Q&A Hero

Q: How could infanticide be seen as a male reproductive strategy? Why is infanticide more prevalent in species that form one-male, multifemale groups than in multimale, multifemale groups? Is there evidence that this is an adaptive strategy? Explain your answer.

Q: Explain the relationship between body, canine, and testis size and the following forms of social organization: (a) pair-bonded groups; (b) one-male, multifemale groups; and (c) multimale, multifemale groups.

Q: Define sexual selection, and compare/contrast its two main forms: intersexual selection and intrasexual selection.

Q: How can dominance status affect female reproductive success? Illustrate your answer with specific primate examples.

Q: As an evolutionary biologist, how would you explain the relationship between animal behavior and strategy, cost, and benefit to a layperson? Make sure to define what you mean by "strategy."

Q: If infanticide is a reproductive strategy for males, then a. males should kill all the infants already in the group when they take over. b. males should kill all the infants already in the group, regardless of where the mothers are in their cycle. c. infanticide should be associated with group size and composition. d. infanticide should be correlated with a change in male residence or status in the group.

Q: Male primates commit infanticide in one-male, multifemale groups because a. it enhances male attractiveness to females. b. females without nursing infants resume sexual receptivity. c. females do not want infants sired by a nonalpha male. d. they want to limit the number of males in their group.

Q: Dominance hierarchies are seen in multimale, multifemale groups because hierarchies a. give low-ranking males a chance to compete. b. let females know which males to mate with. c. mediate male"male competition. d. prevent infanticide.

Q: Through genetic testing and behavioral research, researchers have shown that a. low-ranking males mate guarded more often and sired more offspring. b. high-ranking males sired more offspring than low-ranking males. c. low-ranking males were outcompeted during female cycles and did not sire any offspring. d. high-ranking males mate guarded females but only during cycles when they did not conceive.

Q: In gelada baboon social units, "follower" males a. reproduce more successfully, independent of rank. b. are found in groups with small numbers of females. c. do not increase the tenure of "leader" males. d. sire approximately 17% of offspring in the group.

Q: Direct male"male competition is most intense ina. pair-bonded groups. b. one-male, multifemale groups. c. multimale, multifemale groups.d. bachelor groups.

Q: Males can reduce the cost of dispersal by a. dispersing with peers or joining all-male groups. b. dispersing alone but staying close to their original groups. c. dispersing at night close to other groups. d. dispersing far from their natal group.

Q: Recent studies indicate that high-ranking male primates have a. lower reproductive success than low-ranking or alien males. b. higher reproductive success than low-ranking or alien males. c. reproductive success equal to that of low-ranking and alien males. d. limited reproductive success because of the stress of high rank.

Q: When male primates disperse, they often move to groups that are nearby because a. those groups usually have the best females to mate with. b. male primates prefer not to travel long distances alone. c. the cost of dispersal is high due to predation risk and poor access to resources. d. they know the neighboring groups, so they do not have to compete as fiercely for access.

Q: In social groups in which there is mate guarding, a. females groom males more frequently. b. males have little parental investment. c. extrapair copulations result in a percentage of offspring. d. genetic testing has shown it is effective against extrapair copulation.

Q: Large body sizes that require more energy and weaponry that can cause severe injury demonstrate that a. sexual selection is stronger than natural selection. b. natural selection is stronger than sexual selection. c. male reproductive success varies less than female reproductive success. d. intersexual selection is strong in primates.

Q: Which type of social group has the largest relative testis size?a. Pair bonded b. One-male, multifemale c. Multimale, multifemaled. One female, multimale

Q: Which type of social group has the most sexual dimorphism in canine size?a. Pair bonded b. One-male, multifemale c. Multimale, multifemaled. One female, multimale

Q: Which of the following is true of primates in general? a. Pair-bonded groups have the least amount of sexual dimorphism in body size. b. One-male, multifemale groups have less dimorphism in body size than do pair-bonded species. c. Multimale, multifemale groups are not dimorphic in body size. d. Multimale, multifemale groups tend to have greater sexual dimorphism than one-male, multifemale groups.

