Exploring Mating Systems

1
Exploring Mating Systems

• Jennifer de Puzo
• Kathryn Marshall
• Maribel Pulido

2
Agenda

• Females and Fighting
• Aphrodisiacs and Love Potions
• Finding a Partner for Copulation
• Homosexuality
• Monogamy
• Theories of Monogamy

3
Females of various species fight, just like the
males do.

• Rarely do females fight, and when they do, they
  do not fight to kill each other.
• Females will often resort to various manipulative
  actions.
• Females may also take preventative actions to
  keep her mate.
• Females may use a more passive strategy to keep
  her mate.

4
Females have evolved to fight over males for
certain reasons

• Desperation - when there are very few males
• Aspiration - choosing to mate with superior males
• Possessiveness - keeping her mate from taking a
  mistress

5
Aphrodisiacs and Love Potions

• Male Sneaky Strategies    
• Male decreasing females sex drive  
• Antiaphrodisiac
• Aphrodisiac
• Seminal Fluids
• Some alter female behavior
• Can be beneficial in some species

6
Aphrodisiacs and Love Potions

• Females are fighting against the males sneaky
  strategies
• Less susceptible to monogamy with hometown
  species
• Two experiments where females are fighting back

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Finding a Partner for Copulation

• It is difficult for females to find males to
  fertilize eggs
• Rapidly evolving protein
• New species emerging
• Effects of a repeated evolving protein
• Mutations
• Advantages of mutations

8
Homosexuality

• Three Conditions for homosexuality
• Genetic
• Homosexual behavior is exclusive
• Incidents of homosexual behavior
• Heterozygote advantage
• Fertile humans
• Genetic homosexuality

9
Monogamy

• Monogamy will evolve as a strategy for all
  members of a population only when it is in the
  best interest of both males and females
• Monogamy will last when the amount of surviving
  children of monogamous couples exceeds those of
  polygamous couples

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Theories of Monogamy

• Good Wife Theory of Monogamy
• Males opportunities to philander are lessened
• Females obsessively faithful so mate can help
  raise offspring
• Unlikely to apply for three reasons
• sexual fidelity can be in the males interest
• monogamy can occur even if male does not help
  raise children
• females need for male help does not guarantee
  her fidelity

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Theories of Monogamy

• Danger Theory of Monogamy
• males might find that they are better off staying
  with a single female and keeping rivals away
• might be risky to leave because finding another
  female would involve a dangerous or long journey
• Pop-Em-Out Theory of Monogamy
• deals with the time between a females breeding
• if the female breeds quickly, then there may be
  no point for a male to leave on a journey to find
  another female

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Theories of Monogamy

• Sociopath Theory of Monogamy
• Monogamous organisms often aggressive toward
  others
• Usually thought that aggression due to monogamy
• If aggressive individuals have more surviving
  offspring than more amiable creatures, then
  monogamy may arise as a side effect of that
  aggression
• Mutually Assured Destruction Theory of Monogamy
  (MAD)
• Cheating or desertion by either partner results
  in total reproductive failure for both

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Physical Characteristics Related to Monogamy

• In monogamous species, males and females tend to
  be roughly the same size
• Human males tend to be slightly larger than
  females
• Testicle size usually associated with the risk of
  sperm competition
• Small testicles - low risk of sperm competition
  (gorillas)
• Medium-sized testicles -low to moderate risk of
  sperm competition (humans)
• Enormous testicles - high risk of sperm
  competition (chimpanzees)

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Post-Presentation Discussion

• Thank you for your time!