KOMPAS.com – Visiting the Similipal Tiger Sanctuary in East India is an unusual sight.

Tigers, which usually have orange fur, actually show more black stripes.

So far, no one knew why this could happen. But now a team of Indian and American geneticists have identified the cause of the oddity.

Citing Gizmodo, Wednesday (9/15/2021), researchers found that the tigers were pseudomelanistic, meaning they have wide stripes that converge along their bodies.

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From different angles, pseudomelanistic tigers also look black, hence the nickname black tiger.

To find the cause, the study, led by Vinay Sagar of the Tata Institute of Fundamental Research, then performed a genetic test on 85 tigers, which are made up of four subspecies.

The team’s analysis revealed that the pseudomelanistic tigers all had single nucleotide variants in their genetic code that appeared to alter certain genes.

This gene is called transmembrane aminopeptidase Q (Taqpep for short), and it is the same gene that is responsible for the pattern of spots and stripes in cats and cheetahs.

“Pseudomelanistic tigers have a mutation in their taqpep gene. And without that gene, the patterning process breaks down, causing enlargement and occasional streaking,” said Greg Barsh, a geneticist at Stanford University.

Then why can pseudomelanism occur in tigers? One theory is that it was triggered by inbreeding in the tiger population.

But researchers have a different opinion. It could have happened because of some evolutionary advantage.

An example of this is the melanistic leopard. These tigers are more common in dark, dense tropical forests than in drier, open environments.

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Had the situation been similar, the tiger might have lost some of its orange color to better blend in with the forest vegetation.

“Most color mutations tend to affect the whole body, like albinism or melanism. So mutations that affect color patterns are very interesting from a scientific point of view as they help us understand more about developmental biology, ”said Barsh.

These results were published in Proceedings of the National Academy of Sciences.

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