Friday, September 25, 2015

The Story of White Tigers

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.

This is Kim. She is seven years old and was given to IEAS with her sister Karen by her previous caregiver. As you can see her left eye is severely crossed due to the strong defects associated with inbreeding.

 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

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