Deck 6: Primate Mating Systems

Question 1

Birds and mammals have very different typical reproductive strategies. What is a key reason for this?

A) In birds, both males and females can provide a great deal of parental investment for the young, because both can incubate the egg(s) and both can bring food to the chick(s).
B) Birds are not as highly evolved as primates, so they have simple undifferentiated mating systems mostly involving male songs and calls.
C) With their larger brains, mammals can form a wider range of relationships than can birds and therefore can form more productive mating systems.
D) Because they can fly, birds do not experience limitations on food availability and therefore undergo mainly sexual selection and almost no natural selection.

Answer 1

A

Question 2

What is estrous?

A) the period of most intensive competition among females for access to potential male mates
B) the sum of male and female parental investment
C) the period of time during which a female is receptive to mating
D) the length of time between births, or the "interbirth interval"

Answer 2

C

Question 3

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.

Answer 3

B

Question 4

Which of the following is true of the relative amount of parental care typical for a given species?

A) It can affect all aspects of social behavior and some aspects of morphology.
B) It is virtually the same across the primate order.
C) It does not influence reproductive strategies.
D) Dominance hierarchy directly determines it.

Question 5

Because behavioral strategies are thought to be the product of natural selection, they should increase

A) genetic fitness.
B) the cost-to-benefit ratio.
C) adaptations.
D) trade-offs.

Question 6

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.

Question 7

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.

Question 8

Variance in reproductive success is a key driving factor in evolution. How does this affect sexual selection in mammals?

A) Male variance can be much greater than female variance, so males are potentially under very strong sexual selection.
B) Female variance can be much greater than female variance, so females are potentially under very strong sexual selection.
C) The level of variance determines the amount of resources shunted into parental investment; the sex with the highest variance produces the most food for offspring.
D) The sex with the lowest variance, usually mammals, has the highest average number of offspring.

Question 9

Which of the following plays a crucial role in our understanding of primate societies?

A) metabolism
B) diet
C) mating systems
D) physiology

Question 10

Primates have longer gestation periods than other mammals relative to body size because they

A) produce smaller offspring, relative to body size, than other mammals.
B) have larger brains, relative to body size, than other mammals.
C) have access to more nutritive resources than other mammals.
D) do not possess the morphology for external gestation.

Question 11

To better understand primate societies, we need to investigate the way primates find mates and care for their offspring. This is known as their

A) social organization.
B) social system.
C) mating system.
D) reproductive strategy.

Question 12

How are most birds different from most mammals in their reproductive strategies?

A) Most birds are pair-bonded, while most mammals are not.
B) Most mammals are pair-bonded, while most birds are not.
C) Birds tend to reproduce randomly from season to season, while mammals form longer-term bonds.
D) Most birds produce a single offspring each time they reproduce, while mammals tend to produce one offspring at a time.

Question 13

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.

Question 14

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.

Question 15

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.

Question 16

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

Question 17

In primates, females usually provide far more parental investment than males. Why?

A) Primates are mammals, and in mammals, females lactate and males do not.
B) Primate males have other responsibilities, including defending territories, so females must always provide most parental investment.
C) Primates require a great deal of parental investment, and females are genetically better at providing parental investment.
D) Sexual selection is unable to operate on female mammals.

Question 18

In evolutionary biology, cost and benefit refer to the impact of behaviors on the animal's

A) overall health.
B) genetic fitness.
C) foraging success.
D) social relationships.

Question 19

In primate species that are not pair-bonded, 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.

Question 20

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.

Question 21

Which of the following statements is true of sexual selection?

A) It favors phenotypes that help survival.
B) It produces the same characteristics in both sexes.
C) It enhances offspring survival.
D) It favors traits that increase the ability to compete for mates.

Question 22

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) well-camouflaged or dull-colored coat
B) female body size larger than male body size
C) larger canine teeth in females than in males
D) larger canine teeth in males than in females

Question 23

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.

Question 24

Dominance hierarchies occur among females when

A) females are unrelated.
B) groups are small.
C) food is particularly abundant.
D) food is clumped and defensible.

Question 25

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.