Q: Which of the following characteristics would you expect to find in a species in which there is extreme competition among males for access to females?a. Drab pelage b. Equal body size c. Small canine teethd. Specialized weaponry

Q: Intrasexual selection favors traits that a. enhance direct competition among individuals of the same sex. b. are attractive to the opposite sex. c. increase survival. d. are easily adapted to change.

Q: Intersexual selection a. favors traits that enhance direct competition among individuals. b. favors traits that are attractive to the opposite sex. c. is a direct result of the environment. d. produces variation in survival between the sexes.

Q: Sexual selection a. favors phenotypes that help survival. b. produces the same characteristics in both sexes. c. enhances offspring survival. d. favors traits that increase the ability to compete for mates.

Q: Male reproduction is limited by a. the number of sex cells a male produces. b. parental investment and infant care. c. the number of fertile females. d. food availability.

Q: The single factor that can compensate for low rank and its corresponding decrease in reproductive success isa. age at maturity. b. choice of mates. c. positive social relationships.d. longevity.

Q: Female nonhuman primates often begin to reproduce before they are fully grown. Empirical evidence supports the idea that these young females a. can achieve high fertility and low infant mortality equivalent to middle-age and older females. b. will have shorter interbirth intervals than fully grown females. c. will have lower fertility than middle-age females. d. will not achieve full adult size in their lifetime.

Q: Primate mothers modify their investment in their offspring a. when offspring can give alarm calls. b. with the mother's need to conserve resources. c. after they conceive the next offspring. d. depending on their mating system.

Q: Primate researchers have found a positive correlation between female dominance rank anda. number of births per year. b. length of interbirth interval. c. infant mortality.d. rank of associates.

Q: The reproductive success of primate females depends upona. interbirth interval variation. b. group composition and size. c. predation pressure.d. the number and quality of offspring.

Q: Which of the following statements is true of a group with a female dominance hierarchy? a. Low-ranking howler females stay in their natal groups when dispersal is difficult. b. There is no survival difference between the offspring of high- and low-ranking female long-tailed macaques. c. When subordinate marmoset or tamarin females breed, their infants may be killed by dominant females that have infants of their own. d. high-ranking females maintain low levels of body fat.

Q: Dominance hierarchies occur among females whena. females are unrelated. b. groups are small. c. food is particularly abundant.d. food is clumped and defensible.

Q: Many primate females form dominance hierarchies because a. they compete with one another over access to mates. b. societies run more smoothly with dominance hierarchies. c. some females do not need as many resources as others. d. they compete with one another over access to food.

Q: When compared with low-ranking females, high-ranking females may a. obtain larger quantities of food. b. spend less energy to reproduce. c. travel farther to feed. d. spend more energy in courtship rituals.

Q: If animal A outranks animals B and C, and B outranks C, then the dominance relationships are a. unlikely to produce sexual selection. b. unstable. c. transitive. d. explained by intersexual competition.

Q: Which of the following statements is true? a. Dominance rank is not a good predictor of female reproductive success. b. Young females tend to reproduce more often than older females because they are in better physical condition. c. Variation in longevity is a major contributor to variation in lifetime fitness among females. d. Females in multimale groups have more offspring than females in one-male units.

Q: Which of the following statements about female primate reproductive success is NOT supported by the evidence? a. The longer a female lives, the more offspring she will likely have. b. Past a certain age, female primates stop reproducing, so it does not matter how long they live. c. Younger females have less success with raising offspring because the female is not fully grown and continues to demand energy for her own survival that might otherwise be invested in offspring. d. Among primates, humans are unusual in that females stop reproducing abruptly when they get older and have a potentially long postreproductive period.

Q: Female fertility is greatest ina. young females. b. middle-age females. c. older females.d. primiparous females.

Q: Primiparous females a. reproduce at faster rates than multiparous females. b. give birth to only one infant in their lifetime. c. experience greater infant mortality than multiparous females. d. have shorter interbirth intervals than multiparous females.

Q: For most primates reproductive success of a primate female depends largely on a. group size and composition. b. her ability to acquire nutritive resources. c. her ability to coerce males into investing in offspring. d. male protection.

