Biology 242: Lecture 15Spring 2001

Sex and Sexual Selection

  1. Sex
    1. What is sex? Why did it evolve? Why is it important?
    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 = viability differences from new genotypes
      1. Lottery hypothesis
      2. Coevolution hypothesis (Red-queen hypothesis)

  2. Sexual selection
    1. Darwin quotes
      1. Sexual selection depends on the success of certain individuals over others of the same sex in relation to the propagation of the species..."
      2. "Natural selection depends on the success of both sexes, at all ages, in relation to the general conditions of life."
    2. An important difference between males and females
      1. Female reproductive success
      2. Male reproductive success
    3. Female choice
      1. Why do females choose males?
      2. On what bases do females choose?
        1. Parental care
        2. Resources
        3. Genes
    4. Male-male competition
      1. Why do males compete?
      2. Types of male-male competition
        1. Resource defense polygyny
        2. Female defense polygyny
        3. Lek polygyny
        4. Scramble competition polygyny
      3. Results of male-male competition


"In great attempts it is glorious even to fail."
Wings of Silver