Deadly Passion

Deadly Passion

Multiple Choice

Red-crowned cranes breed in spring and early summer. Choose a proximate explanation:

• Breeding is most likely to be successful in spring and early summer.

• Increasing day length triggers the release of breeding hormones.

• Ample food is available for chicks at this time.

Multiple Choice

Red-crowned cranes breed in spring and early summer. Choose an ultimate explanation:

• Breeding is most likely to be successful in spring and early summer.

• Hormonal changes in the spring trigger breeding behaviors.

• Breeding is triggered by the effect of increased day length on the birds’ photoreceptors.

Multiple Choice

If the Mistaken Prey hypothesis is correct, what would you predict?

• Females would sometimes attack males as soon as they enter her web.

• 65% of females would cannibalize their mates.

• Females would only attack males when they somersault to dangle in front of her jaws.

Multiple Choice

If the Mate Rejection hypothesis is correct, what would you predict?

• Females would attack males only during copulation.

• Cannibalized males would be smaller and produce fewer offspring than non-cannibalized males.

• Cannibalized males would father twice as many offspring as non-cannibalized males.

Multiple Choice

If the Hungry Lover hypothesis is correct, what would you predict?

• Females would only eat males that somersault to dangle in front of their jaws.

• Cannibalized males would be smaller and produce fewer offspring than non-cannibalized males.

• Females would be more likely to cannibalize males if their diet has not been supplemented.

Multiple Choice

Choose a proximate explanation for female cannibalism:

• The female eats the male because he dangles his abdomen in front of her jaws.

• The female can produce a larger egg sac if she eats the male.

• The female gains nutrients by eating her mate.

Multiple Choice

Choose an ultimate explanation for female cannibalism:

• The female eats the male because he dangles his abdomen in front of her jaws.

• The female gains nutrients from eating the male.

• The female copulates longer while eating her mate.

Multiple Choice

If the Paternal Investment hypothesis is correct, what would you predict?

• Consuming the male would significantly increase the number and mass of eggs in the female’s egg sac.

• The male’s food value would be low because his mass would be only 1-2% of the mass of the female.

• Eggs in the same egg sac could be fertilized by more than one male.

Multiple Choice

If the Nuptial Gift hypothesis is right, what would you predict?

• Non-cannibalized males would copulate longer than cannibalized males.

• Cannibalized males would father more offspring than non-cannibalized males.

• 65% of females would cannibalize their mates.

Multiple Choice

Choose a proximate explanation for male self-sacrifice:

• The male’s somersault is triggered when he inserts a palp in the female’s sperm receptor.

• The male is providing nutrients to his offspring.

• A male that is cannibalized fathers twice as many offspring.

Multiple Choice

Choose an ultimate explanation for male self-sacrifice:

• The male increases the length of copulation by sacrificing himself.

• The male’s self-sacrifice is an innate, genetically programmed behavior.

• The male is providing nutrients to his hungry mate.