Nilgiris pale tiger an ‘aberrant genetic mutation’

The tiger, with white coat and dark stripes, which was spotted in the Nilgiris Biosphere Reserve .

The tiger, with white coat and dark stripes, which was spotted in the Nilgiris Biosphere Reserve .

While the pale tiger of the Nilgiris has won global attention, it could be just an instance of an aberrant genetic mutation, say experts.

“This is interesting because no pale tiger has been recorded in south India so far,” said Yadvendradev Jhala, wildlife scientist who heads the Department of Animal Ecology and Conservation Biology at the Wildlife Institute of India, Dehradun. “However, it is just a normal tiger with an aberrant genetic mutation, so it is not of great conservation value per se,” he said.

The Nilgiri Biosphere Reserve, where the pale tiger was photographed, also encompasses the Mudumalai-Bandipur-Nagarhole-Wayanad complex, which is home to the world’s largest wild tiger population. Random genetic mutations can occur in large populations and since this contiguous patch allows good intermixing of genes, this could just be a random genetic mutation as is natural in the wild, another genetics expert, who did not wish to be named, said.

It is quite possible that paler-looking tigers may occur rarely due to reduced levels of the pigment melanin in a phenomenon called leucism, says tiger expert K. Ullas Karanth. “Excess melanin causes black tigers, such as the ones in Simlipal in Odisha. However, with so many fake and modified photos/videos going around, I do not want to comment on this specific case as there is very little detail as to the time and place,” he added.

The ‘white’ gene

In 2013, scientists from China’s Peking University sequenced genomes (entire genetic material) of white and normally-colored Bengal tigers and found that a very small mutation in a single pigment gene – SLC45A2 – causes the white coloration. However, eumelanin pigments – which produce black and brown shades – are not affected, they showed, which explains the dark eyes and stripes of the tigers.

This genetic mutation was already known to cause light coloration in horses, chicken and fish. Concluding that such mutations were natural, especially since adult white tigers have been recorded in the wild in India in the past, the researchers say that white tigers could be viable in the wild and important for a healthy wild tiger population.

However, most white tigers may be at a disadvantage in the wild due to lack of camouflage, says Dr. Jhala.

All white tigers in captivity across the world trace their origins to one of the last white tigers in the wild, a male named Mohan with blue eyes and pink nose and paw-pads, which was captured from Rewa in Madhya Pradesh in 1951.

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Printable version | Aug 12, 2022 1:59:47 am | https://www.thehindu.com/sci-tech/energy-and-environment/pale-tiger-an-aberrant-genetic-mutation/article19235364.ece