Mystery of ‘black tigers’

The abnormally dark or black coat in such tigers is termed pseudomelanistic

New Delhi: The enduring mystery behind the ‘black tigers’ of Similipal in Odisha may finally have been solved with researchers identifying a single mutation in a gene that causes their distinctive stripes to broaden and spread into their tawny pelt, occasionally appearing entirely dark.

Considered mythical for centuries, the ‘black tigers’ have long been a subject of fascination. Now, a team led by ecologist Uma Ramakrishnan and her student Vinay Sagar from the National Centre for Biological Sciences (NCBS), Bengaluru, have discovered that the coat colouration and patterning which make the wild cats appear dark boil down to a single mutation in the Transmembrane Aminopeptidase Q (Taqpep) gene.

---

The researchers combined genetic analyses of other tiger populations from India and data from computer simulations to show that the Similipal black tigers may have risen from a very small founding population of tigers and are inbred — providing an answer to the question that had perplexed so many for so long.

The study, published in the journal Proceedings of the National Academy of Sciences on Monday, noted that tigers in the Similipal Tiger Reserve are an isolated population in eastern India, and gene flow between them and other tiger populations is very restricted.
The researchers noted that this has important implications for tiger conservation as such isolated and inbred populations are prone to extinction over even short periods of time.

The abnormally dark or black coat in such tigers is termed pseudomelanistic or false coloured. The most recent sightings of this rare mutant tiger in Similipal, long considered mythical, was reported in 2017 and 2018.

Since the late 1700s, reports of black tiger sightings and supposed captures in central and northeast India have been recorded by locals and British hunters.
Photos captured from Similipal in 2018 showed eight unique individuals, three of which were ‘pseudomelanistic’ tigers, characterised by wide, merged stripes.