CHENNAI: In a pioneering study conducted by researchers at the Advanced Institute of Wildlife Conservation (AIWC), the evolutionary history of the Nilgiri Tahr (Nilgiritragus hylocrius) has been examined at the molecular level for the first time. The research, which analysed the mitochondrial genome of three tahr species, revealed surprising insights. While the Arabian and Himalayan tahrs share closer genetic ties with goats (Capra), the Nilgiri Tahr is more closely related to sheep (Ovis). This revelation challenges conventional taxonomic classification and sheds light on the evolutionary divergence that took place over millions of years.
According to the study, the tahr lineage emerged from a common ancestor approximately 11.5 million years ago (MYA). The Arabian Tahr (Arabitragus jayakari) was the first to diverge around 5.5 MYA, followed by the Nilgiri Tahr at 4.5 MYA, and finally, the Himalayan Tahr (Hemitragus jemlahicus) around 3 MYA. The evolutionary split of sheep and goats occurred separately, with goats diverging from the common ancestor around 7.5 MYA and sheep around 4.5 MYA. Continental drift and environmental pressures likely contributed to these evolutionary adaptations, leading to distinct morphological and genetic traits among the species.
The study’s findings were presented during the annual conference of the Advanced Institute of Wildlife Conservation (AIWC) by its senior research fellow R Madhumita. M G Ganesan, director, Project Nilgiri Tahr told TNIE: “The evolutionary biology of the Nilgiri Tahr is very much essential to understand the origin of the species, their genetic make up with other caprini species, long term sustainability of the tahr population, population genetics etc.”
At the AIWC conference, researchers also presented a metagenomic study on the gut microbiome of Nilgiri Tahr populations. Findings indicate that tahrs in the Anamalai Tiger Reserve (ATR) and Kalakkad-Mundanthurai Tiger Reserve (KMTR) possess a healthy and diverse gut microbiome, whereas the population in the Theni region exhibits lower microbial diversity. Scientists suggest that habitat quality and dietary resources may influence gut health, highlighting the need for further investigation.
Additionally, dietary profiling of major grass species consumed by the Nilgiri Tahr is underway to create a reference database for plant genomic studies. Electron microscopic analysis of Nilgiri Tahr hair has also been conducted to better understand its adaptation to high-altitude environments.
Recognising the ecological significance of the Nilgiri Tahr, Chief Minister M K Stalin launched Project Nilgiri Tahr on October 12, 2023, to ensure the species’ long-term survival. The project focuses on synchronised population surveys, removal of invasive species, restoration of grasslands, public awareness programmes, eco-development initiatives, and health monitoring of Nilgiri Tahr populations.
The species is endemic to the southern Western Ghats and is primarily found in Tamil Nadu and Kerala, with key populations in Anamalai, Mudumalai, Kalakkad-Mundanthurai, and Srivilliputhur-Megamalai Tiger Reserves. As part of habitat assessment efforts, researchers identified 45 grass species under 21 genera in the Anamalai Hills alone. Across Tamil Nadu, 72 grass species have been recorded in Nilgiri Tahr habitats, with 35 identified as primary food sources.
Grasslands play an essential role in supporting Nilgiri Tahr populations and maintaining ecological balance. The study has identified 38 key Nilgiri Tahr habitats in regions such as Tirupur and Pollachi. Researchers have found that Poaceae, one of the largest plant families, provides critical sustenance to both wild herbivores and human communities.
Grass species such as Arundinella mesophylla, Heteropogon contortus, and Themeda triandra dominate Nilgiri Tahr habitats, ensuring soil stability and preventing erosion. The study has also identified 25 grass species as primary fodder sources, with 15 species’ seeds being collected for conservation efforts. Understanding grassland health is now a priority in wildlife conservation, as it directly influences Nilgiri Tahr population dynamics, B Subbaiyan, senior research fellow at Project Nilgiri Tahr told TNIE after making a presentation on inventory of grass species during the AIWC conference.
Despite conservation efforts, the Nilgiri Tahr habitat faces several threats, including forest fires, uncontrolled cattle grazing, infrastructure development, invasive plant species, and poaching. In some areas, such as Mukurthi National Park, researchers have observed tahrs consuming invasive species like Cytisus scoparius and Eupatorium glandulosum, indicating potential shifts in dietary habits due to habitat alterations.
Grassland health remains a critical factor influencing Nilgiri Tahr populations. Fragmented grasslands with sparse tahr populations indicate declining ecosystem health, warranting urgent intervention. Researchers are now assessing factors such as grassland nutritional status, competition from other species, and the impact of forest fires on habitat degradation.
To enhance conservation outcomes, wildlife scientists emphasise the need for advanced monitoring techniques, habitat restoration, and community participation. Remote sensing technology and drone surveillance are being explored to track Nilgiri Tahr movements and detect habitat changes in real time. The introduction of native grass species and controlled burning techniques could also help manage invasive plants that threaten grassland ecosystems.
Community-based conservation efforts have also been proposed to involve local populations in protecting the species. Livelihood programmes promoting sustainable grazing practices and eco-tourism initiatives could serve as incentives for conservation. Researchers suggest that awareness programmes in Nilgiri Tahr habitats will be instrumental in fostering a culture of environmental responsibility.
Additionally, scientists are calling for increased funding for genetic studies. With ongoing studies and conservation initiatives, scientists and policymakers aim to safeguard the future of the Nilgiri Tahr while preserving its fragile montane ecosystem for generations to come.
Additional Chief Secretary Supriya Sahu told TNIE, Project Nilgiri Tahr is one of the iconic projects of the government. “The project team has achieved remarkable milestones and done some groundbreaking work, but there is a lot more to be done like reintroduction of tahr in suitable habitats for which studies are going on.”