- India should extend the focus of its tiger conservation programmes from high-profile reserves to areas that harbour unique genetic diversity, recommends a recent study, emphasising that genetic data should guide conservation efforts.
- Priority areas for tiger conservation efforts should be north-east India, especially the hills; Simlipal-Palamau area of Odisha; and the southern Western Ghats.
- Study says north-eastern tiger populations merit the status of a unique population unit of high conservation value.
A recent study, by scientists from the Wildlife Institute of India (WII) in Dehradun, Uttarakhand, states that India needs a paradigm shift in its tiger conservation approach.
India should stop “indiscriminately doubling” tiger numbers and extend the focus of its tiger conservation programmes from selected high-profile reserves to areas that are currently under-represented but harbour unique genetic diversity, recommends the study.
Within India, priority areas for tiger conservation efforts should be north-east India, especially the hills; Simlipal-Palamau area of Odisha; and the southern Western Ghats. This would help ensure that their unique evolutionary lineages are not lost forever, the WII scientists said in the study. “All these three areas now have low tiger numbers yet harbour unique diversity that is currently under-represented and not prioritized for conservation investments,” they noted.
Conservation investment, at present, is the highest in high-profile tiger reserves with large tiger populations like Kanha (Madhya Pradesh), Corbett (Uttarakhand) and Bandipur (Karnataka).
Research also suggests that introduction and supplementation of tigers in reserves should factor in similar broad genetic clusters. Given the wide range of tiger habitats, with varying climates and prey, it would be necessary to first understand the underlying genetic diversity of their populations, a result of both natural, historical events and adaptation to habitats. Conservation strategies need to be planned accordingly to preserve this diversity, states the study.
A genetic study with many firsts
India is uniquely placed in terms of its people and tigers – it houses 17.5% of the world’s people on a mere 2.4% of the world’s surface area. India is also home to over 76% of the world’s surviving wild tiger population, currently estimated at over 2,967.
The country’s estimated tiger count has been on a rise, increasing from 1,411 in 2006 and 1,706 in 2010 to 2,226 in 2014, according to Global Tiger Forum (GTF) general secretary Rajesh Gopal at a GTF conference in New Delhi in January 2019. The GTF is an inter-governmental international body working together to protect tigers.
Yadvendradev Jhala, a senior scientist at the Wildlife Institute of India, Dehradun and one of the authors of the paper, told Mongabay-India that the country has, in fact, “done really well in conserving its tigers,” as indicated by an increase in tigers numbers. This is mainly due to the Indian government’s policy and resources to create a secure space for tigers, he said.
Tigers currently occupy around 90,000 square km of the 350,000 square km of forests available within their range in 20 Indian states, said Jhala, adding that there is a large amount of habitat still available.
Jhala explained that while the global goal set in at the international tiger summit in 2010 at St. Petersburg was to double the tiger population by 2022, the new paper by the research team shows that it is more important to identify and ensure the survival of the entire gene-pool of tigers so that the entire genetic range of these big cats is retained, than merely focusing on doubling numbers.
“In the light of this, we identify the genetic structure of all tiger populations in India and prioritise them on the basis of their genetic distinctiveness, diversity and population status,” he said.
For their study, the WII scientists collected scat droppings from a sample of 158 tigers, covering 34 tiger populations from all major tiger landscapes in India, between December 2013 and December 2014. They studied 11 ‘microsatellites’ – a set of repeated sequences of genetic material or deoxyribonucleic acid (DNA) at a particular spot in a chromosome. Microsatellites are widely used to study genetic linkages within and between populations and to measure levels of relatedness between population groups and even individuals.
The use of 11 microsatellite loci, or specific points, helped the scientists delineate population clusters. Their approach was different from previous studies on tigers in India, which were either limited by low sample size or restricted to a particular landscape or used inappropriate species-specific markers, the report said. The study is also the first genetic study with samples from Namdapha tiger reserve and Dibang valley in Arunachal Pradesh, where low densities of tigers were expected.
The study revealed three population clusters of tigers in India: unique north-eastern tigers; a combined cluster of Western Ghats, western India and Terai tigers; and a mixed cluster from central India. The scientists found that tiger populations from Odisha, Valmiki (Bihar) and the southern Western Ghats were “distinct”, with distinguishing genetic material not found in other groups; and that the central Indian tigers were the most varied group.
The north-east revelation
Some of the most crucial insights concerned tigers in north-east India, which were found to have unique genetic material.
The north-eastern landscape is one of the most globally biodiverse regions and the results of the study clearly show the genetic separation of the north-eastern tigers from the rest of the Indian tiger populations. A plausible reason for the distinction of north-eastern tigers could be due to the sharing of genetic material with the Indo-Chinese tiger population (Panthera tigris corbetti) that borders the north-eastern states, the report adds.
