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?

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

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

J. B. S. Haldane once remarked that he'd be willing to lay down his life to save two brothers or eight cousins. Explain what he meant.

Researchers are very interested in studying identical twins who were raised apart. Among other things, they hope to answer questions about the roles of inheritance and upbringing in human behavior. Why do identical twins make such good subjects for this kind of research? What do the results of such studies suggest to you? What are the potential pitfalls of this research? What abuses might occur in the use of these data if the studies are not evaluated critically?

Mass strandings of whales occur on beaches near military exercises where sonar is used, raising concerns about the effects of human-generated underwater sounds on animal behavior. Scientists are collecting behavioral data on several species of whales to find out how sonar affects them.Whales communicate with one another using sound. What is one benefit and one cost to whales of using sound to communicate underwater?

SCIENTIFIC THINKING Jane Goodall's work revealed that in areas of abundant food, chimpanzees may live in groups of several dozen individuals. State a hypothesis about the chimpanzee mating system that could be tested by observing one of these groups. What data would you collect to test your hypothesis? How would you interpret the results? (Note: A sexually mature female chimpanzee undergoes a hormonal cycle about 36 days long that is reflected in easily observed changes in the appearance of her genital area. Females are most sexually receptive, and males are most attracted to them, for about a week during the middle of the cycle.)