Biodiversity and Conservation

Biodiversity

Amazing Diversity of Life

• Earth has an enormous variety of living organisms.
• There are:
  • Over 20,000 species of ants.
  • 300,000 species of beetles.
  • 28,000 species of fishes.
  • Nearly 20,000 species of orchids.
• Ecologists and evolutionary biologists study the significance of this diversity.

Questions About Diversity

• Why are there so many species?
• Did such diversity always exist?
• How did this diversity develop?
• How important is this diversity to the biosphere?
• How do humans benefit from this diversity?

15.1 Biodiversity

• Biodiversity exists at all levels of biological organization, from cells to biomes.
• Term popularized by sociobiologist Edward Wilson.

Types of Biodiversity

1. Genetic Diversity
   • High genetic variation within a single species.
   • Example: Rauwolfia vomitoria shows genetic variation in the Himalayas in terms of the chemical (reserpine) it produces.
   • India has:
     • Over 50,000 genetically different strains of rice.
     • 1,000 varieties of mangoes.
2. Species Diversity
   • Diversity at the species level.
   • Example: Western Ghats have more amphibian species than Eastern Ghats.
3. Ecological Diversity
   • Diversity at the ecosystem level.
   • Example: India has deserts, rainforests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows, offering greater ecosystem diversity compared to countries like Norway.

Importance of Biodiversity

• It took millions of years of evolution to develop this diversity.
• Current rates of species loss could deplete this diversity in less than two centuries.
• Conservation of biodiversity is crucial for survival and well-being on Earth.
• Biodiversity and its conservation are now vital international environmental issues.

How Many Species are there on Earth and How Many in India?

Total Species on Earth

• Recorded Species: About 1.5 million species of plants and animals have been described.
• Unknown Species: Many species are yet to be discovered, especially in tropical regions.
• Estimates: Estimates of total species range from 20 to 50 million. Robert May’s estimate is about 7 million.

Biodiversity Distribution

• Animals: Over 70% of all recorded species.
  • Insects: Make up more than 70% of animal species. 7 out of every 10 animals are insects.
• Plants: Including algae, fungi, bryophytes, gymnosperms, and angiosperms, they comprise no more than 22% of total species.
• Fungi: More species than the combined total of fishes, amphibians, reptiles, and mammals.

Prokaryotes

• Unknown Count: Exact number unknown due to difficulty in identifying microbial species.
• Potential Diversity: If biochemical or molecular criteria are used, diversity might be in millions.

Biodiversity in India

• Land Area: India has only 2.4% of the world’s land area.
• Species Diversity: Holds 8.1% of global species diversity.
  • Plants: About 45,000 recorded species.
  • Animals: About 90,000 recorded species.
• Undiscovered Species: Estimated to be more than 100,000 plant species and 300,000 animal species still to be discovered.

Challenges in Discovering Species

• Manpower and Time: Requires a vast number of trained taxonomists and significant time.
• Extinction Threat: Many species may become extinct before being discovered.

Key Points

• Biodiversity: Rich and diverse, particularly in tropical regions.
• India: One of the 12 mega diversity countries in the world.
• Conservation: Urgent need to catalog and protect biodiversity before it’s lost.

Patterns of Biodiversity

Latitudinal Gradients

• Uneven Distribution: Diversity of plants and animals varies worldwide.
• General Trend: Species diversity decreases from the equator to the poles.
  • Examples:
    • Colombia (near equator): ~1,400 bird species.
    • New York (41° N): 105 bird species.
    • Greenland (71° N): 56 bird species.
    • India (tropical): >1,200 bird species.
    • Amazon Rainforest:
      • 40,000 plant species.
      • 3,000 fish species.
      • 1,300 bird species.
      • 427 mammal species.
      • 427 amphibian species.
      • 378 reptile species.
      • 125,000 invertebrates.
      • ~2 million undiscovered insect species.
• Reasons for High Tropical Diversity:
  • Time: Tropics undisturbed for millions of years, allowing long evolutionary time.
  • Environment: Less seasonal, more constant, promotes niche specialization.
  • Solar Energy: More solar energy, higher productivity, leading to greater diversity.

Species-Area Relationships

• Humboldt’s Observation: Species richness increases with explored area, but up to a limit.
• Relationship: Rectangular hyperbola, straight line on a logarithmic scale.
  • Equation: log S = log C + Z log A
    • S: Species richness.
    • A: Area.
    • Z: Slope of the line (0.1 to 0.2 for various taxa).
    • C: Y-intercept.
• Steeper Slopes for Larger Areas:
  • Large Areas: Slopes are steeper (Z values 0.6 to 1.2).
  • Example: Frugivorous birds and mammals in tropical forests have a slope of 1.15.

