@natgeo: A rare genetic mutation called pseudo-melanism has resulted in roughly half of the tigers in India's Similipal Tiger Reserve sporting coats with far more black than those of usual tigers. This widespread coloration is a symptom of a shallow gene pool in a region that previously faced a dwindling tiger population, and could prove catastrophic if conservation officers aren't able to find these tigers more genetically diverse mates. Learn more about the causes of these black-coated tigers at the 🔗 in bio. #EarthDay