Biodiversity and Conservation - SL

3.1 Biodiversity and Evolution

• Biodiversity exists at three levels: species, habitat, and genetic diversity.

• Low diversity can occur in natural, ancient, and unpolluted sites.

Types of Biodiversity

• Genetic Diversity: Range of genetic material in a species population.- Example: Mauritian Pink Pigeon with a small gene pool.

• Species Diversity:- Species Richness: Number of species in a community.

  • Species Evenness: Similarity of population sizes among species.

• Communities and Diversity Indices:- Compared using indices like Simpson's Index.

  • Low diversity may indicate pollution or recent colonization.

  • Repeat investigations over time to identify changes.

• Measuring Species Diversity:- Simpson’s Reciprocal Index (D) used to quantify diversity: D = \frac{N(N-1)}{\Sigma n(n-1)} where N is the total number of individuals and n is the number of individuals of a single species.
  

  Example: Fires started by Australian Aborigines can improve biodiversity.

• Genetic Diversity:- Small populations have lower genetic diversity.

  • Different populations need conservation to maximize genetic diversity.

  • Humans have high genetic diversity due to global distribution.

• Habitat Diversity:- Range of different habitats in an ecosystem or biome.

  • Tropical rainforests have high habitat diversity; tundra has lower.

• Resilience of Ecosystems:- Diversity contributes to the ability of a system to maintain equilibrium.

  • High species diversity leads to complex food webs.

  • Greater genetic diversity enhances survival during adversity.

• Biodiversity as an Indicator:- High biodiversity often equates to high ecosystem health.

  • Diversity from pioneer species colonizing bare areas may not indicate health.

Evolution

• Evolution is cumulative change in heritable characteristics.

• Natural selection drives evolutionary change.

• Process involves variation, overproduction, competition, and adaptation.

• Individuals with advantageous genes pass them on, increasing frequency over generations.

• Speciation is the generation of new species through evolution when populations become isolated and adapt differently.

• Knowledge of biodiversity is needed for effective conservation management.

3.2 Human Impact on Biodiversity

• Direct threats: Overharvesting, poaching, illegal pet trade.

• Indirect threats: Habitat loss, climate change, pollution, invasive species.

• Overexploitation: Increased by human population growth and technology.

• Poaching: Illegal killing of wildlife, worth billions annually.

• Illegal Pet Trade: Harvesting animals for exotic pets.

• Pollution: Degrades habitats through pesticides, oil spills, emissions, and eutrophication.

• Loss of Habitat: Major cause of biodiversity loss, leading to fragmentation.

• Fragmentation: Isolates habitats, creates edge effects, reduces genetic diversity.

• Climate Change:

  • Disrupts coral reefs, shifts species towards the poles, causes ocean acidification.

• Introducing Non-Native Species:

  • Can upset ecosystems.
    

    Examples include rhododendrons, Dutch Elm disease, rabbits and cane toads in Australia.

• Multiple human impacts amplify effects.

• Invasive alien species reduce biodiversity through competition, predation, and disease.

• Invasive Alien Species - Arrival:

  • Ballast water discharge, hitchhiking on transportation, intentional introduction, release of pets/plants, aquaculture, enhanced natural dispersal, escape from biological control efforts.

• IUCN Red List: Assesses global conservation status based on population size, rate of change, breeding potential, geographic range, and known threats.

• IUCN Red List Categories: Extinct (EX), Extinct in the Wild (EW), Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), Data Deficient (DD), Not Evaluated (NE).

• Key Differences in Perspectives:

  • Government, NGOs, and Individuals

  • Case Studies:

  • Tiger (Endangered)

  • Golden Lion Tamarin (Recovered)

  • Dodo (Extinct)

• Tragedy of the Commons: Overexploitation of shared resources due to individual self-interest.

  • Example: Newfoundland Cod Fishery collapse.

• The Great Pacific Garbage Patch is waste in international waters.

3.3 Conservation and Regeneration

• Arguments for species and habitat preservation: aesthetic, ecological, economic, ethical, social.-

  • Ecological: important for ecosystem services

  • Economic: Focuses on the value of ecotourism, genetic resources and commercial considerations of natural capital.

• Biorights are species' rights to exist, humans should act as stewards.

• Species-based conservation (ex situ) vs. Habitat-based conservation (in situ).

• Species-Based Conservation- CITES (Convention on International Trade in Endangered Species):

  • International agreement regulating trade in endangered species to prevent overexploitation.

  • Provides a framework for countries to work together to protect vulnerable species.

  • Focuses on ensuring that international trade does not threaten the survival of species in the wild.

  • Utilizes permits and certificates to authorize trade, ensuring sustainability.

  • Effectiveness depends on member countries' enforcement and compliance.

  • Captive breeding programs in zoos can help reintroduce species.

  • Botanical gardens and seed banks preserve plant species.

• Habitat-Based Conservation- Creating nature reserves and national parks.

  • Key considerations when designing protected nature areas:

    • Size: Larger reserves are typically better as they can support larger populations and more diverse ecosystems.

    • Shape: Compact, circular shapes are preferred to minimize edge effects.

    • Connectivity: Corridors between reserves allow for species migration and gene flow.

    • Proximity: Clustered reserves can function as a network, enhancing overall conservation value.

    • Buffer Zones: Areas surrounding reserves that have limited human activity to protect the core area.

    • Keystone species have crucial roles in ecosystems.

    • Flagship species are charismatic species used to raise conservation funds.

• Convention on Biological Diversity (CBD): UN treaty for conservation and sustainable use of biodiversity.

• Rewilding restores ecosystems by reinstating natural processes. Rewilding Methods include: *Reintroduction of Apex Predators- Reintroduction of keystone species

  *Re-establishment of habitat connectivity over large areas

  *Cessation of agriculture and resource harvesting

  *Minimisation of human influence

  *Ecological management

• Resilience of Ecosystems:- Diversity contributes to the ability of a system to maintain equilibrium.

  • Resilience is the ability of an ecosystem to recover from disturbances and return to its original state.

  • Factors influencing resilience include species diversity, genetic diversity, habitat diversity, and the presence of keystone species.

  • Ecosystems with high resilience are better able to withstand environmental changes and human impacts.

  • Conservation efforts often focus on enhancing the resilience of ecosystems to ensure their long-term survival.

  • High species diversity leads to complex food webs.

  • Greater genetic diversity enhances survival during adversity.

• Biodiversity planetary boundary can be improved through conservation and regeneration at different levels.

• Choice of conservation strategies is influenced by environmental perspectives and value systems.

• Successful projects require community support, adequate funding, education, legislation, environmental justice, and research.

• Important note – 9 mark essays are the hardest part of the external exam.