Explanation:

Researchers from the National Centre for Biological Sciences (NCBS) have zeroed in on a rare mutation that results in large, merged stripes that cause the tiger to appear black in Similipal Tiger Reserve (STR).

The rare mutation behind this has been found in Transmembrane Aminopeptidase Q or Taqpep gene. The main cause of the rare mutation is genetic drift. Due to this geographic isolation, genetically related individuals have been mating with each other for many generations in Similipal, leading to inbreeding. The Similipal Tiger Reserve (STR) is the only tiger habitat in the world with melanistic tigers, which have broad black stripes running across their bodies and are thicker than those seen on normal tigers.