Guwahati: A ground-breaking study published in Ecology and Evolution has shed new light on the role of historical climate change in shaping the diversity of primates in Northeast India. The research, conducted by an international team of scientists, uses species distribution models and whole-genome sequencing to trace how past climatic fluctuations influenced the region’s primate speciation and population dynamics.
The study focused on nine primate species from four genera—Macaca, Trachypithecus, Hoolock, and Nycticebus—analyzing their historical demography alongside species distribution models from the Pliocene and Pleistocene epochs. The findings reveal that while the effective population size of all studied species has declined over time, their historical distributions varied, with some expanding while others contracting in response to climate shifts.
Northeast India: A Crucial Hub for Primate Evolution
Northeast India, part of the Indo-Burma biodiversity hotspot, is home to 14 primate species. The region’s unique geography, ranging from the Eastern Himalayas to the Brahmaputra and Barak river valleys, has long been considered a prime area for studying species diversification. According to the researchers, past climatic fluctuations played a crucial role in driving primate speciation in the region.
Using whole-genome sequencing data, the researchers inferred the demographic history of the primates and compared it with species distribution models spanning millions of years. Their analysis found that different species responded uniquely to past climatic events, emphasizing the need for species-specific conservation approaches in the face of ongoing climate change.
Key Findings: A Story of Rise and Decline
The study found that the effective population sizes of primates in Northeast India peaked during the mid-Pleistocene before experiencing a steady decline. However, distribution models showed varying patterns.
The study suggests that Macaca assamensis and M. thibetana likely diverged between 700,000 and 800,000 years ago, with one species spreading westward into the Himalayan foothills and the other expanding toward Tibet and southern China. Trachypithecus pileatus had a large population size around 3.3 million years ago but saw a decline with the onset of the Pleistocene. Its relative, T. geei, likely diverged from T. pileatus during this time, possibly due to climate-induced habitat fragmentation.
The slow loris species, Nycticebus bengalensis, thrived in the mid-Pleistocene but faced a sharp decline due to climatic fluctuations, highlighting its vulnerability to environmental change. The western hoolock gibbon (Hoolock hoolock) displayed a rise in population in the mid-Pleistocene but experienced a steep decline in recent history, possibly due to habitat loss and climate shifts.
Conservation Implications
The findings underscore the urgency of developing tailored conservation strategies for each species. “Understanding how different primate species responded to past climate events can help us predict their future in the face of ongoing global warming,” said Govindhaswamy Umapathy, lead author of the study from the CSIR-Centre for Cellular and Molecular Biology, Hyderabad.
The study also highlights the importance of preserving Northeast India’s forests, which serve as crucial refuges for primates. With deforestation and habitat fragmentation threatening wildlife in the region, conservation efforts must be prioritized to prevent further population declines.
As climate change continues to alter ecosystems worldwide, studies like this provide invaluable insights into how species adapt—or struggle—to survive. The researchers call for further investigations into the evolutionary history of primates and other taxa in Northeast India, emphasizing the need for a comprehensive conservation framework.
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