A new study has found four distinct sub-populations of leopards in India with high genetic variations — leopards of the Western Ghats, the Deccan Plateau semi-arid region, the Shivalik mountains, and the Terai region in North India. The assessment of genetic data has also revealed a possibly human-induced population decline of 75% to 90% among leopards in India in the past 120 to 200 years.
The findings are significant because leopards are otherwise among the most adaptable carnivores, and are known to exist very close to human habitations.
The authors of the study, published in the journal PeerJ on February 4, have recommended that similar conservation attention be given to leopards as is given to tigers to contain a further decline in distribution and numbers.
The authors from the Dehradun-based Wildlife Institute of India (WII) and the Bengaluru-based Centre for Wildlife Studies (CWS) used faecal samples to study genetic markers that revealed genetic variations and the demographic history of leopards. They used historical records to obtain a set of locations where leopards were known to have been present at some time in the last 200 years, and then used occupancy estimation models to estimate the current presence in the same locations.
“The results of the study showed that coalescent simulations with microsatellite loci (DNA signatures which help understand differences among sub-populations) revealed, across India, a possibly human-induced 75% to –90% population decline between approximately 120 to 200 years ago,” the study stated.
These four genetic groups which the authors found during their study correspond to biogeographic zones of India. Western Ghats and combination of Deccan Plateau semi-arid region form two sub-populations, and the north Indian sub-population of Shivalik and Terai are part of the Himalayan mountain and Gangetic plains zones.
“We presume that these genetic clusters were formed due to restricted gene flow along major habitat type differences between these biogeographic zones. For example, the difference between habitat types of large contiguously forested Western Ghats (largely moist deciduous habitat) and the Deccan Plateau semi-arid (mostly dry deciduous habitat) probably lead to genetic differences between leopards from these regions. Similarly, difference in habitat types in the ‘Bhabar’ habitats of Shivalik (hilly rugged terrains, large trees, high leopard abundance) and Terai region (flat terrain, grassland, low leopard abundance) has possibly led to reduced gene flow between these two areas,” the study added.
A number of factors may have led to such a steep decline in the distribution of leopards. “In the 1850s to 1950s, there was a lot of trophy hunting of all large wildlife, including tigers, leopards and rhinos. After the 1900s, there was large-scale decline in habitats, particularly grasslands and scrubland. There was also a deterioration in the quality of forests leading to prey loss. The decline in their spatial distribution may be a result of all of this. The decline is worrying because we may be pushing the species to its limits,” said Krithi K Karanth, chief conservation scientist at CWS.
“We know that most wildlife population in India recorded a major decline with human population growth in the 1800s and 1900s, which led to habitat fragmentation, hunting, and loss of forests. However, there is a need to quantitatively assess this decline. This is probably the first study to use genetic tools to quantify decline in leopard populations,” said Aritra Kshettry, senior research fellow, department of science and technology, and wildlife biologist.
Kshettry added that leopards in India may have been a single population but isolated over time due to habitat loss into sub-populations.
“They are extremely adaptable animals. There is no evidence of major decline in their populations in recent years. They exist inside and outside forest areas close to human habitations,” Kshettry said.
