Changing stripes: How genomics can reshape wildlife conservation

A combined effort of scientists and the Odisha forest department has just saved Similipal’s tigers from inbreeding depression. Is genetic rescue a new way to conserve wildlife?

- Shweta Taneja

A few years ago, the elusive tigers of Similipal Tiger Reserve in Odisha started to change their stripes. The coat on their backs became darker, a condition locals call a black tiger and scientists call pseudo-melanism.

To try and understand what was happening, the forest department brought in Dr Uma Ramakrishnan, a molecular ecologist at National Centre for Biological Sciences who specialises in the wild population of tigers. Ramakrishnan collected faecal samples of tigers in the reserve, ran tests on them, and found the anomaly: A mutation in a particular gene (Transmembrane Aminopeptidase Q) thanks to inbreeding depression (the scientific term for reduced biological fitness). “The fact that in Similipal 60% of the tigers could have this mutation meant that the population is isolated and mating is happening between aunts and nephews,” Ramakrishnan says.

If no action was taken, the genetic isolation would increase, leaving the tigers in Similipal infertile, diseased or even extinct within a few decades. The Odisha forest department used Ramakrishnan’s findings to introduce two tigresses from Tadoba Tiger Reserve into Similipal—an action called genetic rescue. “Understanding conservation priorities through genes, an area called conservation genomics, is fast becoming a hot area of research,” says Ramakrishnan.

Science behind genetic rescue

Like Similipal’s tigers, wildlife across the world have become fragmented, leading to inbreeding and reduced genetic diversity among local populations ~ which remains an ongoing conservation concern. It’s hard for isolated population to mate with others, leading to nephews mating aunts and even closer relatives like sisters mating fathers.