India, Nov. 14 -- 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? 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. 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. In a DNA sequence, an individual carries two copies of the genetic material - one from the mother, one from father. If one get damaged, the DNA uses the other copy. If the DNA has both damaged copies (from related parents), this can cause genetic defects in the offspring. This is the reason genetic inbreeding can cause mutations. Not all genetic mutations are bad, says Ramakrishnan. Some, like eye colour, are pretty harmless "Even the black coat in Similipal tigers is not bad per se, but it suggests that the population is isolated and inbreeding," she says, adding that she's found the same inbreeding signals in tigers of Ranthambore. Such inbreeding depression, where close relatives mate and the same mutation spreads in a population leads to lower reproduction and survival chances. In 1990s, scientists in California for example, found that due to genetic depression, the threatened population of Florida panthers in California were developing mutations that led to heart defects and kinked tails. At that time, the panther population was at a mere 30 individuals. In 1995, scientists introduced panthers from Texas (a subspecies) to try and save the wild population in California. Thirty years later, in 2025, scientists at UCLA and UC Berkeley studied the same Florida panther individuals and found that adding genetic variation reduced the influence of harmful mutations and improved the species' fitness. The Florida panthers - now at 200-odd individuals - are healthier thanks to the immigrants introduced to their inbreeding population, according to the study that was published in the National Academy of Science journal in July 2025. Though studying genetic variations in small wild population helps protect and conserve them, the scientists also cautioned against using genetic rescue as a strategy as the wildlife behaves in ways that can be unpredictable for humans. "The effects of translocating individuals can be highly variable and subject to change, especially looking into the future," explains Dr Kirk Lohmueller, a professor of ecology and evolutionary biology at UCLA, adding that constant monitoring is essential. Before you try an intervention, you need to know a lot about the species but even with that information, introducing new individuals to the population can lead to unexpected results, explains Dr VV Robin, associate professor at Indian Institute of Science Education and Research, Tirupati, who studies evolutionary ecology in birds. Tigers are the most studied wild animals in India and we know a lot about this species. Multiple labs and scientists have looked at them, but that's not true for many other species. "Species of birds I study are impacted by climate change rather than isolation," says Robin, "so I try to understand evolutionary mechanism and how species adapt to climate change." DNA intervention is a useful tool but scientists need a lot of genomics data to understand which intervention to apply to which species and when. Pre Covid-19, using DNA interventions was difficult and expensive. Thanks to newer technologies, studying evolution and population through genetics of wild animals has become more accessible to ecologists than a couple of decades ago. Even collection of data is becoming easier, Ramakrishnan explains. She started mapping tiger genomes using blood, moved on the faecal and hair samples picked up on forest trails and now is currently collecting data of individual tigers from trophies of dead tigers from across the world. "With modern tools of next-generation sequencing, it is possible to generate high-quality genetic data," says Dr Karthikeyan Vasudevan, chief scientist, Centre for Cellular and Molecular Biology. Vasudevan studies gharials through genomics. His paper on the gharials of Chambal, published late last year, concluded that in spite of challenges like hunting, the wild population had enough genetic diversity. "In Chambal, we're fortunate to have a large wild population of gharials with reasonable amount of genetic diversity, but we don't know about fragmented populations in other sanctuaries," he says, adding that these populations need to be studied genetically too to flag any isolation or genetic depression. A few years ago, setting up a genomics lab was expensive, but today, it takes under Rs.50 lakh to set up and about Rs.20-40 lakh per year to run a lab. In spite of this, there are just a handful of labs studying genomics of wildlife. It's more than just grants, explains Robin. "Getting genetic samples from our forests is not easy, thanks to our colonial legacy on how we access wild animals," he says, adding that he knows of scientists who stopped working on species as getting forest permits was a constant tussle. The other challenge remains dedicated students with skills in the constantly changing genetics technology. Robin actively goes to rural colleges to encourage more students to work in his laboratory. In India, genomics still remains in the traditional biology space - studying genes of humans, lab rats and fruit flies in a lab. Very few biologists are interested in studying wildlife. "This is the right time for us to understand how wild animals recover from population crashes and develop genetic resilience," says Ramakrishnan, urging more geneticists to get away from controlled lab studies into studying wildlife....