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.