How a squirrel’s identity crisis sparked off a scientific quest in Kerala

The latest issue of ‘Current Science’ features Alison, the melanistic Indian palm squirrel, on the cover.   | Photo Credit: STALIN

A black squirrel is indeed a rarity, at least in India, but what would have ended up in captivity as a curious exhibit or a laboratory specimen, instead became the subject of a 13-year-long scientific quest by a multidisciplinary team of 15 researchers from various Indian institutes.

Employing a vast arsenal of the most modern scientific techniques, including morphological and bioinformatic studies and molecular and genetic tools, the scientists embarked on a mission to unravel the cause for the colour change in the rodent.

Capture in 2008

Ever since it was captured from the outskirts of the capital city in 2008, Alison, the black squirrel, named after a U.K.-based scientist who helped identify the animal, had been the subject of intense scientific scrutiny.

Following up on the preliminary investigations that confirmed the black animal to be a variant of the Indian three-striped palm squirrel (Funambulus palmarum), the scientists went on to decipher the genetic causes of the colour change. Finally, after 13 years of research, the team came up with the finding that the phenomenon was caused by gene mutation. The study found that the melanocortin-1 receptor (MC1R) gene in the animal acted as a switch to activate the change in pigmentation. The study has been published in the latest issue of Current Science which also features the picture of Alison on the cover.

Is it a squirrel?

“At first, we thought it was a tree shrew but the bushy tail resembled that of a squirrel. Our initial task was to identify the species, for which taxonomic and molecular studies were carried out. Once it was confirmed as a female melanistic variant of the Indian palm squirrel, we realised that it was the first black one of its kind to be reported from the Indian subcontinent,” says Oommen V. Oommen, former chairman, Kerala State Biodiversity Board and co-author of the paper.

Unlike the U.K., U.S., and Canada where the black squirrel has attained sizeable populations, there have been no reports of the mutant version being sighted anywhere in India.

The next job was to find out whether it was a new species, for which the scientists compared the genes of the wild squirrel with the black melanic variant and found they were 98% similar. Having confirmed it as a palm squirrel, they moved on to the quest to study the mutation. “Our attempt was to understand the basic science behind the colour change, what it is that throws the switch,” Prof. Oommen said.

The reason

Computational docking studies suggested that the mutation in the MC1R gene was responsible for the melanism.

In between, the researchers thought of releasing Alison into its natural habitat but gave up the idea as the squirrel had little chance of survival, given that it did not have the camouflage to protect it from predators. “In the end, a scientific quest of this nature is all about observing Nature, asking questions and trying to find answers,” says Prof. Oommen.

The research team included R. Dileepkumar, K. Anaswara, V. Navya, V. Deepthi, G. Renganayaki, P.R. Shidhi, P.R. Sudhakaran and Achuthsankar S. Nair from the Department of Computational Biology and Bioinformatics, University of Kerala, S. Beena, OmicsGen Life Sciences, Kochi; A. Jacob, Zoological Garden, Thiruvananthapuram; L. Divya, Department of Animal Sciences, Central University of Kerala; A.S. Vijayasree, Department of Zoology, Fatima Mata National College, Kollam; M.A. Akbarsha, Department of Biotechnology, National College, Tiruchirappalli; and K.P. Laladhas, St. Stephen’s College, Pathanapuram.

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Printable version | Sep 18, 2021 4:18:00 PM |

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