Ecology

• Edward Wilson: 'Popularised the term 'Biodiversity''
• Types of Biodiversity

  • Genetic
  • Species
  • Ecological
• Genetic biodiversity


  Variations at the level of genes within the same species
• Species biodiversity


  Variety of species
• Ecological biodiversity


  Variety of ecosystems present in an area
• Ecosystem biodiversity

  • Species richness
  • Chemical Reserpine produced by Rauvolfia vamitoria
• Western Ghats have more varieties of amphibians compared to Eastern Ghats in India
• Coastal areas, deserts, and forests have high biodiversity
• IUCN (2004) has described 1.5 million species of plants and animals
• Robert May estimates 7 million species expected globally
• Composition of animal biodiversity

  • Insects
  • Crustacean
  • Mollusca
  • Invertebrates
  • Vertebrates
• Number of fungi species is more than the combined total of fishes, amphibians, reptiles, and mammals
• India has 2.4% of the world's land area but 8% of the world's species diversity
• India has 12 mega biodiversity hotspots, 45,000 species of plants, and 90,000 species of animals
• Patterns of Biodiversity

  • Maximum at the equator
  • Decreases with increasing latitude
  • More in areas with stable climate and high productivity
• Columbia near the equator has 1400 species of birds, New York has 105 species, and Greenland has 56 species
• Species-Area Relationship


  Species richness increases with increasing explored area, but only up to a limit
• The formula for the Species-Area Relationship is: log S = log C + z log A, where S is species richness, A is area, C is a constant, and z is the slope of the line
• The value of z is typically between 0.1-0.2 for small areas and 0.6-1.2 for entire continents
• Importance of species diversity in a stable community

  • Provides resistance to alien species invasion
  • Shows less year-to-year variation
  • Demonstrates higher productivity
• The "Rivet Popper Hypothesis" proposed by Paul Ehrlich states that loss of biodiversity reduces ecosystem productivity and stability
• According to the IUCN Red List (2004), 784 species are extinct
• Consequences of biodiversity loss

  • Reduced productivity
  • Increased environmental variability
• Main causes of biodiversity loss

  • Habitat loss and fragmentation
  • Over-exploitation
  • Alien species invasion
• Endemism (species found only in one place) leads to higher risk of extinction
• Loss of mutualistic species (e.g. host-parasite, plant-pollinator) can also lead to biodiversity loss
• Ex-situ conservation methods

  • Zoos
  • Botanical gardens
  • Seed banks
  • Cryopreservation
• India has 3 biodiversity hotspots: Western Ghats, Eastern Himalayas, and Indo-Burma
• India hosted the G20 summit in 2023 and the Rio de Janeiro Earth Summit in 1992 and the Johannesburg Summit in 2002
• 1000 varieties of mango and 5000 varieties of rice
• IUCN - International union of conservation of nature and natural resources ( 2004)
• scientists estimates 20-50 million species
• • Composition of global biodiversity
  • 70% animals
  • 22% plants
  • 8% other
• why diversity is more in tropics?

  • less seasonal variations
  • climate is stable
  • more sunlight is more productivity
  • less glaciation
• amazon forest - greatest biodiversity and lungs of the
• IUCN red list examples :

  • tiger ( bali, java, caspian)
  • dodo ( Mauritius)
  • quagga ( africa)
  • stellar cow
• over exploitation : dodo and stellar cow
• allien  species invasion :

  • water hyacinth- terror of bengal
  • lantana is shrub introduced in India
  • nile perch- a large predator fish
• why do we need to conserve?

  • narrow utilisation- lubricants and dye
  • broad utilisation - o2, co2 use
• bioprospecting : inspecting genetic and species level for economic importance