A long tail slightly raises predation risk, yet it spreads. How?

• Predators admire long tails and leave their owners alone
• Choosy mates reward it so strongly that mating gains outweigh the survival cost
• Tails grow back overnight, so the risk is imaginary

Which sex competes and which chooses, and why?

• The lower investing sex competes while the higher investing sex chooses
• The larger sex always competes while the smaller always chooses
• Both sexes always compete equally, whatever they invest

Males fight each other while females pick winners. Which is which?

• Both are mate choice, since females are present
• Both are contests, since fighting is involved
• The fights are contests within one sex, and the picking is selection by the other sex

A male spends hours displaying instead of feeding his chicks. What did the display cost him?

• The future broods and fed chicks that time and energy could have bought
• Nothing, since displaying uses no energy at all
• Only his popularity, which never affects offspring

In a fish where males carry the eggs, which pattern do you expect?

• Males display as usual, since maleness fixes the roles
• Females display and compete, while choosy males select
• Neither sex shows any mating behavior at all

A student says role reversed species refute the investment rule. What is the flaw?

• They confirm it, since the higher investing sex chooses in them too
• They are too rare to count as evidence either way
• They prove that only maleness ever matters

Sexual selection acts only through survival, never through mating success.

Circle one:   True   False

A loud song slightly raises predation risk yet spreads fast through a population. What must be true?

• The mating gain from the song outweighs its survival cost
• Predators in that forest have all gone deaf
• Singing costs nothing and risks nothing