Indian tigers face threat 'due to lack of genetic diversity'

Tigers need genetic diversity to survive

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India's tigers are facing extinction owing to a collapse in the variety of their mating partners, say Cardiff University researchers. 

They found that 93% of DNA variants found in tigers shot the period of the British Raj were not present in tigers today

Prof Mike Bruford said the genetic diversity needed for the species to survive had been "lost dramatically". 

There are fewer than 2,000 tigers left worldwide, 60% in India. 

The Cardiff university team collaborated with the National Centre for Biological Sciences in Bangalore, India on the research. 

They had unprecedented access to the Natural History Museum of London's tiger collection which allowed them to identify the DNA variants in the tigers killed in the British Raj period from 1858 to 1947 but which have disappeared today. 

Mechanised trophy hunting reduced the animal's numbers from 40,000 in a mere 100 years. 

The territory occupied by the tiger has declined more than 50% during the last three generations and mating now only occurs in 7% of its historical territory. 

A tiger hunt on the back of elephants in India in 1912

Prof Bruford of the Cardiff School of Biosciences was one of the research's lead authors. 

He said: "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 (20-120 individual) populations that exist today. 

"This is due to loss of habitat and habitat fragmentation, meaning lower population sizes, and the prevention of tigers from dispersing as they once would have, which means their gene pool is no longer mixing across the subcontinent. 

Breeding programmes

"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." 

Prof Bruford added: "Both conservationists and the Indian government must appreciate that the number of tigers alone is not enough to ensure the species' survival." 

"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. 

"This study shows that genetic diversity can be lost and a new genetic structure can arise very quickly, if the effects of population collapse and habitat fragmentation are strong enough, so quick action is needed to stymie further demographic loss." 

The report Demographic loss, genetic structure and the conservation implications for Indian tigers is published in the Proceedings of The Royal Society journal. 

Funding for the project was provided by a Royal Society Collaborative Research Grant.