Conservation of Biodiversity

Biodiversity as the Variety of Life

Definition: Biodiversity is the variety of life in all its forms, levels, and combinations.

  • Three levels of biodiversity:

    1. Ecosystem diversity – different habitats (e.g. coral reefs, deserts, forests).

    2. Species diversity – variety of species within ecosystems.

    3. Genetic diversity – variation within species (e.g. poodles vs Great Danes).

Current vs Past Levels of Biodiversity

  • Estimated 2–10 million eukaryotic species today.

  • Fossil evidence shows more species exist today than at any previous time in Earth’s history.

  • Some species may not yet be identified or may be classified differently due to taxonomic differences:

    • "Splitters" recognize more distinct species.

    • "Lumpers" group similar organisms together into fewer species.

Causes of Anthropogenic Species Extinction

The sixth mass extinction is human-caused (anthropogenic), unlike previous natural extinctions.

  • Major anthropogenic causes:

    • Overharvesting (e.g. poaching, hunting)

    • Habitat destruction

    • Invasive species

    • Pollution

    • Climate change

Case Studies:

  1. North Island Giant Moa (Dinornis novaezealandiae) – Hunted to extinction by Māori settlers in New Zealand.

  2. Caribbean Monk Seal (Neomonachus tropicalis) – Extinct due to overfishing and habitat loss.

  3. Local example (choose a familiar one from your region) – E.g., West African Black Rhino or Passenger Pigeon.

Causes of Ecosystem Loss

Ecosystems are being lost due to anthropogenic activities like agriculture, mining, urban expansion.

Ecosystem = Biotic (living) + Abiotic (non-living) components that interact.

Case Studies:

  1. Mixed Dipterocarp Forest in Southeast Asia – Lost due to logging and oil palm plantations.

  2. Aral Sea – Rivers diverted for irrigation led to a drastic drop in water level, destroying aquatic ecosystems.

Evidence for a Biodiversity Crisis

Evidence compiled by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES).

  • Types of evidence:

    • Habitat degradation

    • Declines in species range and population size

    • Loss of genetic diversity

  • Surveys need to be repeated and reliable, involving both expert and citizen scientists.

  • NOS Insight: Peer-reviewed evidence is verifiable. Citizen science offers benefits but must be methodologically careful.

Causes of the Current Biodiversity Crisis

  • Root cause: Human population growth.

  • Specific drivers:

    • Hunting & over-exploitation

    • Urbanization

    • Deforestation for agriculture

    • Pollution

    • Spread of invasive alien species, pests, and diseases due to global transport.

Several Approaches to Conservation

  • No single method is enough—a combination is required.

In Situ Conservation (in natural habitats):

  • Examples: Nature reserves, national parks.

  • Benefits: Maintains natural behaviors, evolutionary pressures, and biodiversity.

  • May require active management (e.g., removing invasive species).

Ex Situ Conservation (outside natural habitats):

  • Examples: Zoos, botanical gardens, seed banks.

  • Useful for critically endangered species.

  • May include captive breeding, germ plasm storage (sperm, egg, seed banks), and later reintroductions.

Other strategies:

  • Rewilding: Reintroducing species to restored habitats.

  • Reclamation: Restoring degraded ecosystems.

EDGE Species and Conservation Prioritization

  • EDGE = Evolutionarily Distinct and Globally Endangered.

    • Evolutionarily Distinct: Few or no close relatives; genetically unique.

    • Globally Endangered: High extinction risk across all habitats.

  • Focuses conservation efforts on species that are irreplaceable if lost.

  • Example: Pangolins, Axolotls, or certain rare amphibians.

NOS Insight:

  • Prioritizing species has ethical, political, environmental, social, and economic implications.

  • Must be carefully debated and justified.