naturally about once in 10,000 births. As stated by Kailash Sankhala, the director of the New Delhi Zoo in the 1960s, “one of the functions of the white gene tiger 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)[citation needed], as well as having been reported historically in several other subspecies.

     A white tiger's pale coloration is due to the lack of the red and yellow pigments that normally produce the orange color. 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.[citation needed] 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.

Sources :
en.wikipedia.org (article & image)
7-themes.com (image)