Biology 338: Lecture 14Spring 1997

Sex/Sexual Selection I

  1. Sex
    1. What is sex? Why did it evolve?
    2. Disadvantages
      1. Cost of meiosis (cost of making males)
      2. Costs of fractional relatives
      3. Costs of mate finding and mating
      4. Cost of catching a sexually transmitted diseases
    3. Advantages
      1. Viability differences
      2. Lottery hypothesis
      3. Coevolution hypothesis (Red-queen hypothesis)

  2. Sexual selection
    1. Darwin quotes
      1. "Natural selection depends on the success of both sexes, at all ages, in relation to the general conditions of life."
      2. "Sexual selection depends on the success of certain individuals over others of the same sex in relation to the propagation of the species..."
        1. Epigamic selection
        2. Intrasexual selection
    2. Sexual selected traits

  3. Epigamic selection (female choice)
    1. Why do females choose males?
      1. Male reproductive success
      2. Female reproductive success
      3. Because female RS is not affected by additional matings, females should be more choosy than males
    2. Bases of choice
      1. Parental care
      2. Resources
      3. Genes
        1. Runaway selection ("sexy sons") hypothesis
        2. Good genes" hypothesis