Key Points

• Biodiversity: Higher in tropics than temperate or polar areas.
• Species-Area Relationship: Species richness increases with area, more noticeable in larger areas.
• Examples and Observations: Richness patterns observed by Humboldt and others.

The Importance of Species Diversity to the Ecosystem

Does Species Number Matter?

• Question: Does the number of species in a community affect ecosystem function?
• Belief: More species = more stable communities.

What is Stability?

• Stable Community:
  • Consistent productivity year to year.
  • Resistant or resilient to disturbances (natural or man-made).
  • Resistant to invasions by alien species.

David Tilman’s Experiments

• Findings:
  • More species = less variation in total biomass year to year.
  • Higher diversity = higher productivity.

Importance of Biodiversity

• Ecosystem Health: Rich biodiversity is essential.
• Human Survival: Crucial for our survival on the planet.

Loss of Species

• Concern: Rapid loss of species is alarming.
• Example Questions:
  • Would Western Ghats be less functional if a tree frog species is lost?
  • Does our quality of life change if ant species drop from 20,000 to 15,000?

Rivet Popper Hypothesis (Paul Ehrlich)

• Analogy: Ecosystem = airplane, species = rivets.
  • Rivets Removed: Initially, flight (ecosystem) is safe.
  • More Rivets Removed: Plane (ecosystem) becomes weak and unsafe.
  • Critical Rivets: Loss of key species (rivets on wings) is more serious than less important ones (rivets on seats or windows).

Key Points

• Species Diversity: Important for ecosystem stability and function.
• Experiments: Show more species can lead to more stable and productive ecosystems.
• Biodiversity Loss: Poses a serious threat to ecosystems and human survival.

Loss of Biodiversity

Declining Biological Wealth

• Human Activities: Main cause of species loss.
• Examples:
  • Extinction of >2,000 native bird species due to human colonization of Pacific Islands.
  • IUCN Red List (2004): 784 species extinct in last 500 years (338 vertebrates, 359 invertebrates, 87 plants).
  • Recent extinctions: dodo, quagga, thylacine, Steller’s sea cow, and three tiger subspecies.

Current Extinctions

• Vulnerable Groups: Amphibians more at risk.
• Threatened Species: >15,500 species worldwide.
  • 12% of all bird species.
  • 23% of all mammal species.
  • 32% of all amphibian species.
  • 31% of all gymnosperm species.

Historical Context

• Mass Extinctions: Five episodes before humans.
• Sixth Extinction: Currently in progress, faster rates due to human activities.
  • Current extinction rate: 100 to 1,000 times faster.
  • Prediction: Nearly half of all species may disappear in next 100 years.

Consequences of Biodiversity Loss

• Decline in Plant Production.
• Lowered Resistance: To environmental changes like drought.
• Increased Variability: In ecosystem processes (plant productivity, water use, pest and disease cycles).

Causes of Biodiversity Loss: The Evil Quartet

1. Habitat Loss and Fragmentation
   • Main Cause: Leading to extinctions.
   • Tropical Rainforests: Dramatic examples, cover reduced from 14% to 6% of earth’s surface.
   • Amazon Rainforest: Rapid destruction for agriculture and cattle raising.
   • Fragmentation: Large habitats broken into small fragments, affecting species requiring large territories or migratory habits.
2. Over-exploitation
   • Human Greed: Leads to overuse of resources.
   • Historical Extinctions: Steller’s sea cow, passenger pigeon.
   • Current Threat: Overharvesting marine fish populations.
3. Alien Species Invasions
   • Invasive Species: Introduced species causing decline/extinction of native species.
   • Examples:
     • Nile perch in Lake Victoria: Extinction of 200 cichlid fish species.
     • Invasive weeds: Carrot grass, Lantana, water hyacinth.
     • African catfish: Threat to native catfishes in rivers.
4. Co-extinctions
   • Linked Extinctions: Species dependent on each other.
   • Examples:
     • Host fish and its parasites.
     • Coevolved plant-pollinator mutualisms.

Key Points

• Human Impact: Major cause of current biodiversity loss.
• Preventive Measures: Urgent need to address habitat loss, over-exploitation, alien species invasions, and co-extinctions.

Biodiversity Conservation

Why Should We Conserve Biodiversity?

