White Tiger Against Siberian Tiger

Compared to orange tigers without the white gene, white tigers tend to be larger both at birth and at full adult size. This may have given them an advantage in the wild despite their unusual coloration. Heterozygous orange tigers also tend to be larger than other orange tigers. 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. White pelage is most closely associated with the Bengal, or Indian subspecies. Currently, several hundred white tigers are in captivity worldwide with about 100 of them in India, and their numbers are on the increase. The modern population includes both pure Bengals and hybrid Bengal–Siberians, but it is unclear whether the recessive gene for white came only from Bengals, or from any of the Siberian ancestors as well.