A team of geneticists, conservation biologists and wildlife officials are in the process of preparing a genetic map — that is, tracing out the sequence of genes — from Machhli’s DNA, which was extracted at the time of her death.
“Machhli is an iconic individual, has lived long, has sired a large number of cubs and, because the tigers at Ranthambore are highly inbred, she would serve as an excellent example of the species. Plus, we were lucky to get permits and ideal tissue samples at the right time,” said Dr. Uma Ramakrishnan, at the National Centre for Biological Sciences (NCBS), Bengaluru, who is leading Machhli’s genome analysis.
Once the complete genome map is prepared, and this could take six months more, it could serve as a template, or ‘reference genome’, for comparing the genes of tigers anywhere, Dr. Ramakrishnan told
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Credited with reviving the tiger population at the Ranthambore National Park, Machhli, also known as T16, earned that name due to fish-like marks on her face. The 20-year-old tigress sired 11 cubs and was estimated to have brought in about ₹65 crore a year as tourism revenue to the National Park between 2006 and 2016.
So far, the reference genome that’s used to study tiger genetics is that of the Amur, the Siberian tiger that was sequenced in 2013. Earlier this year, the Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) claimed to have sequenced, for the first time, the whole genome of a Royal Bengal Tiger. This scientific report, however, is yet to be peer-reviewed. Rakesh Mishra, Director, CCMB, said that, ideally, a ‘reference genome’ ought to be one made from a composite of individuals. “Like how the human genome was sequenced from taking genetic signatures from a small group of individuals, a reference genome of a species ideally ought to be from a group of individuals [of that species],” he told The Hindu in a phone conversation.
Dr. Ramakrishnan said that she and her group, over the years, had sequenced, at varying degrees of resolution, genomes from several tigers. However, Machhli’s would be at an unprecedented level of detail and accuracy because multiple genome-reading technologies were being employed. Various traits of tigers, such as their sense of smell, strength and metabolism have been enriched in the species due to specific genes. “Once we have the reference, we can better understand functionality — where these genes are, [they exist in] which populations, how they are different,” she added.
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India has the maximum number of tigers in the world. Since 2006, the Wildlife Institute of India (WTI), an Environment Ministry-funded body, has been tasked with coordinating the tiger estimation exercise. The once-in-four-years exercise estimated, in 2006, that India had only 1,411 tigers. This rose to 1,706 in 2010 and 2,226 in 2014 in later editions, on the back of improved conservation measures and new estimation methods. The survey, divided into four phases, began last winter. The findings are expected to be revealed in early 2019.