Indian tigers face extinction due to lost genetic diversity
Over the last two centuries, Indian tigers have become more vulnerable for extinction due to isolation of big cat population triggered by loss of habitat, population biologists in Bangalore have claimed.
Notwithstanding a rise in their absolute numbers in the last seven years, physical isolation of big cats in Terai population in the jungles of the east and semi-arid zones of the west such as Ranthambhore and Sariska, have made them vulnerable because the animals lost their genetic diversity. They are now two genetically isolated groups, which do not have enough resilience and can easily come under threats from nature. Though wildlife scientists are aware of such threats, the new study provided a scientific pedestal to plan out conservation strategies. Increasing linkage, they say, between forest landscapes is the only to secure the future of the striped cats.
In the past there were two broad naturally occurring groups of tigers that had genetically distinct characteristics. One group was categorised as peninsular India group while the other was called Terai-Semi Arid region group as there were genetic connections between the animals from these two areas. Now, there is a separation.
“The disconnect is a conservation red-flag. It means increasing the number of tigers in Ranthambore will not help. Such disconnect signatures were shown by other large animals in the past before extinction,” Uma Ramakrishnan, a biologist at National Centre for Biological Sciences who studied the genetic variability of Indian tigers told Deccan Herald.
The warning has come at a time when India’s tiger count is on an upswing. The 2010 tiger count is 1,706 – an increase of 295 tigers from the 2006 tiger estimate of 1,411. According to an assessment made by scientists at Wildlife Institute of India, Ranthambore, Corbett, Dudhwa, Bandipur and Madhumalai are filled up to the brim but there is scope for tiger population to increase in Srisailam, Simlipal, Palamou and Satkosia.
Even though the subcontinent hosts 50-60 per cent of global tiger population, the zone lost vast stretches of forest areas for development works, resulting in not only elimination of tigers from Afghanistan but also segregation of gene pools.
“Loss of habitat leads to reduced gene flow and population isolation. Globally 93 per cent of tiger ranges are lost. Because of habitat destruction by humans and hunting, tigers now persist in small and isolated populations (20–120 individuals) in India,” Ramakrishnan said.
The findings have been published in the May 16 issue of the Proceedings of the Royal Society B.
The NCBS researchers along with their collaborators at the University of Cardiff studied genetic material from tiger species kept in the Natural History Museum in London and National Museum of Scotland in Edinburgh.
The historical samples were subsequently compared with modern tigers. They found modern tigers are genetically more disconnected than historical population.