Biology 242: Lecture 9Spring 2001

Genetic Basis of Variation

  1. Heritable variation provides the raw material for natural selection

  2. Genetic basis of variation
    1. How extensive is genetic variation within and between populations?
      1. Not all variation is heritable
      2. Polymorphism
      3. Geographical variation
    2. How is genetic variation generated?
      1. Mutation
      2. Sexual recombination
    3. How is genetic variation preserved?
      1. Diploidy
      2. Balanced polymorphism
        1. Heterozygote advantage
        2. Hybrid vigor
        3. Patchy environments
        4. Frequency-dependent selection
    4. Is all genetic variation adaptive?

  3. Adaptive evolution
    1. Fitness
    2. What does selection act on?
    3. Modes of natural selection
      1. Stabilizing selection
      2. Directional selection
      3. Diversifying selection
    4. Sexual selection
    5. Does evolution fashion perfect organism?
      1. Historical constraints
      2. Adaptations are often compromises
      3. Not all evolution is adaptive
      4. Selection can only edit variations that exist


"It isn't the load that weighs us down--it's the way we carry it."
Apples of Gold