From the lab: In study on survival, a surprise finding; new species

A few years ago, studies in the US had claimed that the pika population in that country was declining as a result of global warming.

Written by Nishma Dahal & Team | Published:October 24, 2016 4:15 am
pika, pika species, rat species, pika rats, pika research, pika research study, rats research, rats research study, science news The pika of Sikkim. Photo courtesy the researchers, who have proposed that it be called Ochotona sikimaria. (Source: Prasenjeet Yadav)

A PIKA is a small mammal found in the colder climates of Himalayas, and in some other parts of the world. By outer appearance, they can resemble small rats but are very different. There are several species within the pika family. In the Indian region, they are mostly found in locations that are over 2600 metres above sea level. These species are quite common in Sikkim and also in Arunachal Pradesh, Uttarakhand, Himachal Pradesh, and central Nepal.

A few years ago, studies in the US had claimed that the pika population in that country was declining as a result of global warming. For my PhD, I tried to test this hypothesis on pika species found in India. Since pikas can survive only at certain cold temperatures, a rise in temperature would force them to migrate to cooler areas or make them extinct.

For my field study, I chose to travel to Sikkim, which is not just a common habitat for pika species but also happened to be my home state. Since pikas are very small and difficult to capture, we collected the faecal matter of the most commonly found pika in this area to extract its DNA. When we compared this DNA with existing DNA sequences of pika done elsewhere, we noticed very distinct differences.

Now, faecal matter as a source of DNA can be a tricky affair. In carnivorous animals, the faeces can also contain the DNA of the prey. Since pikas are herbivores, this was not a very big concern. But the differences in the DNA sequences of the samples collected by us and in existing repositories forced us to look at our methods more closely. We then decided to extract the DNA directly from the pika, for which we captured a few of these animals. The differences in DNA sequences remained. Surprisingly, this pika’s DNA sequence was nowhere close to its sister species, those it resembled the most within the family.

By this time, it was becoming clear to us that we were looking at a new species in the pika family that was so far being wrongly labelled a sub-species. It was a surprising find considering that the pika that we were studying was not rare by any means. It is quite common in Sikkim, and its specimens are found not just in India but also in museums abroad. But pikas, especially in the Himalayan region, have not been studied extensively. And the genes of each of the species within the family are still to be mapped.

We have published our finding in the journal Molecular Phylogenetics and Evolution and have proposed that the new species be named Ochotona sikimaria.

While the discovery has been an interesting and important, even though unexpected, milestone, the investigation into the impact of global warming on the pika population is still going on. The field study has been completed and we are now analysing the data we have collected. Our main objective is to create a demographic history of the pika in the Himalayas and find out whether its population, especially in the lower altitudes, is in decline.

National Centre for Biological Sciences at Tata Institute of Fundamental Research, Mumbai.

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