Hamilton's rule states that an altruistic allele could spread in a population if Br>C, where B represents the fitness benefit to the recipient, r is the coefficient of relatedness between altruist and recipient, and C represents the fitness cost to the altruist. If r=0.5 between the altruist and the recipient, what would the ratio of costs to benefits have to be for the altruistic allele to spread?a. C/B>0.5b. C/B>0c. C/B<0.5d. C/B < 0

The male cuttlefish in the chapter-opening photo can rapidly change their skin colors (under nerve control) to flash warning patterns to rivals. Predict the proximate and ultimate causes of this behavior.

In Module 35.3, you learned that Norway rat offspring whose mothers don't interact much with them grow up to be fearful and anxious in new situations. Suggest a possible ultimate cause for this link between maternal behavior and stress response of offspring. (Hint: Under what circumstances might high reactivity to stress be more adaptive than being relaxed?)

Propose an evolutionary hypothesis to explain the observation that some bird populations do not migrate if people supply food for them in feeders.

A chorus of frogs fills the air on a spring evening. The frog calls are courtship signals. What are the functions of courtship behaviors? How might a behavioral ecologist explain the proximate cause of this behavior? The ultimate cause?

Crows break the shells of certain molluscs before eating them by dropping them onto rocks. Hypothesizing that crows drop the molluscs from a height that gives the most food for the least effort (optimal foraging), a researcher dropped shells from different heights and counted the drops it took to break them. a. The researcher measured the average drop height for crows and found that it was 5.23 m. Does this support the researcher's hypothesis? Explain. b. Describe an experiment to determine whether dropping molluscs from an optimal height is learned or innate.

Evolutionary biologist Hopi Hoekstra and colleagues have hypothesized that the burrow-digging behavior of mice (and the resulting shape of their underground burrows) is heritable—innate and not learned. Design an experiment to test this hypothesis.

The tendency of individuals to choose mates who are like themselves is called .a. natural selection;b. sexual selection;c. assortative mating;d. the founder effect;e. random mating

Scientists studying scrub jays found that it is common for 'helpers' to assist mated pairs of birds in raising their young. The helpers lack territories and mates of their own. Instead, they help the territory owners gather food for their offspring. Propose a hypothesis to explain what advantage there might be for the helpers to engage in this behavior instead of seeking their own territories and mates. How would you test your hypothesis? If your hypothesis is correct, what kind of results would you expect your tests to yield?