Indian tigers face extinction due to inbreeding and 'lack of genetic diversity'

Scientists say the current population has just seven per cent of the total DNA that existed within the community during British Raj

India’s population of tigers, which once surpassed 100,000 animals, is facing extinction because of a collapse in the variety of mating partners, according to new research.

Scientists say the current population of tigers has just seven per cent of the total DNA that existed within the community at the time of the British empire, when the animals were routinely hunted by British officials and Indian royalty.

The experts say that while India’s dwindling numbers of tigers may have stabilised in recent years, the threat of inbreeding is being overlooked and that action must be taken to prevent “islands” of just a handful of tigers that are not connected to other populations.

“A lot of the diversity has gone because the population has collapsed as a result of the threat to habitat,” said Professor Mike Buford of the School of Biosciences at Britain’s Cardiff University.

“What genetic diversity is left only exists in pockets. The Indian government is saying things are reasonably all right because the population has stabilised. But we are saying that is only part of the story.”

At the turn of the 20th Century, India was home to an estimated 100,000 of the animals. As a result of hunting, illegal poaching and declining habitats, that number now stands at fewer than 2,000.

Scientists from Britain, in collaboration National Centre for Biological Sciences in Bangalore, were able to compare genetic data from modern tigers with that of animals shot during the time of the British Raj. Those animals are part of the London Natural History Museum tiger collection.

The researchers found a high number of DNA variants in the tigers shot more than a 100 years ago and that up to 93 per cent of the that diversity missing in today’s creatures.

“We found that genetic diversity has been lost dramatically compared to the Raj tigers and what diversity remains has become much more subdivided into the small populations that exist today,” said Mr Bruford.

He added: “This is important because tigers, like all other species, need genetic diversity to survive - especially under climate change – so what diversity remains needs to be managed properly so that the Indian tiger does not become inbred, and retains its capacity to adapt.”

The latest census of tigers in India, carried out in 2011, suggested the total population may stand at around 1,700, a figure that would represent a stabilisation or even a slight increase on previous counts.

However, not all experts trust that figure, pointing out that the survey was done using camera traps and extrapolation rather than pug mark counts, as has been previously used.

Valmik Thapar, a leading Indian tiger expert, said he believed the biggest challenge to the nation’s big cats was a lack of political leadership and poor governance.

He said the idea of the establishment of “corridors” for the tigers that joined up various populations, would never happen. “We don’t have the political will or the governance,” he told The Independent.

The Cardiff scientists, whose work is published in the Proceedings of The Royal Society B journal, said the territory occupied by the tiger has declined more than 50 per cent during the last three generations and that today mating only occurs in 7 per cent of its historical territory.

India accounts for perhaps 60 per cent of the world’s tigers. Yet everywhere they are under threat and over the past century total numbers have fallen by 95 per cent.

Of the nine sub-species of tiger, three – the Caspian, Javanese and Balinese – are already lost. A fourth, the South China tiger, is considered “functionally extinct” with perhaps fewer than 30 surviving in the wild, and the the Sumatran tiger is listed as critically endangered.

The others – the Indochinese, the Malayan, the Siberian and India’s Bengal tiger, are all facing hue threats.

“Both conservationists and the Indian Government must appreciate that the number of tigers alone is not enough to ensure the species’ survival,” said Mr Bruford.

“They need to protect the whole spread of forest reserves because many reserves now have their own unique gene combinations, which might be useful for future breeding programmes.”

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