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Sexual Selection (I)

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Sexual Selection (I) Costs of sex Cost of meiosis Cost of producing males Cost of courtship and mating Benefits of sex Protection against mutations (Muller s ... – PowerPoint PPT presentation

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Title: Sexual Selection (I)


1
Sexual Selection (I)
2
Costs of sex
  • Cost of meiosis
  • Cost of producing males
  • Cost of courtship and mating

3
Benefits of sex
  • Protection against mutations (Mullers ratchet)
  • Protection against environmental changes (Raffle
    hypothesis)
  • Protection against biotic fluctuations (Red Queen
    hypothesis)

4
The Red Queen hypothesis
Now here, you see, it takes all the running
you can do to keep in the same place.
5
Why do male and female gametes differ in size?
  • Geoffrey Parker et al.
  • divergent evolutionary selection
  • favoured two types of gametes
  • small and mobile (sperm)
  • sedentary and packed with nutrients (eggs)

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Darwin (1871, p256) We are, however, here
concerned only with that kind of selection, which
I have called sexual selection. This depends on
the advantage which certain individuals have over
other individuals of the same sex and species, in
exclusive relation to reproduction.
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Sexual selection
  • 1. More individuals are produced than manage to
    reproduce
  • 2. Individuals differ in their ability to compete
    with others for mates or to attract members of
    the opposite sex
  • Result the evolution of traits that enhance
    reproductive success while decreasing survivorship
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