Unit 5: Ecology and Environment

Chapter 3: Biodiversity and Conservation

Levels of Biodiversity

• Genetic Diversity: Variation of genes within a species (e.g., different varieties of rice and mango).
• Species Diversity: Variety of species in a region (richness and evenness).
• Ecosystem Diversity: Variety of ecosystems in a geographical area (e.g., deserts, rainforests, wetlands).

Patterns of Biodiversity

• Latitudinal Gradient: Species diversity decreases from the equator to the poles.
• Species-Area Relationship:
  • Species richness increases with explored area, up to a limit.
  • Equation: log S = log C + Z log A

Importance of Biodiversity

• Utilitarian Reasons:
  • Direct: Food, medicine, industrial products.
  • Indirect: Pollination, climate regulation, nutrient cycling.
• Ethical Reasons: Every species has an intrinsic value.
• Rivet Popper Hypothesis:
  • Analogy: Ecosystem is an airplane, species are rivets.
  • Losing species (rivets) weakens the ecosystem (airplane) and can lead to its collapse.

Causes of Biodiversity Loss (The Evil Quartet)

1. Habitat Loss and Fragmentation: The most important cause.
2. Over-exploitation: Harvesting resources faster than they can recover.
3. Alien Species Invasions: Non-native species outcompete native species.
4. Co-extinctions: The loss of one species leads to the loss of another dependent species.

Biodiversity Conservation

• In Situ (On-site) Conservation:
  • Protecting species in their natural habitats.
  • Methods: National Parks, Sanctuaries, Biosphere Reserves, Sacred Groves.
• Ex Situ (Off-site) Conservation:
  • Protecting species outside their natural habitats.
  • Methods: Botanical Gardens, Zoological Parks, Gene Banks, Cryopreservation.

Conservation Efforts

• Biodiversity Hotspots: Regions with high species richness and endemism under threat.
• Red Data Book (IUCN): Catalog of threatened species.
• International Conventions:
  • Earth Summit (Rio, 1992): Led to the Convention on Biological Diversity (CBD).
  • World Summit (Johannesburg, 2002): Pledged to reduce biodiversity loss.