Deck 7: The Evolution of Cooperation

Question 1

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.

Answer 1

C

Question 2

Coalitions among male baboons

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

Answer 2

A

Question 3

Imagine a 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, in which of the following scenarios could this behavior evolve?

A) Groups of full siblings
B) Groups of half siblings
C) Both types of groups
D) Neither type of group

Answer 3

D

Question 4

When group selection and individual selection are opposed,

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 5

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?

A) at least 1.
B) at least 2.
C) at least 3.
D) Hamilton's rule cannot be satisfied.

Question 6

The key to the evolution of altruism is that

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

Question 7

Group selection

A) is likely to occur in primates because they live in well-established social groups.
B) is likely to occur in primates because certain behaviors benefit the whole group.
C) is unlikely to occur in primates because certain behaviors may benefit the group to the detriment of the actor.
D) is unlikely to occur in primates because it is a theoretically unsound principle.

Question 8

By definition, altruistic behaviors

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

Question 9

Imagine a caregiver who helps raise a conspecific's offspring. Such caregiving 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) Groups of full siblings
B) Groups of half siblings
C) Both types of groups
D) Neither type of group

Question 10

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 11

Mutualistic behaviors

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

Question 12

Altruistic behavior is more likely

A) among kin than among nonkin.
B) among nonkin than among kin.
C) among kin than among nonkin, but only when kin and nonkin have the opportunity to interact.
D) among nonkin than among kin, but only when nonkin interact with each other more than kin do.

Question 13

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 14

Altruism at first was a puzzle to evolutionary biologists because

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

Question 15

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

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

Question 16

Kin selection predicts

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

Question 17

If the coefficient of relatedness between two individuals is zero (r = 0), then

A) altruism can evolve if c > b.
B) altruism can evolve if c < b.
C) altruism cannot evolve via kin selection.
D) altruism will sometimes evolve regardless of the values of c and b.

Question 18

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 an allele.
D) sibling relatedness.

Question 19

The coefficient of relatedness (r) between full siblings is

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

Question 20

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 21

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

A) No altruism should evolve when r < 0.5.
B) Altruism evolves only when r > 0.0.
C) Altruism evolves only when r < 0.0.
D) No altruism should evolve when r > 0.5.

Question 22

When monkeys recognize paternal kin, they may rely on

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

Question 23

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 24

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 25

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 26

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 27

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 28

Phenotypic matching

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

Question 29

Parent-offspring conflict occurs

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

Question 30

Baboon females

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

Question 31

Primate altruism includes

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

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

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 34

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 35

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 36

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 37

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 38

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

A) Weaning is an example of parent-offspring conflict, and this transition reflects a fundamental symmetry in the genetic interests of mothers and offspring.
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 39

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) Matrilineages 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 patrilineal rank.

Question 40

If the coefficient of relatedness between two individuals is 0.5, then

A) altruism can evolve if c > 2b.
B) altruism can evolve if c < 2b.
C) altruism cannot evolve via kin selection.
D) altruism will sometimes evolve regardless of the values of c and

Question 41

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

A) Phenotypic matching
B) Age/cohort
C) Proximity/context
D) Reconciliation

Question 42

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

Question 43

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

Question 44

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

Question 45

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 46

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 47

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

Question 48

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

Question 49

Matrilines are an example of

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

Question 50

Interpret the following inequality as it pertains to parent-offspring conflict. Apply Hamilton's rule, from the current infant's perspective, assuming a gene expressed by the current infant increases maternal investment by a small amount.
1.0 * (increase in fitness of current fetus)
0.5 * (decrease in fitness of future offspring)

Question 51

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 52

In a study done with vervets, researchers found that

A) genetic relatedness is necessary for contingent reciprocity to occur.
B) they responded to 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 53

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

Question 54

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 55

What is Hamilton's rule? What are the two fundamental predictions of Hamilton's rule? Devise a primate scenario in which these two predictions of Hamilton's rule would be satisfied.

Question 56

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 opponent will have high rates of aggression between them in the future.

Question 57

In most promiscuously mating primate species that live in multimale, multifemale groups, mothers share 50% of their genes with their offspring. 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 58

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 59

Evidence for reciprocal altruism

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