Q: The reproductive success of primate females is constrained mainly by a. the energetic costs of pregnancy and lactation. b. the availability of males. c. a female's genetic makeup. d. a female's ability to attract mates.

Q: Primates have longer gestation periods than other mammals relative to body size because a. they produce smaller offspring relative to body size than other mammals. b. they have larger brains, relative to body size, than other mammals. c. they have access to more nutritive resources than other mammals. d. they do not possess the morphology for external gestation.

Q: Primate females always invest in their young because a. primate males do not have the appropriate neurological foundation. b. they are committed to parental investment by their physiology. c. they produce large, nutrient-rich gametes. d. parenting effort is equal to mating effort.

Q: Unequal parental investment is favored when a. resource competition is high for females. b. the cost of acquiring additional mates is low for males. c. the cost of acquiring additional mates is high for males. d. the fitness of offspring raised by two parents is much higher than the fitness of offspring raised by one parent.

Q: Because primates are mammals, what can you predict about their reproductive strategy? a. Resource competition forces pair-bonding. b. Alpha males sire almost all of the offspring. c. Males assist in rearing offspring in most cases. d. Females are obligated to invest heavily in their offspring through pregnancy and lactation.

Q: Which of the following best describes a particular primate mating system and reproductive behavior? a. In baboons females compete with other females for mating opportunities with prime males, whereas males rarely compete with each other. b. Male preference can influence female reproductive success in groups where there are multiple males. c. In most pair-bonded species, both males and females care for offspring. d. In polyandrous species, both males and females have equal opportunities to mate.

Q: The relative amount of parental care a. can affect all aspects of social behavior and some aspects of morphology. b. is virtually the same across the primate order. c. does not influence reproductive strategies. d. is determined directly by dominance hierarchy.

Q: The majority of primate species are not pair-bonded. Therefore, we can predict that a. both sexes will care for offspring equally. b. neither sex will care for offspring. c. males will provide more care for offspring than will females. d. females will provide more care for offspring than will males.

Q: Because behavioral strategies are thought to be the product of natural selection, they should increasea. reproductive success. b. the cost-to-benefit ratio. c. adaptations.d. trade-offs.

Q: In the language of adaptive explanations, cost and benefit refer to the impact of behaviors on the animal'sa. overall health. b. reproductive success. c. foraging success.d. social relationships.

Q: In the language of adaptive explanations, what is meant by the term "strategy"? a. A mechanism that leads to particular behaviors in particular contexts b. A conscious decision to make adaptive behavioral choices c. A conscious decision to make adaptive or nonadaptive behavioral choices d. A behavior of higher animals, such as mammals

Q: Which of the following statements is true?a. Patterns of courtship, mate choice, and parental care vary greatly within the primate order.b. The reproductive strategies of living primates are not influenced by their phylogenetic heritage as mammals.c. Studies of primate reproductive behavior cannot help us understand how evolutionary forces shaped the reproductive strategies of our hominin ancestors.d. The same factors limit male and female reproductive success.

Q: Which of the following plays a crucial role in our understanding of primate societies?a. Metabolism b. Diet c. Mating systemsd. Physiology

Q: To better understand primate societies, we need to investigate the way primates find mates and care for their offspring. This is known as theira. social organization. b. social system. c. mating system.d. reproductive strategy.

Q: Discuss the main factors contributing to the endangerment and extinction of primates.

Q: Using the information from the chapter on how ecology shapes behavior, create a model showing how certain ecological pressures might have favored sociality in primates.

Q: What adaptations do some plants have to make themselves less palatable to animals that might otherwise eat them? Explain the primate counteradaptations that allow them to eat such plants.

Q: How do active metabolism, growth rate, and reproductive effort affect basal metabolism?

Q: Imagine you discover a new species of primate. It has a large body size (about 35 lbs.), is sexually dimorphic, appears to spend much of its time in the trees, lives in dense tropical forest, and has longer arms than legs. Based on this information only, what can you hypothesize about this new species' behavior and ecology?

