Some extreme estimates range from 20 to 50 million, but a more conservative and scientifically sound estimate made by Robert May places the global species diversity at about 7 million. Although India has only 2.4 per cent of the world's land area, its share of the global species diversity is an impressive 8.1 per cent.

Understanding Global Species Diversity
The estimate of global species diversity is a topic of significant interest in ecology and conservation biology. According to Robert May, the correct estimate for global species diversity is approximately 7 million species.
Key Points on Species Diversity
- Definition of Species Diversity: Species diversity refers to the variety of different species present in a given ecosystem or on the planet as a whole. It encompasses both the number of species (richness) and their relative abundance.
- Robert May’s Estimate: In his influential work, Robert May, an ecologist, proposed that the global species diversity is around 7 million species. This estimate includes all forms of life, including plants, animals, fungi, and microorganisms.
- Importance of Species Diversity:
- Ecosystem Stability: Higher species diversity contributes to ecosystem resilience and stability.
- Biodiversity Benefits: Diverse ecosystems can provide essential services, such as pollination, nutrient cycling, and climate regulation.
- Challenges in Estimation: Estimating the exact number of species is challenging due to:
- Undiscovered Species: Many species, especially in less-explored habitats like oceans and rainforests, remain unidentified.
- Taxonomic Issues: Misclassification and synonymy can complicate species counts.
- Conclusion: The figure of 7 million species, as proposed by Robert May, reflects a scientific consensus that balances current knowledge with the uncertainties inherent in biodiversity research. Understanding and protecting this diversity is crucial for maintaining ecological health and human well-being.
This knowledge is vital for students preparing for exams like NEET, as it emphasizes the significance of biodiversity in ecological studies.