Question 26

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 lifetimes.

Question 27

Which of the following statements is true of intersexual selection?

A) It favors traits that enhance direct competition among individuals.
B) It favors traits that are attractive to the opposite sex.
C) It is a direct result of the environment.
D) It produces variation in survival between the sexes.

Question 28

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 become pregnant, their infants may be killed by dominant females that have infants of their own.
D) high-ranking females maintain low levels of body fat.

Question 29

High-ranking female baboons have much higher food intake than low-ranking female baboons. How can a female baboon compensate for her low rank and acquire more food?

A) forage at the center of the group where she can spend less time avoiding predators and more time eating
B) provide the dominant females with a portion of her food so they will allow her to eat in peace
C) forage on the periphery of the group, but with a cost: she will be more vulnerable to predators
D) living longer

Question 30

When females can defeat all the females ranked below them and none of the females ranked above them, dominance relationships are said to be

A) unlikely to produce sexual selection.
B) unstable.
C) transitive.
D) explained by intersexual competition.

Question 31

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.

Question 32

Primate researchers have found a positive correlation between female dominance rank and

A) number of births per year.
B) length of interbirth interval.
C) infant mortality.
D) rank of associates.

Question 33

The reproductive success of primate females depends upon

A) interbirth interval variation.
B) group composition and size.
C) predation pressure.
D) the number and quality of offspring.

Question 34

Female fertility is greatest in

A) young females.
B) middle-age females.
C) older females.
D) primiparous females.

Question 35

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.

Question 36

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.

Question 37

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.

Question 38

Which type of social group has the most sexual dimorphism in canine size?

A) pair bonded
B) one-male, multifemale
C) multimale, multifemale
D) one female, multimale

Question 39

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.

Question 40

Which of the following is true of primiparous females in primates?

A) They reproduce at faster rates than multiparous females.
B) They give birth to only one infant in their lifetimes.
C) They experience greater infant mortality than multiparous females.
D) They have shorter interbirth intervals than multiparous females.

Question 41

How does the threat of infanticide influence male-female relationships in baboons? Include in your answer a discussion of mating effort and parenting effort.

Question 42

Males can reduce the cost of dispersal by dispersing

A) with peers or joining all-male groups.
B) alone but staying close to their original groups.
C) at night close to other groups.
D) far from their natal groups.

Question 43

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.

Question 44

Which type of social group has the largest relative testis size?

A) pair bonded
B) one-male, multifemale
C) multimale, multifemale
D) one female, multimale

Question 45

When male primates disperse, they often move to groups that are nearby because

A) those groups usually have the best females with which to mate.
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.

Question 46

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.

Question 47

What is the evidence demonstrating the importance of socializing for female primates?

Question 48

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.

Question 49

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

Question 50

In gelada baboon social units, which of the following statements is true of "follower" males?

A) They reproduce more successfully, independent of rank.
B) They are found in groups with small numbers of females.
C) They do not increase the tenure of "leader" males.
D) They sire approximately 17% of offspring in the group.

Question 51

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.

Question 52

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.

Question 53

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

Question 54

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.

Question 55

Discuss the better documented counterstrategies to infanticide evolved by female primates, and give specific primate examples from the reading.

Question 56

Direct male-male competition is most intense in ________ groups.

A) pair-bonded
B) one-male, multifemale
C) multimale, multifemale
D) bachelor

Question 57

Through genetic testing and behavioral research, researchers have shown that

A) low-ranking males mate guarded females 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.

Question 58

Why has Sarah Hardy's infanticide hypothesis been so controversial?

A) Infanticide has never been controversial.
B) There have been no cases of infanticide among primates observed in the wild, though some have been observed in the lab.
C) The hypothesis uses the observation of infanticide among lions to infer that it happens among primates, with no additional proof.
D) At first, the phenomenon was only rarely observed; some thought that since infanticide occurred in nature, this would justify it among humans.

Question 59

In social groups in which there is mate guarding, which of the following is true?

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.

Question 60

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.

Question 61

Explain why it is important that we study and understand reproductive strategies of animals, and primates specifically.