Odd, Different, But Not Peculiar!
April 2011: Strange looking sambar? For a micro-moment that’s what I thought too… until I noticed the horns and body shape; at which point I did a double take! The image, sent to us by Sanjayan Kumar, Deputy Director of the Periyar Tiger Reserve, is that of a chital or spotted deer Axis axis! He took the photograph in a bamboo-studded, well-watered patch of Parambikulam’s shola forest, where he said the ‘dark lord’ seemed to be leading the herd! Kumar says the first thought that came to mind was that this was the same melanism at play that created black leopards (see cover, Sanctuary Vol. XXX No. 6, December 2010).
He was bang on. The lack of spots and dark pelage is indeed the result of melanism caused by a recessive gene that crops up about as frequently in nature as albinism. Down the ages, melanism has fascinated naturalists and scientists alike and debates as to its usefulness or otherwise in the high-stakes game of survival are as vibrant today as they were when Darwin shook the foundations of the world of science with his theory of evolution.
Geneticists are particularly interested in melanism as it graphically helps fill in the blanks on how traits are passed from generation to generation. Physical characteristics can be passed through heredity, shaped by the environment or a combination of both. But it is more complicated than that. For instance, when an animal with recessive genes interbreeds with a normal deer the characteristic might not be handed down to successive generations. And, if a dark and albino deer mate, it is entirely possible that a normal-coloured fawn might result!
Thus far the best known studies on melanism have centred around insects such as the peppered moth Biston betularia, which revealed that industrial pollution favoured the survival of darker moths. But with humans having assumed the position of powerful, evolutionary change-makers, altering both climate and geography at a blistering pace, who knows what tomorrow’s studies will reveal? Rising temperatures, some say, could well favour lighter-coloured species that reflect, rather than absorb, heat. But even such strategies need time to adapt. That commodity Homo sapiens is denying not only to tigers, elephants and this tall, dark and handsome chital, but even to himself. To our cost, we may therefore discover that nature, which has proven to be kind to the odd and different, may not necessarily be quite as generous to the peculiar!
Bittu Sahgal, Editor, Sanctuary Asia, Vol XXXI No. 1, April 2011