Tigers Can Change Their Stripes
Two white tigers, a black tiger and two typically patterned tigers. Left-to-right: A leucistic tigress, a leucistic pseudo melanistic tiger, a pseudo melanistic tiger, and two typically patterned tigers. Photo: Rajesh Kumar Mohapatura
A subpopulation of big cats with rare coloring shows evolution in action.
After sequencing the genomes of three zoo-born black tigers and their typical-coated parents, researchers at India's National Center for Biological Sciences and their colleagues tracked the pattern to a tiny change in a gene called taqpep.
Weebles-the-cat, pictured here sitting on my keyboard, has a classic tabby Mackerel pattern with stripes running parallel down her sides.
Altered taqpep genes were already known to cause blotched tabby patterns in cats, as well as king cheetahs' unusually large spots and stripes. But such large patterns are so rare because they occur only when genes from both parents have matching mutations.
A king cheetah with unusually large spots and stripes
The new study found that 10 out of the 12 Similipal tigers sampled had at least one copy of this particular taqpep change—and four were black tigers, with two copies each. But remarkably, not one of the 395 tigers surveyed outside the reserve had even one copy of the mutation. This suggests that the Similipal tigers are so isolated that they never breed with tigers outside that range and that the bgoup has begun to maintain genetic changes over generations. "It was an astonishing finding," remarks molecular ecologist and lead author Vinay Sagar.
A kitten with a blotched tabby pattern (swirls).