Deck 7: The Evolution of Cooperation

Question 1

Kin selection predicts that

A) altruism is more likely among nonrelatives.
B) altruism is more likely among relatives.
C) altruism should occur only in higher animals.
D) only 50% of related individuals are altruistic.

Answer 1

B

Question 2

Imagine that an alarm caller sacrifices its life to save other conspecifics. According to Hamilton's rule, how many full siblings would it have to save for the behavior to be favored, and why?

A) exactly one, to replace its own genes in the gene pool
B) two, because this equals its own genes plus additional genes to make it worth it
C) three or more, because Hamilton's rule is an inequality
D) exactly three, to replace its own genes in the gene pool most efficiently

Answer 2

C

Question 3

The key to the evolution of altruism is that

A) recipients must be more likely to carry the altruistic allele than nonrecipients.
B) actors must be more likely to carry the altruistic allele than nonactors.
C) recipients must be unrelated to the actors.
D) nonrecipients must be more likely to carry the altruistic allele than recipients.

Answer 3

A

Question 4

Imagine a primate species where a female caregiver often helps raise another female's offspring in a way that reduces her fitness by 10% and increases the fitness of the recipient by 25%. According to Hamilton's rule, in which of the following scenarios could this behavior evolve?

A) in groups where all the siblings are full siblings
B) in groups where all the siblings are half siblings
C) in groups where there are explicit language-based kin terms, such as sister and mother
D) in groups where females always leave before reproducing

Question 5

The coefficient of relatedness (r) between full siblings in primates is

A) 0.25.
B) 0.5.
C) 0.75.
D) 1.00.

Question 6

When group selection and individual selection are opposed, which of the following occurs?

A) Group selection prevails if groups are large and there is little migration.
B) Individual selection prevails.
C) Group selection usually prevails because the conditions for individual selection are too stringent.
D) Group selection never prevails.

Question 7

Which of the following statements correctly describes the coefficient of relatedness (r)?

A) It measures the maximum degree of relatedness between the actor and the recipients.
B) It measures the average degree of relatedness between the actor and the recipients.
C) It indicates the probability that two randomly chosen individuals share the same genetic trait.
D) It is a measure of likelihood that two individuals are members of the same species.

Question 8

The coefficient of relatedness (r) between mother and son in primates is

A) 0.25.
B) 0.5.
C) 0.75.
D) 1.00.

Question 9

By definition, which of the following is true of altruistic behaviors?

A) They incur a cost to the recipient.
B) They incur a cost to the actor.
C) They result in a benefit to the actor.
D) They are beneficial to the recipient and the actor.

Question 10

Which of the following is true of group selection?

A) It is likely to occur in primates because they live in well-established social groups.
B) It is likely to occur in primates because certain behaviors benefit the whole group.
C) It is unlikely to occur in primates because certain behaviors may benefit the group to the detriment of the actor.
D) It is unlikely to occur in primates because they lack sufficient levels of group interaction for a group-oriented behavior to evolve.

Question 11

Altruistic behavior is

A) more likely among kin than among nonkin.
B) more likely among nonkin than among kin.
C) equally likely among kin or nonkin.
D) rare between parent and offspring but common between siblings.

Question 12

The coefficient of relatedness (r) is a measure of

A) each individual's fitness benefits.
B) the probability that two individuals acquire the same allele through descent from a common ancestor.
C) the probability that two randomly chosen individuals share the same genetic trait.
D) parental investment.

Question 13

Which of the following statements about coalitions among male baboons is correct?

A) They allow middle-ranking, cooperative males a chance to gain access to receptive females.
B) They are an example of mutualistic behavior, as all males get equal mating opportunities.
C) They do not allow lower-ranking males to outcompete higher-ranking males.
D) They can predict male grooming relationships.

Question 14

Imagine a primate caregiver who helps raise a conspecific's offspring. Such caregiving reduces her fitness by 50% and increases the fitness of the conspecific by 50%. According to Hamilton's rule, is there a type of group in which this behavior will be favored by kin selection?

A) Yes, this behavior will be favored by kin selection in groups where all of the siblings are full siblings.
B) Yes, this behavior will be favored by kin selection in groups where all the siblings are half siblings.
C) No, this behavior is not likely to evolve in any group unless there are explicit kinship systems available, such as in humans.
D) No, there are no group structures of primates that would favor this behavior.

Question 15

Hamilton's rule states that

A) altruism evolves only among nonkin.
B) selfish genes swamp altruistic genes.
C) altruistic behavior is favored if the cost to the actor is less than the benefit to the recipient, devalued by the degree of relatedness.
D) altruistic behavior is favored if the benefits to the actor are greater than the costs to the recipients, devalued by their degree of relatedness.

