Biodiversity and Conservation

Syllabus Unit: Ecology and Environment

Why it matters

Chapter overview

Biodiversity is the sum of all genetic, species and ecosystem-level variety on Earth, and it is being lost faster today than at almost any point in geological history. This topic defines biodiversity's three levels, the global patterns (like the latitudinal gradient) and ecosystem services that make it worth protecting, the specific human-driven causes of its loss, and the in-situ and ex-situ strategies — including India's own biodiversity hotspots — used to conserve what remains.

Biology Syllabus Ecology and Environment 12%–14% weightage

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Genetic DiversityVariation within one species

Species DiversityVariety of species in a region

Ecological DiversityVariety of ecosystems/habitats

1Concept & Levels of Biodiversity

Biodiversity is not one number — it spans three distinct levels, from the genes inside a single species to the diversity of whole ecosystems.

Learning Objectives

Define biodiversity and name the scientist who popularised the term (E.O. Wilson).
Distinguish genetic diversity, species diversity and ecological (ecosystem) diversity with an example of each.
State the approximate number of species described globally versus the estimated true total.
Explain why genetic diversity within a species matters for its long-term survival.

Key Terms

BiodiversityThe total variety of life on Earth, encompassing genetic, species and ecosystem-level variation; the term was popularised by E.O. Wilson.

Genetic DiversityVariation in genes/alleles within a single species, e.g. the thousands of genetically distinct rice and mango varieties in India.

Species DiversityThe variety and relative abundance of different species within a region — the most commonly measured level of biodiversity.

Ecological DiversityThe variety of ecosystems (deserts, forests, wetlands, coral reefs) and their ecological processes within a geographic area.

**Biodiversity** — a term popularised by American biologist **Edward O. Wilson** — refers to the total variety of life on Earth at every level of biological organisation, not just the number of species.

Three levels of biodiversity

Genetic diversity — variation in genes/alleles within a single species; India alone has over 50,000 genetically distinct strains of rice and 1,000 varieties of mango, giving the species resilience against disease and changing conditions.
Species diversity — the variety of species in a region, most commonly what people mean by 'biodiversity'; measured as species richness (number of species) and species evenness (relative abundance).
Ecological (ecosystem) diversity — the variety of habitats, communities and ecological processes (forests, deserts, wetlands, coral reefs) present in a larger geographic area, e.g. India shows far greater ecosystem diversity than a Scandinavian country of similar size.

Key PointAbout 1.5-1.8 million species have been formally described so far, but estimates of the true global total range from 7 million to over 20 million — most species, especially insects and microbes in tropical regions, remain undiscovered.

Genetic diversity matters beyond aesthetics: a genetically uniform species/crop is far more vulnerable to a single disease or environmental shock wiping it out entirely, which is exactly why crop gene banks preserve wild and traditional varieties.