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 female’s 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

7. 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

10. 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 male’s interest • monogamy can occur even if male does not help raise children • female’s need for male help does not guarantee her fidelity

11. 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 female’s breeding • if the female breeds quickly, then there may be no point for a male to leave on a journey to find another female

12. 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

13. 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)

14. Post-Presentation Discussion Thank you for your time!