Chapter 3 - Biodiversity & Evolution

What Is Biodiversity and Why Is It Important?
  • The biodiversity found in genes, species, ecosystems and ecosystem processes is vital to sustaining life on earth
  • Biodiversity is a crucial part of the earth's natural capital
    • Species
      • set of individuals who can mate and produce fertile offspring
    • There are 8 million to 100 million species
    • 1.9 million identified
    • Unidentified are mostly in rain forests and oceans
    • Species diversity
    • Genetic diversity
    • Ecosystem diversity
      • Biomes: regions with distinct climate and species
    • Why is biodiversity important?

     

  • How does earth's life change over time?
  • Biological evolution by natural selection

  • Evolution by natural selection works through mutations and adaptations
  • Adaptation through natural selection has limits
    • Adaptive gene traits must precede change in the environmental conditions
    • Reproductive capacity
  • Three common myths about evolution through natural selection

  • Geologic processes affect natural selection
    • Tectonic plates affect evolution and the location of life on earth
    • Earthquakes
    • Volcanic eruptions
  • Earth is just right for life to thrive
    • Temperature range supports life
    • Orbit size creates moderate temperatures
    • Liquid water necessary for life
    • Rotation speed doesn't overheat surface
    • Size is right for gravity to keep atmosphere

How Do Speciation, Extinction and Human Activities Affect Biodiversity?

  • As environmental conditions change, the balance between formation of new species and extinction of existing species determines the earth's biodiversity
  • How do new species evolve?
    • Speciation
    • Geographic isolation (example)
    • Reproductive isolation
  • Extinction is forever
  • Extinction is a natural process, but
    • Humans profoundly affect rates of extinction
      • North America 10,000 years ago:
        • mammoths, camels, giant ground sloths, lions, sabre-toothed cats and various types of horses, antelope, bear and other large mammals
  • Endemic species
  • Background extinction
  • Mass extinction
  • Changing the genetic traits of populations
    • Artificial selection
    • Genetic engineering
    • Issues to consider
      • Ethics
      • Morality
      • Privacy issues
      • Harmful effects