Biodiversity is where ecology turns into policy. This chapter covers what biodiversity is, where it is concentrated, why it is being lost, and the tools India and the world use to conserve it.

What UPSC asks

Prelims: IUCN Red List categories and which of them count as “threatened”; biodiversity hotspot criteria and the hotspots that cover parts of India; in-situ versus ex-situ methods; invasive species; the Biological Diversity Act, 2002 and its three-tier institutions; global targets such as the Kunming-Montreal framework.
Mains GS III: causes and consequences of biodiversity loss, community-based conservation, access and benefit sharing, and the balance between development and conservation.

Key sub-topics

Sub-topic	What to master
Levels and patterns	Genetic, species, ecosystem diversity; alpha, beta, gamma; latitudinal gradient; species–area relationship
Where biodiversity is	Megadiverse countries; the hotspot criteria; India’s four hotspots
Measuring threat	IUCN Red List categories and criteria
Threats	Habitat loss, invasive species, pollution, over-exploitation, co-extinction
Conservation	In-situ, ex-situ, sacred groves, gene banks
Law and institutions	Biological Diversity Act, 2002 (amended 2023); NBA, SBBs, BMCs; People’s Biodiversity Registers

Protected areas and the Wildlife (Protection) Act are covered separately in Protected Areas and Wildlife; the Convention on Biological Diversity and its protocols are in International Environmental Conventions.