A path-breaking endeavour to avoid genetic incompatibility

Sariska's tiger breeding hopes were revived on Tuesday with a tiger being brought to the reserve from the Ranthambhore reserve. It was selected after his DNA was analysed in a bid to avoid the genetic incompatibility that has plagued Sariska's relocation programme so far.

In fact, it was the first time in India that genetic studies were undertaken to identify tigers suitable for translocation. Two of the 12 scat samples from the Ranthambhore reserve that were sent for DNA analysis came out positive. Apart from the tiger shifted on Tuesday, a tigress will also be moved there within the next few weeks. The study showed that both animals were not too closely related to the Sariska tigers, or to each other.

“This is the first time that genetic studies have been conducted to select tigers,” said Union Minister of State for Environment and Forests Jairam Ramesh after the DNA analysis results were received this past Friday.

“Until now we went by normal field-level analysis…..However, after all the fears that have been raised about siblings being relocated, we thought it was best to do this in a scientific way.”

The Sariska tiger reserve in Rajasthan lost the last of its own tigers some time in 2004 or 2005, mostly due to widespread poaching. The bid to return tigers to the reserve, therefore, depends on shifting tigers from other reserves. Accordingly in 2008 and 2009 three tigers — a male and two females — from Ranthambhore reserve, also in Rajasthan, were moved to Sariska. However, they have failed to produce any offspring, and it was later discovered that they were siblings.

The translocation programme was put on hold while the Central Government tried to persuade Madhya Pradesh and Maharashtra to donate a few of their tigers to re-populate Sariska in order to avoid using the same gene pool from Ranthambhore. Last week, however, Madhya Pradesh Forest Minister Sartaj Singh made it clear that his state had no surplus tiger to send to Rajasthan.

The news of the DNA results of the Ranthambhore scat samples injected new life into the translocation programme, since inter-state transfer hurdles can be avoided.

The DNA analysis was carried out by Uma Ramakrishnan of the National Centre for Biological Sciences, a part of the Tata Institute of Fundamental Research based in Bangalore. Of the 12 scats collected, genetic analysis showed that only eight came from tigers. One more sample did not have a sufficient quantity of DNA data and was also dropped from the study.

While five samples were from tigers which were siblings, and in one case a half-sibling, to the Sariska animals, two samples were found suitable. They have a zero-level of relationship to one of the Sariska tigers and a 0.24 and 0.4 level of relationship to the other.

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