Chapter 12: The Origins of Biodiversity

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Chapter 12The Origins of Biodiversity

• Section 12-2
• Biodiversity

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Biodiversity

• imagine yourself on a journey upward from the
  center of the Earth, taken at the pace of a
  leisurely walk Edward O. Wilson
• p. 268

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Biodiversity

• Defined as the variety of living organisms, the
  genetic information they contain, and the
  biological communities in which they live
• Results from one adaptive radiation after another

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Biodiversity

• Three defined levels
• Ecosystem diversity
• Species diversity
• Genetic diversity

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Ecosystem Diversity

• Ecosystems are communities of organisms and their
  environments.
• Ecosystem diversity includes the variety of
  habitats, living communities, and ecological
  processes in the living world.

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Species Diversity

• Refers to the enormous variety of living
  organisms on Earth
• The number and variety of species in an ecosystem
  can profoundly influence that systems stability,
  productivity, and value to humans
• Presence or absence of a single species can
  change the whole ecosystem

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Genetic Diversity

• In general - refers to the sum total of all the
  different forms of genetic information carried by
  all organisms living on Earth today
• Within a species refers to the total variety of
  all alleles in the gene pool
• Variety can exist between groups of organisms
  living in different places, and even among
  individuals within populations

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Importance of Genetic Diversity

• Gives rise to inheritable variation, providing
  the raw material for evolution
• Without genetic diversity, natural selection
  would have nothing to act upon and species could
  not change

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Importance of Genetic Diversity

• Species MUST be able to change because of natural
  processes and human influence
• Genetic diversity is a result of millions of
  years of random mutation, natural selection, and
  genetic drift