Lecture 3

• Heritability


  Are some traits heritable (genetic)?
• Heritable traits in humans


  • Hair
  • Eye color
  • Height
• Non-heritable traits in humans

  • Injuries
• If a trait is at least partly heritable, then offspring tend to be similar to their parents for that trait
• Evolution in a population's heritable traits or gene pool over time


  1. Variation in heritable traits

  2. Traits affecting survival and/or reproduction

  3. Natural selection
• If speed is at least partly heritable


  The next generation will be faster
• If speed is not heritable

  There is natural selection but no evolution
• Evolution


  • Happens across generations
  • Driven by natural selection
• Natural selection


  • Happens within a generation
• Evolutionary processes


  • Genetic drift
  • Mutation
  • Natural selection
• Evolution by natural selection happens whenever there is variation in a heritable trait that affects survival and/or reproduction
• Coevolution


  Two or more species reciprocally affect each other's evolution