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Current Affairs

Black tiger

Date: 20 September 2021 Tags: Biodiversity

Issue

Scientists have been successful in solving the mystery of Simlipal’s Black Tigers. This issue was one of the major genetic mysteries that had remained a question.

 

Details

The black stripes broadened and the black colour spread to the background due to a genetic mutation in these tigers.

 

The genetic variations

  • A rare pattern variant is observed in both wild and captive populations. This includes stripes that are broadened and fused together.

  • This condition has been named as pseudo-melanism. It is different from true melanism in which a dark pigment is deposited all over the skin.

  • In general conditions, tigers usually have a dark black pattern or stripes over light background of white or golden. 

  • The researchers were able to find that pseudo-melanism was through a mutation in Transmembrane Aminopeptidase Q (Taqpep).

 

Black Tigers

A completely true melanistic tiger is yet to be found but pseudo-melanism conditions have been seen in tigers only in Simlipal Tiger Reserve.

 

Why rare?

  • Genetic mutations occur simultaneously but are rare. Since 1773, black tiger claims were made from Myanmar and China.

  • The black tigers were considered novelty by trophy hunters and very few survived to establish their bloodlines.

  • For a tiger cub to be born with pseudo melanistic characteristics, two tigers having normal pattern with recessive genes have to breed. Since it is a recessive gene, only one in four cubs may have such characteristics.

 

Conditions for occurrence of black tigers

  • Such conditions do not occur in ideal circumstances where there is a large population for mating. It takes place in small populations that is forced to inbreed in isolation for generations.

  • Such conditions may have occurred in Simlipal, where recessive genes get opportunity to be expressed more often than not.

 

Why Simlipal?

The nearest breeding tiger population to Simlipal is around 800 km away. This is greater than average dispersal distance (78-124 km) and average home range (20-110 km) of Bengal tigers.