Last reviewed 4 Nov 2026 · 2 min read
1. Meaning
DefinitionBiodiversity
The variety and variability of life on Earth — within species, between species and of ecosystems. The term "biological diversity" was popularised by E. O. Wilson (1980s); the Convention on Biological Diversity (1992) gives the standard definition.
2. Three levels
| Level | Meaning | Example |
|---|---|---|
| Genetic diversity | Variation of genes within a species | Thousands of rice varieties in India; different breeds of cattle |
| Species diversity | Variety of species in an area — richness (number) and evenness (relative abundance) | Western Ghats have more amphibian species than the Eastern Ghats |
| Ecosystem diversity | Variety of habitats, communities and ecological processes | Forests, grasslands, deserts, wetlands, mangroves, coral reefs in India |
Spatial measures (R. H. Whittaker)
| Measure | Meaning |
|---|---|
| Alpha (α) diversity | Diversity within a single community or habitat |
| Beta (β) diversity | Change in species between communities along a gradient |
| Gamma (γ) diversity | Total diversity of a large region (landscape) |
- Diversity indices combine richness and evenness — Shannon–Wiener index and Simpson's index.