13Class 12 Biology
Biodiversity and Conservation short notes
Short notes on biodiversity patterns, why it matters, why it's being lost, and how it's conserved. The numbers about India get asked frequently.
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Biodiversity
- Edward Wilson popularised the term. It exists at genetic, species and ecological levels.
- India has about 2.4% of the world's land, and about 8.1% of its species diversity.
- India is one of 12 mega-diversity countries.
- Diversity falls from the equator to the poles.
- Species-area relationship: log S = log C + Z log A, from Humboldt.
- Paul Ehrlich's rivet popper hypothesis shows how species loss weakens an ecosystem.
Loss
- The IUCN Red List tracks threatened species.
- The 'Evil Quartet' causes loss: habitat loss and fragmentation, over-exploitation, alien species and co-extinctions.
- Habitat loss is the biggest cause.
- Examples of alien species include Nile perch in Lake Victoria, and of over-exploitation the Steller's sea cow.
Conservation
- In situ: national parks, sanctuaries, biosphere reserves, hotspots and sacred groves.
- There are 34 biodiversity hotspots worldwide, three covering India: Western Ghats-Sri Lanka, Indo-Burma and the Himalaya.
- Ex situ: zoos, botanical gardens, seed banks and cryopreservation.
- The Convention on Biological Diversity came from the 1992 Rio Earth Summit.
Where students slip up
- Mixing up in situ and ex situ methods. Zoos are ex situ.
- Saying hotspots are all in the tropics, or that India has just one. Three cover India.
- Forgetting Z's usual range is 0.1 to 0.2, and is steeper for whole continents.
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