2. Learning Objectives
• Describe how behavior can improve survival.
• Describe how behavior can improve
reproductive success.
• Describe the benefits and drawbacks of
living in a group.
• Compare and contrast the behavioral
adaptations of solitary and social animals.
• Explain why male cuttlefish mimic females of
the species.
Section 9-4 Opener Now hear this! Two common European toads communicate.
FIGURE 9-17 Maximizing reproductive success in fruit flies.
FIGURE 9-26 Large variance in reproductive success. Studies of the Xavante Indians of Brazil show that the range in number of offspring over their lifetime is much greater for men than for women.
FIGURE 9-20 A costly decision. Because of the investment the male bush cricket is required to make when fertilizing a female, he chooses a mate very carefully.
FIGURE 9-21 Four factors that influence a female's choice of mate.
FIGURE 9-30 Loud and true. The female Natterjack toad is attracted to the biggest male with the loudest call預n "honest signal," because there is no way for a small toad to fake the call volume of a larger toad.
FIGURE 9-22 Preventing paternity uncertainty. A prolonged period of mating prevents the female from accessing other males, assuring the male of reproductive success.
FIGURE 9-23 A reasonable trade-off? The male black widow spider ensures his paternity by an extreme form of mate guarding.
FIGURE 9-27 (part 1) Size says a lot. Species with large males and small females are very likely to be polygamous. Species with similarly sized males and females are likely to be monogamous.
FIGURE 9-24 King of the beach. The biggest, best-fighting male elephant seals control the beach and mate with as many females as possible.
FIGURE 9-27 (part 2) Size says a lot. Species with large males and small females are very likely to be polygamous. Species with similarly sized males and females are likely to be monogamous.
FIGURE 9-25 Let's stay together. Parental investment that is roughly equal often leads to monogamous mating behavior in birds
FIGURE 9-9 Sacrificing her safety for the sake of relatives. At great risk to herself, a female Belding's ground squirrel will make an alarm call in order to save her family members from a predator.
FIGURE 9-11 Reading the will. How likely are you to inherit money from a family member?
FIGURE 9-12 The gift of life. A starving vampire bat receives blood from another, well-fed bat. The recipient of the blood will return the favor one day
FIGURE 9-13 You scratch my back, I'll scratch yours. One vervet monkey will groom another, but expects assistance in return.
FIGURE 9-14 Charitable acts can give us pleasure. In the small hunter-gatherer groups in which humans evolved, altruistic behaviors would be reciprocated. Today, the pleasure we feel in response to such behaviors remains—even though the favor may never be returned.
Start at 15 seconds in…turn on the sound.
FIGURE 9-28 Chemical, auditory, and visual communication. Many animal behaviors require communication: the ability to convey and receive information from other animals.
FIGURE 9-29 Dancing, signing, and speaking. Animals have evolved a variety of ways to convey complex information to others.
