Biodiversity and Conservation

• Introduction to Biodiversity

  • Definition: Combined diversity at all levels of biological organization
  • Term popularized by: Edward Wilson
  • Three hierarchical levels:
    • Genetic Diversity: Diversity within a single species (e.g., Rauwolfia vomitoria variations)
    • Species Diversity: Diversity at the species level (e.g., Amphibian species richness in Western Ghats vs Eastern Ghats)
    • Ecological Diversity: Diversity at the ecosystem level (e.g., Deserts, rain forests, mangroves in India)

• Magnitude of Biodiversity

  • Global Estimates:
    • Total plant and animal species described: > 1.5 million (IUCN, 2004)
    • Conservative estimate by Robert May: About 7 million species globally
    • Animal proportion: > 70% (Insects form the most species-rich taxonomic group, > 70% of animals)
  • India's Biodiversity:
    • Land area: 2.4% of the world's land area
    • Global species diversity: 8.1% (a megadiversity country)
    • Plant species: ~45,000; Animal species: ~90,000

• Patterns of Biodiversity

  • Latitudinal Gradients:
    • Species diversity decreases from equator to poles (tropics harbor more species than temperate/polar regions)
    • Reasons: Tropics have more evolutionary time, constant/predictable environment, and higher solar energy
  • Species-Area Relationships:
    • Given by German naturalist Alexander von Humboldt
    • Richness increases with explored area, but up to a limit
    • Equation: $\log S = \log C + Z \log A$
      • $S$ = Species richness, $A$ = Area, $C$ = Y-intercept, $Z$ = Slope of line (regression coefficient)
      • Slope ($Z$-value) is generally 0.1 to 0.2, but for very large areas (like continents), $Z$ is 0.6 to 1.2

• Importance of Biodiversity

  • Ecological Stability:
    • Communities with more species tend to be more stable (David Tilman's plot experiments)
    • Essential for ecosystem health and productivity
  • The 'Rivet Popper' Hypothesis:
    • Proposed by Paul Ehrlich
    • Compares ecosystem to an airplane; loss of key species (rivets) poses a serious threat to flight safety
  • Ecosystem Services:
    • Oxygen production, pollination, flood control, climate regulation, aesthetic/spiritual value

• Loss of Biodiversity

  • Extinction Types:
    • Natural (slow) vs. Mass Extinction (current 6th extinction is human-driven and 100-1000 times faster)
  • The Evil Quartet (Causes of biodiversity loss):
    • Habitat Loss and Fragmentation: Most important cause (e.g., Tropical rainforests reducing from 14% to 6% of earth's land)
    • Over-exploitation: Overuse of resources (e.g., Steller's sea cow, Passenger pigeon extinction)
    • Alien Species Invasions: Introduction of non-native species causing decline of indigenous species (e.g., Nile perch, Water hyacinth, Parthenium)
    • Co-extinctions: Extinction of one species leads to obligate partner's extinction (e.g., Host fish and parasites)

• Biodiversity Conservation

  • Why Conserve?
    • Narrowly Utilitarian: Direct economic benefits (food, drugs, industrial products, bioprospecting)
    • Broadly Utilitarian: Ecosystem services (pollination, climate regulation, aesthetic value)
    • Ethical: Moral duty to protect every species sharing the planet
  • How to Conserve?
    • In situ (On-site) Conservation:
      • Protecting the whole ecosystem
      • Hotspots: Regions with high endemism and species richness (34 global hotspots; 3 in India: Western Ghats, Himalayas, Indo-Burma)
      • Protected Areas in India: Biosphere Reserves (18), National Parks (106+), Wildlife Sanctuaries (500+), Sacred Groves
    • Ex situ (Off-site) Conservation:
      • Protecting species outside their natural habitats
      • Examples: Zoological parks, Botanical gardens, Wildlife safari parks, Cryopreservation, Gene banks, pollen banks