A heritable long tail lowers survival but is preferred by mates. Under what condition can sexual selection favour it overall?

• When mate preference raises mating success, with survival left out of the comparison
• When mating benefits exceed survival costs in expected reproductive contribution
• When reduced survival is offset by greater energy invested in growing the tail

In the parental-investment argument, what tendency is predicted when greater investment makes one sex less available for mating?

• More choice by the less-available sex and more competition by the other
• More choice by females and more competition by males, based on gamete size
• More competition by the less-available sex and more choice by the other

Males fight for mating opportunities, and females choose among males. How are these two processes classified?

• Fights: intersexual choice; female choices: intersexual choice
• Fights: intrasexual contests; female choices: intrasexual contests
• Fights: intrasexual contests; female choices: intersexual choice

A male spends hours displaying instead of feeding his chicks. Which opportunity cost is established by this description?

• The chick-feeding effort forgone while he uses those hours to display
• The reduction in chick survival caused by those missed feeds
• The energy spent on chick feeding before those hours

In a fish population, males invest more overall. Brooding delays their next mating, so ready males are scarce relative to females. Which tendency does the investment argument predict?

• Greater male competition for ready females and greater female choosiness
• Greater female competition for ready males and greater male choosiness
• Less female competition and less male choice as brooding limits mating

A study finds greater male investment, fewer ready males, female competition and male choice. What does this role-reversed case show about the investment argument?

• The observations support the prediction under the measured investment and readiness conditions
• The observations establish investment as the explanation for mating roles across species
• The observations challenge the prediction because the competing individuals are females

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

A loud song attracts mates and raises predation risk. A student calls it an honest signal of condition. No relationship between song and condition has been measured. Which conclusion is supported?

• Predation cost establishes honesty because producing the song is risky
• Mate preference establishes honesty because listeners favour the song
• The song's honesty remains untested without evidence linking it to condition