Genome sequence reveals big cats evolved to kill, eat meat

Mapping of genomes to help wildlife conservation efforts and combat wildlife crime

By Kumar Sambhav Shrivastava
Published: Thursday 19 September 2013

imageTigers have evolved to become one of the most ferocious predators among cats. At the genetic level, all the big cats are very close to each other, but what makes them distinct from each other are the small DNA differences in them. These are the findings of latest study which has for the first time mapped the whole genome sequence of the Amur (Siberian) tiger and genomic sequences of a white Bengal tiger, African lion, white African lion and snow leopard.

The genome mapping shows how tigers gained their extensive muscle strength, the metabolism to digest large quantity of meat and a keen sense of smell which help them hunt, find mate and demarcate territories.

Among the cats, so far only the DNA of domestic cat had been mapped. Interestingly, the mapping shows that the big cat is genetically very similar to the domestic one. “The tiger genome sequence shows 95.6 per cent similarity to the domestic cat from which it diverged approximately 10.8 million years ago,” says the study published in Nature Communications on September 17. The similarity between humans and gorilla that diverged around 8.8 million years ago is 94.8 per cent.

To understand what makes big cats such as tigers, lions and snow leopards distinct from each other, the study additionally sequenced the genomes of a Bengal (white) tiger, an African lion and an Asian snow leopard. For instance, two mutations were identified by the scientists which are likely responsible for snow leopard's adaptation to high altitudes and the white fur on white African lions.

The tiger, lion and snow leopard are some of the most endangered species and their conservation is considered of extreme importance to protect the ecosystem in which they survive. Earlier, there were nine sub species of tigers found in the world but now only four sub species, including the Siberian tiger and the royal Bengal tiger (found in Indian sub-continent) exist—these number less than 4,000  in the world. Scientists claim the genome mapping of the big cats can be a big breakthrough in conservation efforts.

“Our data from tigers, lions and snow leopard can provide a rich and diverse genome resource that could be used in future studies of conservation and population genomics so that the genetic underpinnings of local adaptation and potential inbreeding and/or out-breeding in wild and captive populations can be illuminated, and thereby help ensure the future survival of these majestic species,” says the study.

Priyvrat Gadhvi, an Ahmedabad-based biotechnologist and the India representative of the Genome Research Foundation in South Korea that conducted the study, said the study was a landmark achievement in conservation genetics. "The entire genetic blueprint (the genome) of the tiger and other big cats has been decoded. This has provided invaluable information on the species' adaption to environment, its evolution, genetic health and diversity as well as special attributes. The data from this project will form the basis of all future genome level studies on the species," said Gadhvi.

On the study's significance for India, Gadhvi said: "India is the single most important tiger range country, as well as for carnivores like the Asiatic lion, snow leopard and leopard. Data from this project will help Indian researchers in their studies to determine genetic diversities in different populations of the species in India, evolutionary studies, genetic tools to combat wildlife crime."


The tiger genome and comparative analysis with lion and snow leopard genomes

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