The results also highlight the importance of north-eastern tigers due to their divergent genetic constitution. The highland tiger populations of Dibang and Namdapha were found to be different from those of the plains and foothill populations of the Kaziranga (Assam)-Manas (Assam)-Buxa (West Bengal) complex.
In view of the new results and the already low density and small tiger numbers in the north-eastern hill region, “the north-eastern tiger populations merit the status of a special population unit of high conservation value” and the two sub-groups of highland and lowland tigers should be managed separately, the scientists suggest.
The scientists suggest a paradigm shift from “indiscriminately doubling” tiger numbers to prioritising conservation of naturally occurring diversity amongst tigers and focusing on restoration based on genetic similarity in an area.
“Considering a combined analysis of population size, genetic diversity and uniqueness, tigers from the North-East hills, and the southern Western Ghats emerge as conservation priorities,” the report says. According to the report, tigers should be reintroduced into reserves, or added to other reserves to increase the latter’s numbers, based on genetic traits.
For effective conservation of tigers, it would be essential that each of the naturally occurring genetic clusters has enough numbers of tigers for them to survive either as a single localised group or as part of a bigger group.
For example, northeast India is one of the most important regions in the world for biodiversity conservation. The tigers from this region are genetically unique and distinct from other populations in India, points out Jhala. “Also, especially in the northeast hills, the tiger populations are very small and vulnerable. This is where targeted conservation investments are required.”
That said, it is easier said than done, as the logistics of management are difficult, hunting is common and the prey base is substantially lower in these forests, he points out. The terrain is difficult with poor infrastructure. “The key is to work with the local communities and connect tiger conservation with enhanced livelihoods and make offer livelihood options that make use of forest resources sustainable.”
The results of this study, the scientists say, provide “a critical baseline on how tiger populations are genetically structured in India.” They can also guide managers in making decisions on interventions of supplementation; genetic rescue and in selecting source populations for translocations, and prioritising investments in conservation efforts.
Genetic data key to successful conservation efforts
This is the third study to look at the population structure of Indian tigers, but the previous two studies had fewer samples, said Uma Ramakrishnan, professor at the National Centre for Biological Sciences (NCBS), Bengaluru, not associated with this study. Her team had published the previous two reports, one in PLoS Biology in 2009 and the other in Nature in 2017.
These studies had looked across the tiger genome at 10,000 genetic ‘markers’ (genetic material or deoxyribose nucleic acid (DNA) sequence with a known location on a chromosome that can be used to identify individuals or species) but also had lower geographic sampling. “This paper has extensive geographic coverage and it is especially exciting to see the samples from the southern Western Ghats and the north-east which have not been sampled adequately before,” said Ramakrishnan.
The results show that although the tigers of the north-east, central India and the southern Western Ghats are unique in terms of being genetically different from other populations, their current population size is low. This means that their conservation value is high, but since their population size is low, it makes them a high priority for conservation action.
Wildlife scientists were aware of some of these aspects of tiger population differences, “but lacked empirical evidence which has now been provided by the study,” said Rahul Kaul, chief ecologist at the Wildlife Trust of India, Delhi. The scientists have also “gone a few steps deeper to assess gene flows across populations, thereby deducing the unique nature of north-east populations, perhaps because they are isolated and have evolved in that manner.”
Kaul adds that tiger conservation in India is at a crossroads today and it is necessary to have a relook at how we conserve our tigers. Some populations are doing extremely well, with perhaps better protection under the protected areas (PAs) and are even beginning to disperse to adjoining areas causing conflict with local people in the adjoining areas – something that cannot be good for conservation.
The government needs to see how many tigers it wants in each landscape and work towards that, said Kaul. The situation is not the same all over India; there are large parcels of land from where tigers have disappeared altogether or are found in very low density. Investing in such areas need to be higher so that appropriate infrastructure – such as more staff, better patrolling, and more prey – is developed to create conditions conducive for the increase in tiger numbers.
“I think we must continue using genetic data from tigers to explore population connectivity and inbreeding/isolation,” said Ramakrishnan. Genetic data is sure to provide interesting insights for conservation, especially with genomics-based methods becoming affordable, she said, adding: “To my mind, continued fragmentation and the ensuing isolation of certain populations will continue to be a big conservation problem as will human-wildlife conflict with carnivores like tigers.”
Kolipakam, V., Singh, S., Pant, B., Qureshi, Q., & Jhala, Y. V. (2019). Genetic structure of tigers (Panthera tigris tigris) in India and its implications for conservation. Global Ecology and Conservation, 20, e00710.
Banner image: Study emphasises that genetic data should guide conservation efforts. Photo from Unsplash.