IBESS Topic 3.2: Origins of Biodiversity

Overview

• Focus: Origins of Biodiversity under Topic 3: Biodiversity and Conservation.
• Key concepts: Species diversity, habitat diversity, genetic diversity.
• Primary ideas:
  1. Evolution: Gradual change in genetic character via natural selection.
  2. Environmental changes drive evolution and diversity.
  3. Historical mass extinction events.

Evolution

• Defined: Gradual change in gene pool over time; cumulative change in heritable characteristics.
• Mechanism: Natural selection.
  • Variation: Necessary for natural selection to occur.
  • Sources:
    • Genetic mutation.
    • Meiosis and random fertilization.

Natural Selection

• Defined: Mechanism by which individuals better suited to their environment survive and reproduce.
• Example Mechanisms:
  • Variation within species.
  • Competition for resources.
  • Genetic advantage and survival.
  • Reproduction of the fittest.
  • Examples: Arizona pocket mouse, peppered moth, antibiotic resistance in bacteria.

Speciation

• Definition: Formation of new species from isolated populations.
• Causes of Isolation:
  • Geographical, behavioral, genetic, or reproductive barriers.
  • Examples: Grand Canyon squirrels, Darwin’s finches.

Environmental Change and Evolution

• Environmental factors lead to challenges and drive speciation.
  • Examples: Colorado potato beetle, peppered moth adaptation.
• Role of Tectonic Plates:
  • Movement causes land barriers/bridges, climatic variation.
  • Historical plate movements (e.g., Pangea) influenced evolution.

Evidence of Evolution

• Fossil records: Show transitions (e.g., fish to amphibians).
• DNA studies: Indicate common ancestors.
• Comparative anatomy: Homologous structures.

Mass Extinctions

• Defined: Events causing rapid loss of species.
• Historical occurrences: Five major events (e.g., meteor impacts, tectonic movements).
• Current sixth extinction: Human-caused, rapid rate (Anthropocene).

Concluding Notes

• Evolution driven by natural selection and environmental changes.
• Speciation results from isolation and adaptation.
• Biodiversity influenced by tectonic movements and mass extinctions.

Additional Resources

• Presentation adapted from William Green's site, "The Amazing World of Science with Mr. Green."
• Additional insights from Mr. Dave Hoover's YouTube channel, IBESS textbooks and Cognity online resources.