Himalayan glaciation and its effects on terrestrial and freshwater animal life in Peninsular India

One of the most remarkable features of the zoogeography of India is the occurrence of the so-called Malayan element in the freshwater and terrestrial fauna of the Indian Peninsula. This element is rich in species and genera of practically all groups of non-marine animals which are found in the hills of Peninsular India and Ceylon on the one hand and in the Eastern Himalayas, hills of Assam and Burma and Farther East on the other. The absence of this characteristic fauna from the rest of India and the present-day discontinuous distribution of a large assemblage of genera and species of Malayan affinities have attracted the attention of the naturalists for the last half a century or so. Geologists have used these distributional anomolies as collateral evidence of a cold period having affected the whole of India and Ceylon in the late Tertiary or post-Tertiary times. In this connection, reference may be made from among others to MEDLICOTT and BLANFORD (1879, pp. lxx, 374, 375), OLDHAM (1893, pp. 14, 15) and WADIA (1944, pp. 277, 278). MEDLICOTT and BLANFORD in their introductory account of the Glacial Epoch (p. lxx) stated: ... ""Among the most potent disturbing causes that have affected the fauna of India in late geological times, the general refrigeration of the area in the glacial epoch has in all probability played a conspicuous part. The former extension of the Himalayan glaciers has been shewn to have been considerable; and the occurrence of Himalayan plants and animals on the higher ranges of Southern India may be due to the retreat of these species in the first place towards the equator, and subsequently, as the temperature increased, to the higher parts of the hills. As examples, the occurrence of a Himalayan rhododendron, of a wild goat allied to a Himalayan species, and of several Himalayan land shells on the Nilgiri and other Southeri Indian hills may be mentioned It is not impossible that the distinction between the Malabar and Malay faunas has been intensified by their separation, due to the climate of Northern India having been too cold for them in the glacial epoch.""