Question 16

Altruism at first was a puzzle to evolutionary biologists because it should

A) be more common in nature because it increases the fitness of recipients.
B) be more common in nature because it increases the fitness of species.
C) not be common in nature because it decreases the fitness of actors.
D) not be common in nature because it decreases the fitness of species.

Question 17

Which of the following is true of mutualistic behaviors?

A) They are common in nature when animals work together.
B) They are rare because "slacking" is often profitable for individuals, not groups.
C) They involve only kin and never unrelated individuals.
D) They are profitable for the actor but not the recipient.

Question 18

Two unrelated male baboons work together to guard a female in estrus to keep away a more dominant male. This is an example of

A) mutualism.
B) altruism.
C) reciprocal altruism.
D) kin selection.

Question 19

Although alarm calling benefits the whole group, it cannot be explained by group selection because

A) callers make themselves conspicuous to the predators, but calling costs little in terms of individual fitness.
B) calling reduces the risk of mortality for everyone who hears the call, changing the frequency of callers and noncallers in the population, because everyone benefits.
C) noncallers benefit from the alarm call and will have higher fitness than the callers, so selection will suppress alarm calling.
D) callers and noncallers have the same relative fitness.

Question 20

Which of the following is true of altruism?

A) Altruism is a strategy favored by sexual selection.
B) Altruism can evolve only if the benefit to the group is very high compared with the cost to the actor.
C) Altruism cannot simultaneously increase the fitness of all members of the group.
D) Altruism cannot evolve unless there is no cost to the actor.

Question 21

The apparent stability in female dominance relationships in female-bonded primates may be due to

A) abundant food supply.
B) kin selection.
C) sexual selection.
D) habitat seasonality.

Question 22

Which of the following describes maternal rank and matrilineages in macaque, vervet, and baboon groups?

A) Maternal rank is transferred to offspring, particularly daughters.
B) Maternal kin occupy dissimilar ranks in the dominance hierarchy.
C) Ranking within matrilineages is usually laterally transferred.
D) Female dominance relationships are unstable over time.

Question 23

Studies of kin recognition by female rhesus monkeys suggest that

A) females had weak affinities for their maternal half sisters.
B) facial resemblance could be a cue females use to distinguish paternal half sisters.
C) females preferred agemates to maternal and paternal half sisters.
D) females preferred maternal half sisters to unrelated agemates.

Question 24

Parent-offspring conflict occurs

A) because parents and offspring share all of their genes.
B) because siblings are more closely related to each other than individuals are to themselves.
C) only when siblings are not full siblings.
D) during weaning.

Question 25

The cooperative breeding system of primates such as marmosets and tamarins can be explained by

A) chimerism, which increases fraternal twins' inclusive fitness when they help raise one another's offspring.
B) helpers who care for the offspring of the breeding pair, although the helpers are usually not related to them.
C) the fact that mothers sometimes allow their daughters to breed.
D) mutualism between the nonbreeding helpers.

Question 26

When monkeys recognize paternal kin, they may rely on

A) gender.
B) genotype.
C) age similarity.
D) phenotype.

Question 27

Studies of red howler monkeys have shown that coalitions of

A) fathers and daughters form enduring bonds that are the basis for social groups.
B) related males are more likely to experience rank reversals.
C) unrelated males last four times as long as coalitions of unrelated males.
D) fathers and their maturing sons are necessary to repel incursions into their group by alien males.

Question 28

Which of the following is predicted by Hamilton's rule?

A) r = 0
B) r > 0.0
C) r < 0.0
D) r is greater than the degree of relatedness

Question 29

Recent studies on kin recognition have found that age may provide a good proxy measure of paternal kinship in

A) monogamous species.
B) species where one male dominates mating activity in a group.
C) groups with polygynous mating strategies.
D) polyandrous groups.

Question 30

Which of the following is true of phenotypic matching?

A) It is context dependent.
B) It is common among apes but not monkeys.
C) It is the ability to recognize kin by a feature such as their smell.
D) It favors maternal kin over paternal kin.

Question 31

Which of the following is usually more common among kin than among nonkin in primate groups?

A) aggression
B) foraging
C) alarm calling
D) coalition formation

Question 32

Monkeys and apes recognize their kin through

A) genotype mapping.
B) patterns of male and female associations.
C) contact with their mothers.
D) age estimation of adult males in the group.

Question 33

Which of the following is true regarding parent-offspring conflict?

A) Weaning is an example of parent-offspring conflict because offspring can rely on the fact that they are more closely related to each other than they are to their mother.
B) A mother is equally related to each of her offspring; in contrast, an offspring is at most 25% related to its siblings but is 100% related to itself.
C) A mother is motivated to wean her current infant so she can begin investment in her next infant, but the infant will resist its mother's attempts at weaning because it is not in its genetic best interest.
D) Parent-offspring conflict only occurs in primates because reproductive costs are higher than for other mammals.

