1. Reproductive behavior Bower birds: Males build elaborate structures Females are attracted to these structures Occasionally a female will mate with a male after inspecting his bower After mating the female leaves never to return

2. Reproductive behavior WHY? Bowers are not nests They take an incredible effort to build

3. Reproductive behavior Boys and bowers: build them bigger build them better

4. Do human males create displays to attract females? Does the size of the display relate to relate to: Commitment? Resources? Success? Do human females really go for the elaborate “bower?”

5. Differential reproductive investment patterns copyright © Dennis Kunkel. 1.Potential sexual partners are traders and sex is an exchange Trades must be equitable Value is based on supply and demand 2.Male investment in sperm is far lower than female investment in eggs 3.Male investment in rearing offspring tends to be low 4.Male reproductive potential far higher than female Therefore: The operational sex ratio is male biased Males have surplus supply but high demand

6. Differential reproductive investment equates to different motives/roles/morphs

7. Sexual selection The theory that competition for mates drives the evolution of certain traits. Because operational sex ratio biases exist there can be selective pressure Intrasexual selection: within sex pressure Intersexual selection: between sex pressure Image: from Darwin’s The Descent of Man and selection in relation to sex Tufted Coquette Lophornis ornatus, female on left, ornamented male on right Intersexual selection Intrasexual selection

8. Test of theory: when operational sex ratio is reversed… males with low reproductive rate or with high parental investment …what should happen? Sex role reversals Male pipefish are selective for more color and fertile females

9. Male dominance and mating success Elephant seals: the most dominant males are the most successful Polygamous mating systems tend to produce selective pressure for size Monogamous seals do not exhibit size differences Dimorphisms in Humans?

10. Male alternative sexual strategies: When your not the biggest and the best. …or for that matter if your late to the party Interference Deception Sneak copulations