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Scientists trace ancient origins of elusive Western Ghats Tree Mouse
In a groundbreaking discovery that redefines the evolutionary history of a rare rodent species, scientists from the Zoological Survey of India (ZSI) have successfully decoded the DNA of the Malabar Spiny Tree Mouse (Platacanthomys lasiurus), a species endemic to the Western Ghats. This marks the first-ever generation of DNA barcodes for the elusive species, placing it within a clearer taxonomic framework and revealing its lineage as an ancient Gondwanan relic. Molecular dating from this new research places the origin of the Malabar Spiny Tree Mouse's ancestors in the Eocene period, between 56 to 33.9 million years ago, indicating that the species likely survived major geological transformations while taking refuge in the forested hill ranges of the Western Ghats. (HT PHOTO)
The collaborative study, published in the latest July edition of the peer-reviewed 'Journal of Animal Diversity' from Lorestan University, Iran, involved researchers from various ZSI regional centres, including S S Talmale, K P Dinesh, and A Shabnam from the Western Regional Centre, Pune; Jafer Palot from the Western Ghats Regional Centre, Kozhikode; and K A Subramanian from the Southern Regional Centre, Chennai.
Although Platacanthomys lasiurus was first described in 1859, it has taken nearly 166 years to generate its genetic data. Molecular dating from this new research places the origin of the Malabar Spiny Tree Mouse's ancestors in the Eocene period, between 56 to 33.9 million years ago, indicating that the species likely survived major geological transformations while taking refuge in the forested hill ranges of the Western Ghats.
The mouse is believed to be a living fossil, with no close relatives in India. A similar-looking rodent, the Chinese Pygmy Dormouse (Typhlomys), is found in China and Vietnam. However, molecular analysis shows that the two species are not monophyletic - meaning they do not share a recent common ancestor - supporting their placement in separate families. The lineage of Typhlomys is estimated to have diverged during the Miocene period, much later than Platacanthomys.
The discovery was made during a small mammal survey near Suryamudi in the southern Western Ghats, specifically in Kerala's Aralam Wildlife Sanctuary. The collected specimen is now housed in the National Zoological Collection at ZSI's Western Regional Centre in Pune for future reference and study.
Dhiriti Banerjee, director of the Zoological Survey of India, emphasised the importance of such studies in the context of climate change. She stated that integrative approaches, combining traditional taxonomy with molecular tools, are vital for informing conservation strategies and ensuring the survival of vulnerable species.
Lead author Dr S S Talmale highlighted that habitat degradation remains the primary threat to the Malabar Spiny Tree Mouse, which is listed as 'vulnerable' on the IUCN Red List. Found at elevations ranging from 50 to 2,270 metres, the species has a fragmented and highly-restricted distribution. It is also listed under Schedule II of the Wildlife (Protection) Amendment Act, 2022, which offers legal protection and underscores the urgent need for habitat conservation.
Co-author Dr K A Subramanian noted that the study reinforces the theory that the southern Western Ghats served as a biological refugium during the breakup of the ancient Gondwana supercontinent, supporting ancient lineages that are otherwise extinct elsewhere. Dr M J Palot described the field discovery of the specimen as a rare and emotional moment, adding that the opportunity to sequence its DNA has deepened scientific understanding of the region's evolutionary heritage.
Dr K P Dinesh added that molecular tools such as DNA barcoding and phylogenetics are crucial for studying relict species like Platacanthomys lasiurus. These techniques not only uncover hidden evolutionary pathways but also aid in precise taxonomic classification and targeted conservation efforts in biodiversity hotspots.
The findings not only elevate the conservation significance of the Malabar Spiny Tree Mouse but also open new avenues for research into its ecological history. The study is expected to inspire young researchers and students to explore the evolutionary mysteries of the Western Ghats, a region increasingly being recognised as a treasure trove of ancient and unique biodiversity.
