Biodiversity and Conservation

About this unit

Biodiversity is the variety of life at every level of biological organisation. This unit explains the levels of biodiversity (genetic, species and ecological), how species are distributed on earth, especially the latitudinal gradient and the species–area relationship, and why biodiversity matters for ecosystem stability. It then examines the causes of biodiversity loss, the reasons for conserving it, and the in situ and ex situ strategies used to protect it, with special reference to India as a megadiversity country.

Key ideas

• Genetic, species and ecological diversity are the three levels of biodiversity.
• Species diversity generally decreases from the equator towards the poles.
• The species–area relationship is log S = log C + Z log A.
• The "evil quartet": habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions.
• Conservation arguments are narrowly utilitarian, broadly utilitarian and ethical.
• In situ conservation protects species in their natural habitat; ex situ conservation protects them outside it.

How to prepare

Memorise standard examples: Rauwolfia vomitoria for genetic diversity, the Nile perch in Lake Victoria for alien invasions, and the extinct dodo, quagga, thylacine and Steller's sea cow. Learn the three hotspots that include parts of India and the regions known for sacred groves. Practise questions on the slope Z and the rivet popper hypothesis.