Two genetically different populations

Ignatius Pereira
KOLLAM,  
The Hindu, November 28, 2015

The lion-tailed macaques ( Macaca silenus ) which are found only in forests from the central to the southernmost tip of the Western Ghats are not a single entity. A recent scientific study has shown that the 4,000 monkeys that survive now comprise two genetically different populations.

The most prominent break in the Western Ghats is the Palghat gap, which is about 40 km wide. South of the gap, the macaque habitats are highly fragmented, compared to the habitats in the contiguous forests in the north. The study shows that the lion-tailed macaques living north of the Palghat gap are genetically different from those living in the south.

The study says that although the lion-tailed macaque has a relatively wide range south of the gap, its area of occupancy is small and severely fragmented. Small populations in isolation, especially in fragmented landscapes, are known to lose genetic variability, suffer from inbreeding depression, and become genetically differentiated among themselves.

The finding is that those in the south have low mitochondrial DNA diversity compared to those in the north. “These populations can be considered as separate conservation units and should be treated separately in captive breeding programmes. Any reintroductions to the wild should be done after ascertaining the correct geographic origin of the individual.”

The study recommends that some of these isolated fragments be connected by planting food trees that would establish canopy corridors between them to facilitate gene flow.

The study, ‘Prehistoric and recent vicariance events shape genetic structure and diversity in endangered lion-tailed macaque in the Western Ghats: Implications for conservation,’ published in Plos One , a peer-reviewed open access scientific journal, on November 11, was conducted by Muthuvarmadam S. Ram, Minal Marne, Ajay Gaur, Honnavalli N. Kumara, Mewa Singh, Ajith Kumar, and Govindhaswamy Umapathy.

It was jointly funded by the Department of Biotechnology under the Union Ministry of Science and Technology and the Central Zoo Authority of India.

The study was carried out in the forests of Aghanashini, Karkala, Kundapur, and Kudremukh in Karnataka, Muthanga, Vazhikkadavu, Silent Valley, Nelliampathy, Kodanad, Vazhachal, Kollam, and Amboori in Kerala, and Anamalai, Meghamalai, and Kalakkad in Tamil Nadu.