In News:

• Odisha government relocated a tigress from Maharashtra’s Tadoba-Andhari Tiger Reserve to Similipal Tiger Reserve, Odisha, to address inbreeding issues among the tiger population.
• The tigress is part of a genetic diversification plan to remedy the increasing number of pseudo-melanistic tigers in the region.

Pseudo-melanistic Tigers:

• Pseudo-melanistic tigers, often referred to as "black tigers," exhibit a darker coat with broader, more prominent stripes.
• The mutation leads to the appearance of a mostly black fur, with occasional white-orange stripes.

Genetic Basis:

• This coloration is due to a mutation in the Taqpep gene, which causes the widening and darkening of stripes on the tiger's coat.
• The mutation is linked to genetic drift and inbreeding within the isolated Similipal population.

Historical Context:

• These tigers were once considered mythical until the 1700s, with sightings only being documented in the 1990s and 2017-18.
• The first confirmed genetic evidence of the black tiger appeared when a cub was born in captivity at Oklahoma City Zoo in the 1970s.

Distribution and Prevalence:

• Pseudo-melanistic tigers are predominantly found in Similipal Tiger Reserve, with 27 out of 30 tigers in Odisha exhibiting the trait.
• Other instances of such tigers exist in captivity, such as in Nandankanan Zoological Park (Bhubaneswar) and Arignar Anna Zoological Park (Chennai), both tracing ancestry to Similipal.

Genetic Studies:

• A 2021 study by the National Centre for Biological Sciences (NCBS) linked the Taqpep gene mutation to the unique appearance of these tigers.
• The mutation causes a missense change in the gene, replacing Cytosine with Thymine (C1360T), altering the tiger’s coat pattern.

High Frequency of Mutation in Similipal:

• Genetic analyses indicate a high frequency of the Taqpep gene mutation in Similipal tigers, with a 60% chance that a tiger born there will carry the mutated gene.
• Inbreeding and genetic isolation have contributed to this phenomenon, as Similipal’s tiger population is geographically cut off from other populations.