Biodiversity Study Notes

Biodiversity Overview

• Definition: Biodiversity refers to the variability among living organisms on Earth, including variability within and between species and ecosystems.
• Importance:
  • Increases adaptability and survivability of species.
  • Maintains healthy ecosystems:
  • Each species plays a unique role.
  • Higher chance of organisms adapting to changing conditions (e.g., droughts, natural disasters).
  • Diverse ecosystems are more resilient and more likely to recover from environmental changes.

Measures of Biodiversity

1. Species Richness:
   • Total number of species within a specified region.
2. Genetic Diversity:
   • Total variety of genes within a single species.
3. Endemic Species:
   • Species that occur in a specific area and nowhere else in the world.
4. Ecosystem Diversity:
   • Total number of ecosystems in the region.
     • Unique ecosystems are those found only in certain regions, contributing to ecosystem diversity.

Global Biodiversity Patterns

• Increasing Biodiversity:
  • Commonly found closer to the equator due to:
  • More direct sunlight, precipitation, and chemical weathering.
  • Mountainous regions host diverse ecosystems due to:
  • Varied water sources, altitudes, and climates.
    • Mountains, covering 25% of Earth's land area, are home to 85% of amphibian, bird, and mammal species.

Adaptations and Their Role in Biodiversity

• Definition of Adaptations: Changes that help organisms survive in their environment.
• Types of Adaptations:
  • Physical Adaptations: Traits that enhance survival, such as:
  • Insulating fat in cold animals.
  • Camouflage through fur or feathers.
  • Plants' short root systems in cold climates.
  • Behavioral Adaptations: Actions that enhance survival, including:
  • Hibernation, migration, food storage, climbing for sunlight, avoiding predators, etc.

Invasive Species

• Definition: Species that are not native to a particular region and can disrupt local ecosystems.
• Characteristics of Invasive Species:
  • Lack natural predators in their new environment.
  • Can reproduce rapidly and adapt easily.
• Consequences:
  • Harm to native species and ecosystems.
• Examples:
  • Zebra Mussels: Introduced to the Great Lakes; they outcompete native species and clog water systems.
  • Cats on Marion Island: Introduced for pest control; led to decline of local seabird populations.
• Not all non-native species are harmful; some, like food crops, are beneficial.

Value of Biodiversity

• Removal of species can have drastic interconnected effects on ecosystems.
• Observed a ~70% decrease in global wildlife populations over the last 50 years due to climate change and habitat loss.
• Consequences of lower biodiversity include:
  • Increased vulnerability to pests and diseases.
  • Negative impact on food security (e.g., reduction of pollinators).
  • Economic implications tied to biodiversity loss (e.g., reduction in raw materials).

Endangered Species and Extinction

• Endangered Species: A species is classified as endangered if its population declines by 70% due to known causes or 50% if the cause is unknown.
• Main drivers of endangerment include habitat loss and decreased genetic variation.
• Extinction: The permanent disappearance of a species, linked to human activities.
• Present loss rate: ~1 species per million species annually, typically accelerated by human actions.

Drivers of Biodiversity Loss

1. Habitat Loss: Destruction of ecosystems affecting resources.
2. Invasive Species: Disruption of colonized ecosystems.
3. Overexploitation: Unsustainable harvesting leading to species depletion.
4. Pollution: Environment alteration exceeding its natural capacity.
5. Climate Change: Modification of climate due to greenhouse gas emissions.
   • Influenced by population growth, consumption rates, and resource efficiency.

Ethical Considerations

• Ethical responsibility towards preserving biodiversity:
  • Belief that species and ecosystems have inherent rights to exist.
  • Loss of biodiversity diminishes fascination and study of the environment.

Human Mitigation Efforts

• Legislation: 1973 US Endangered Species Act aims to protect threatened and endangered species and their habitats—99% on the list have survived.
• Establishment of natural preserves and national parks (e.g., Yellowstone National Park).