The Story of a White Tiger:
This is Kumar. He is an eleven year old white tiger who was brought here with his two siblings from another facility so that they could avoid licensing issues. |
White tigers only exist in captivity as a result of
inbreeding, which produces a double recessive gene. The white coloration is
caused by a mutation in the SLC45A2 gene, restricting the expression of red and
yellow pigments.
The inbreeding of tigers began in 1951 with Mohan, who was
captured from the wild in India, raised and inbred to his daughter leading to
the existing population of captive white tigers. The recessive mutation was
then discovered to be present in both male Siberian tigers and female Bengal
tigers. As a result in the 1970’s many small zoos began breeding these two
species to give rise to white tigers.
However, many white tigers suffer from
genetic disabilities including: crossed eyes, spinal problems, deformed
kidneys, cleft palate, as well as club footedness. For example, Kim and Kumar at
IEAS both have crossed eyes, which are the result of inbreeding that causes
the optic nerve to connect to the opposite side of the brain.
Some
studies suggest that white tigers can survive in the wild, considering they
were found in the wild since the 1500’s, but the last white tiger to be found
in the wild was shot in 1958. On the other hand, deleterious mutations such as
those found in white tigers are highly disadvantageous for survival in the wild
considering they do not blend in well in a tropical jungle environment causing them to be killed off. White tigers are also reported to live shorter lives due to their genetic complications, presuming they aren't rejected by their mothers and survive the birthing process.
In June 2011 the AZA banned the breeding of white tigers,
white lions, or king cheetahs and other species that express rare genetic
traits due to the high correlation to debilitating genetic and physical issues.
Therefore, the nine white tigers at IEAS are advocates for their species as
their stories help to educate the public on how natural selection occurs and
the large downstream effects that it can have on a population