Question 34

Monkey A lives in a group with full siblings. Monkey B lives in a group with half siblings. Monkey C lives in a group with cousins. And monkey D lives in a group with its grandparents. For which monkey in which group is altruistic behavior most likely to occur?

A) A
B) B
C) C
D) D

Question 35

Which of the following statements do studies of macaques, vervets, and baboons support?

A) Maternal rank is not a good predictor of a daughter's rank.
B) All members of one maternal kin group rank above or below all members of other matrilineages.
C) The stability of female dominance relationships is not a result of kin-based alliances.
D) Females inherit paternal rank.

Question 36

Which of the following is true of baboon females?

A) They have strong affinities for both maternal and paternal half sisters.
B) They are not able to distinguish maternal and paternal half sisters from unrelated females.
C) They prefer maternal half sisters over paternal half sisters.
D) They prefer paternal half sisters over maternal half sisters.

Question 37

Of the following, which is the most certain way to identify kin in primates?

A) phenotypic matching based on cues that expose underlying genetic similarity
B) similarity in age, suggesting that individuals are litter mates
C) proximity and context that signal possible parent-offspring relationships
D) reconciliation, indicating some sort of closeness between individuals

Question 38

Which of the following does primate altruism include?

A) grooming conspecifics
B) sibling rivalry
C) autogrooming
D) sharing home ranges

Question 39

In primates, which of the following is predicted to occur after conflict results in violence as a way to mend relationships?

A) huddling
B) reconciliation
C) coalition formation
D) altruism

Question 40

Kin selection combined with females remaining in their natal group, in many primate species, has led to

A) mutualistic behavior.
B) asymmetrical behavior.
C) the transmission of rank laterally from sister to sister.
D) the transmission of rank from mothers to offspring.

Question 41

What is group selection? Why do evolutionary biologists believe that individual selection will be more powerful than group selection when the two are in conflict?

Question 42

Matrilines are an example of

A) altruism.
B) a kin recognition mechanism.
C) grooming relationships.
D) dominance relationships.

Question 43

Compare altruism and mutualism in terms of the fitness effects on actors and recipients.

Question 44

In a study done with vervets, researchers found that

A) genetic relatedness is necessary for contingent reciprocity to occur.
B) they ignore recruitment calls from other monkeys after receiving grooming bouts from them.
C) contingent reciprocity can evolve as confederates react appropriately to the presence and absence of reciprocity.
D) agemates were more likely to be reciprocal.

Question 45

What is altruism? Why was it a puzzle for evolutionary biology before Hamilton?

Question 46

In promiscuously mating primate species that live in multimale, multifemale groups, mothers share 50% of their genes with their offspring. In most of these species, different offspring of the same female are likely to share what percentage of their genes with each other?

A) 0%
B) 25%
C) 50%
D) 100%

Question 47

What is Hamilton's rule and how does it work? Provide an example in which a pattern of behavior is explained by reference to Hamilton's rule.

Question 48

Conflict and aggression are a large part of group life for many primate species, which would seem disruptive to social bonds. What, then, keeps social groups cohesive?

Question 49

Reciprocal altruism requires

A) many interactions between kin.
B) the ability to count.
C) that there are no slackers or cheaters.
D) sufficient memory to keep track of altruistic and nonaltruistic acts.

Question 50

In recent studies of chimpanzees, researchers found that

A) possessors of food were less likely to share their food with individuals who had recently groomed them.
B) grooming is not reciprocal.
C) grooming is sometimes a precursor for food sharing.
D) grooming is exchanged for mating opportunities.

Question 51

What evidence exists for reciprocal altruism in primates? Why would reciprocal altruism be common for primates but not for other animals?

Question 52

Reconciliatory contact between opponents immediately following an aggressive encounter can reduce rates of self-scratching, an indicator of stress. If no reconciliation is attempted, then we can assume that

A) rates of self-scratching drop back to baseline, regardless of stress level.
B) rates of self-scratching remain above baseline, indicating high stress levels.
C) only one opponent experiences high stress levels.
D) the opponents will have high rates of aggression between them in the future.

Question 53

Construct a hypothetical example to illustrate how a gene causing altruism in an individual could increase in frequency through kin selection.

Question 54

Even primate "friends" sometimes come into conflict. Their aggressive interactions may not have a detrimental effect on social cohesion if there is

A) kin selection.
B) altruism.
C) grooming.
D) reconciliation.

Question 55

What is the evidence for maternal and paternal kin recognition in primates? Illustrate your answer with examples.

Question 56

Explain the phenomenon of genetic chimeras and how it relates to kin selection in cooperatively breeding marmoset groups.

Question 57

Which of the following statements describes the evidence for reciprocal altruism?

A) It is absent among primates because they cannot recognize kin.
B) It is absent among primates because they do not have long-term memories.
C) It exists among primates because they often live in stable social groups.
D) It exists among primates because of their diverse diet.