Tropical Forests Turned South India Into Global Biodiversity Hotspot
These events certainly inflicted changes in the ranges and habitats of organisms, disrupting their earlier evolutionary trends,” explained the researchers.
Hyderabad:Peninsular India harbours unique and highly diverse groups of animal and plant species, endemic to this region. But how did this high endemic diversity originate and what factors contributed to it? A recent study from the CSIR-Centre for Cellular and Molecular Biology (CCMB) uncovers how species of life forms evolved and disappeared across South Asia. The study was published in 'Ecology Letters'.
Dr Jahnavi Joshi’s team at CCMB Hyderabad undertook the study of diversity of animal and plants species in peninsular India, which is a tropical region extending southwards from the Aravalli Mountains, including the Satpuras and Vindhyas, the Eastern Ghats, the Deccan Plateau, and a global biodiversity hotspot — the Western Ghats.
By analysing 33 well-studied groups of animals and plants using mathematical models, the team traced patterns of species formation (speciation) and loss (extinction) across the region. Such a broad-scale analysis has been done for Asia for the first time.
“Each of the groups comprises closely related endemic species and a common ancestor that existed at some point in time. Through millions of years, their descendants spread across the landscape and diversified into multiple species, many of which exist today,” explained Dr Joshi.
The researchers found a high disparity in how species are formed or lost across groups of animals and plants. They found evolutionarily related groups, such as different kinds of lizards exhibited similar rates of forming and losing species. They also noted that half of the animal and plant groups accumulated diversity gradually over millions of years.
“The stability of the tropical forest ecosystems in peninsular India has allowed for such steady diversification. This area has shielded species from severe climate changes,” commented Dr Joshi.
The stability of this ecosystem is surprising given the turbulent geo-climatic past of the landmass. “Peninsular India was once part of the Gondwanaland supercontinent with land masses like Africa and Australia. It broke away 140 million years ago, drifted northward, and eventually collided with Asia, forming the Himalayas. Despite drastic geo-climatic shifts from this movement, the biodiversity in this region has changed rather steadily. This highlights the fascinating resilience of its forest habitats,” added Pragyadeep Roy, the first author of the study.
While on one hand these changes were slow and steady, there were other groups that evolved and lost more dynamically. The remaining half of the groups experienced fluctuating rates of new species forming and losing over time. “The global temperatures have been very dynamic across several million years and our analyses suggest that earth’s temperature strongly influences how species are formed in many groups,” explained Roy.
The study found that some groups experienced abrupt changes in the rates of forming new species within th time range of 11 to 3 million years ago. “This period was marked by high aridification and monsoon seasonality in peninsular India with a major expansion of grasses, leading to the shrinkage of evergreen forests to the Western Ghats and the mountaintops of the Eastern Ghats. These events certainly inflicted changes in the ranges and habitats of organisms, disrupting their earlier evolutionary trends,” explained the researchers.
These insights into how past climate and habitat stability influenced biodiversity can prove crucial in devising effective conservation strategies, especially in light of anthropogenic activities and climate change.
