While the country may be rejoicing that the numbers of tigers has stabilised in recent years, a recent international study says that the threat of inbreeding amongst the Indian tigers is being overlooked. It states that action must be taken to prevent “islands” of just a handful of tigers that are not connected to other populations.
The study titled “Demographic loss, genetic structure and conservation implications for Indian tigers,” is a joint effort between the scientists from the School of Biosciences in Cardiff University of Britain and the National Centre for Biological Sciences in Bangalore.
Researchers have found that genetic variation in the big cats has steadily declined to a mere seven per cent from 93 per cent about 100 years ago.
They have compared DNA samples of present day tigers to the genetic data of their counterparts from the British period when the animals were routinely hunted by British officials and Indian royalty.
The historic samples and genetic material of the latter have been obtained from the Natural History Museum in london and National Museum of Scotland in Edinburgh. The study has found that in modern tigers there is lesser genetic mingling than their predecessors.
The warning has come at a time when the tiger count in the country is on an upswing. As per the last tiger census figures of 2010, the tiger count of the country is 1,706. This is an increase of 295 tigers from the 2006 tiger estimate of 1,411.
According to an assessment made by scientists at the Wildlife Institute of India, tiger reserves as Ranthambore, Corbett, Dudhwa, Bandipur and Mudumalai are already brimming with big cat population (with density varying from 12-17 tigers/ 100 sq km).
The study points out that this is just one side of the story. Simple numbers are not enough to ensure the survival of the species. lack of genetic diversity amongst Indian tigers is one of the major threats to their population today.
In the past there were two broad naturally occurring groups of tigers that had genetically distinct traits. One was categorised as the peninsular India group while the other was called Terai-Semi Arid region group. There were genetic connections between the tigers from these two areas. But now there is distinct disconnect, due to both loss and fragmentation of habitats.
“Such disconnect is a conservation red flag. It is a pointer to the fact that simply increasing the number of tigers, say in Ranthambore, will not help,” pointed out Uma Ramakrishnan, a biologist at NCBS who was a part of the study.
Tigers, like all other species, need genetic diversity to survive, especially under climate change. Hence, whatever genetic diversity remains, about seven per cent, needs to be managed properly so that the Indian tiger does not become inbred, and retains its capacity to adapt. Such disconnect signatures were shown by other large animals in the past before extinction,” he added.
The experts pointed out that this genetic crisis is due to loss of habitat and fragmentation.
“This means lower population sizes, and the prevention of tigers from dispersing as they once would have, indicating that their gene pool is no longer mixing across the subcontinent.”
The new study is thus aimed at providing a scientific pedestal to plan out conservation strategies.
“Increasing connectivity, by working on the corridors between forest landscapes is crucial in securing the future of the tigers”, said the experts.
The idea is to conserve the landscape along with the reserves that have their own unique gene combinations, which might be useful for future breeding programmes, they added.