Q: Explain the taxonomic problems associated with members of Tarsiiformes. How would an evolutionary taxonomist classify these organisms within the order Primate? How would a cladist classify these organisms within the primates?

Q: Compare and contrast five differences in morphology and behavior between the strepsirrhine primates and the haplorrhine primates. Make a distinction between ancestral and derived traits in your discussion.

Q: Compare and contrast how primates differ from other mammals in each of the following categories and give a specific example for each one: (a) limbs and locomotion, (b) teeth and diet, (c) the senses, (d) the brain and intelligence, and (e) behavior.

Q: Summarize the changes in manual dexterity and sensory reorganization that accompanied the evolution of primates.

Q: Explain how reasoning from homology and reasoning from analogy can help us to understand our own species better.

Q: How is the comparative method used in the study of primate behavior and ecology? Explain how it might help researchers understand the evolution of behavior and morphology.

Q: The United States has a. increased the number of imported primates in recent decades. b. decreased the number of imported primates in recent decades. c. not changed the number of imported primates in recent decades. d. allows only the importation of certain primates.

Q: Which of the following contributes to the endangerment of primates?a. Infanticide b. Subsistence foraging c. Biomedical researchd. Small-scale agricultural projects

Q: Which of the following contributes to the endangerment of primates? a. Habitat destruction b. Infanticide c. Selective foresting d. Resource competition with conspecifics

Q: A typical day in the life of a primate a. changes significantly day to day. b. is consumed by socializing with group members. c. is unaffected by seasonal changes in environment. d. includes two long feeding bouts, once in the morning and once in the late afternoon.

Q: The size and composition of primate social groups are a compromise between a. competition for mates and competition for food. b. body size and home range size. c. costs and benefits of sociality. d. competition for food and benefits of sociality.

Q: If primates make different calls when they detect other species nearby, then one could predict a. they want to attract the other species so they can find them. b. they want to define their territory. c. those calls are to defend their resources. d. those are specific alarm calls to avoid predation.

Q: Cercopithecines a. typically live in small one-male groups. b. typically live in groups where all the females are related. c. typically live in groups where all the males are related. d. are typically monogamous.

Q: Sociality is costly to primates because a. there is greater competition for resources. b. there is increased vulnerability to disease. c. there is increased vulnerability to attacks from conspecifics. d. they have to share home ranges with other primates.

Q: Most primate species a. live in social groups. b. live solitary lives. c. live in social groups only during the breeding season. d. are only social when predator activity is high.

Q: Which of the following statements is true? a. Estimated predation rates vary from less than 1% to 15% of the population per year in primate populations. b. Estimated predation rates per month are from 1% to 15% in primate populations. c. Adults are 10% more susceptible to predation than are subadults. d. Arboreal species are more susceptible to predation than are terrestrial species.

Q: Evidence that predation is important in primates includes a. its frequent observance. b. the observation that many primate species have antipredator defenses. c. the fact that predators are in the same areas as primates. d. primates are an easy prey species because of their size.

Q: In primates, territoriality occurs when a. females defend food or males defend access to females. b. females defend access to males or males defend food. c. males defend access to both food and females. d. females defend access to both food and males.

Q: Resource-defense territoriality occurs when a. resources are distributed over a wide area. b. resources are abundant and thus worth defending. c. food is clumped in a space. d. females are clumped in space.

Q: You are given a jawbone of an unknown primate, and you notice that the anterior and posterior cusps of the lower molars form two parallel ridges. What might you conclude from this observation? a. This is the mandible of a frugivore. b. This is the mandible of a folivore. c. This is the mandible of a cercopithecine. d. This is the mandible of an ape.

Q: Modern primates are found in the tropical and temperate zones ofa. Madagascar, Africa, and Australia. b. Africa, Asia, Europe, and Antarctica. c. Africa, Asia, and the New World.d. China, Japan, and Australia.

Q: Territories are a. fixed areas defended by members of a group against conspecifics. b. fixed areas defended by members of a group against other species. c. areas where members of a group are often found. d. areas where groups come together in areas where their ranges overlap.