Reasons to Conserve Biodiversity:

• Narrowly Utilitarian
  • Economic Benefits: Direct benefits from nature like food (cereals, pulses, fruits), firewood, fibre, construction material, industrial products (tannins, lubricants, dyes, resins, perfumes).
  • Medicinal Importance: Over 25% of market drugs from plants. 25,000 plant species used in traditional medicines.
  • Bioprospecting: Exploring biodiversity for products of economic importance can bring huge benefits.
• Broadly Utilitarian
  • Ecosystem Services: Biodiversity helps in ecosystem services.
  • Oxygen Production: Amazon forest produces 20% of earth’s oxygen. Value of this service is immense.
  • Pollination: Bees, birds, bats help in pollination essential for fruits and seeds. Costly to replicate without natural pollinators.
  • Aesthetic Pleasures: Enjoyment from nature like walking in woods, seeing spring flowers, hearing birds. Priceless experiences.
• Ethical
  • Intrinsic Value: Every species has its own value, regardless of economic use.
  • Moral Duty: Responsibility to care for all species and preserve them for future generations.

Key Points:

• Economic: Direct and indirect benefits from biodiversity.
• Ecosystem Services: Essential roles like oxygen production and pollination.
• Ethical: Moral responsibility to protect and conserve all species.

How Do We Conserve Biodiversity?

In Situ Conservation

• Protecting Entire Ecosystems: Save the whole forest to save the tiger.
• Biodiversity Hotspots: Areas with high species richness and endemism.
  • Examples: Western Ghats, Sri Lanka, Indo-Burma, Himalaya.
  • Coverage: Less than 2% of earth’s land but high species number.
  • Impact: Protecting hotspots can reduce mass extinctions by 30%.
• Protected Areas in India:
  • Biosphere Reserves: 14
  • National Parks: 90
  • Wildlife Sanctuaries: 448
• Sacred Groves: Protected by cultural traditions.
  • Locations: Khasi and Jaintia Hills (Meghalaya), Aravalli Hills (Rajasthan), Western Ghats (Karnataka and Maharashtra), Sarguja, Chanda, Bastar (Madhya Pradesh).

Ex Situ Conservation

• Special Settings for Endangered Species: Zoological parks, botanical gardens, wildlife safari parks.
• Advanced Techniques:
  • Cryopreservation: Preserve gametes of threatened species.
  • In Vitro Fertilization: Fertilize eggs outside the body.
  • Tissue Culture: Propagate plants.
  • Seed Banks: Store seeds of important plants for long periods.

Global Efforts

• Convention on Biological Diversity (1992): Held in Rio de Janeiro, urged all nations to conserve biodiversity.
• World Summit on Sustainable Development (2002): Johannesburg, 190 countries committed to reducing biodiversity loss by 2010.

Key Points:

• In Situ: Protecting species in their natural habitats.
• Ex Situ: Protecting species outside their natural habitats.
• Global Responsibility: Conservation is a collective duty of all nations.

Chapter Summary:

• Life on Earth started around 3.8 billion years ago.
• Biodiversity includes diversity at genetic, species, and ecosystem levels.
• Over 1.5 million species are known, but around 6 million species may still be undiscovered.
• Majority of named species are animals, with insects being the most abundant.
• Fungi have more species than all vertebrates combined.
• India is one of the 12 mega diversity countries, with about 45,000 plant species.
• Species diversity is highest in the tropics and decreases towards the poles.
• Tropics have more evolutionary time, stable environments, and higher solar energy, leading to greater productivity.
• Species richness is influenced by the area of a region.
• Diverse communities tend to be less variable, more productive, and resistant to invasions.
• Current extinction rates, largely due to human activities, are 100 to 1000 times higher than past rates.
• Over 700 species have gone extinct recently, with over 15,500 species currently facing extinction.
• Causes include habitat loss, overexploitation, biological invasions, and co-extinctions.
• Biodiversity is crucial for human survival, providing direct benefits like food and indirect benefits through ecosystem services.
• Conservation can be in situ (protecting species in their natural habitat) or ex situ (protective maintenance in zoological parks and botanical gardens).
• 34 biodiversity hotspots have been identified globally, including three covering India’s rich biodiversity regions.
• India’s conservation efforts include 14 biosphere reserves, 90 national parks, over 450 wildlife sanctuaries, and sacred groves.
• Ex situ conservation methods include in vitro fertilization, tissue culture propagation, and cryopreservation of gametes.