Study Notes on Biodiversity, Evolution, and Extinction

Biodiversity

  • Biodiversity refers to the variety of all life on Earth, including microbial, protists, plants, fungi, and animals.

  • Approximately 1.5 million species have been described, with estimates suggesting up to 10 million exist.

  • Most species are located in tropical rain forests and coral reefs.

Key Terms in Biodiversity

  • Endemic Species: Found only in one region; high extinction risk.

  • Threatened Species: Likely to become endangered.

  • Endangered Species: In danger of extinction throughout its range.

  • Extirpated Species: Locally extinct in certain areas but exist elsewhere.

  • Extinct Species: No longer exists anywhere.

Factors Threatening Biodiversity

  • Major threats driving species loss:

    • Habitat destruction/fragmentation

    • Invasive species

    • Overharvesting

    • Disruption of ecological interactions

    • Pollution

Biologists' Concerns About Biodiversity Loss

  • 69% decline in populations of birds, mammals, fish, reptiles, and amphibians since 1970.

  • Loss of biodiversity impacts ecosystem services, health, and genetic diversity, crucial for food, medicine, and ecosystem capital.

Conservation Strategies

  • Identify biodiversity hot spots for conservation efforts.

  • Focus on areas with high concentrations of endemic and endangered species.

  • Apply ecological understanding for establishing protected areas.

Biological Evolution

  • Evolution involves changes in genetic makeup over time, explaining adaptation and diversity.

  • Genetic variation is critical for survival and adaptation; mechanisms include genetic drift, bottleneck effects, and founder effects.

  • Natural selection, proposed by Darwin, is the process where favorable traits become more common.

Speciation and Extinction

  • Speciation: The emergence of new species through natural selection, leading to biodiversity.

    • Types of speciation include allopatric (due to physical barriers) and sympatric (within the same area).

  • Extinction: Disappearance of species; occurs when species cannot adapt quickly enough to changes.

    • Background extinction occurs slowly, while mass extinctions happen suddenly (e.g., asteroid impacts).

    • The current 6th mass extinction is driven by human impacts such as habitat destruction and climate change.