Chapter 12: Family, Society, and Evolution
Topic: the social environment Difficulty: moderate
1. Part of the research by Sinervo and Lively on side-blotched lizard (Uta stansburiana) dealt with
proportions of males of the orange, blue, and yellow morphs in a population of this species.
What did they find?
A) Individuals of the large, aggressive orange morph were always most numerous.
B) Individuals of the smaller blue morph were always most numerous.
C) Individuals of the female-mimic yellow morph were always most numerous.
D) There was a predictable cycling in frequencies of the three morphs.
Answer: D
Topic: dominance hierarchy Difficulty: moderate
2. The spatial organization of flocks or herds may be related to social rank of individuals. How
does this principle apply to flocks of wood pigeons?
A) Dominant individuals tend to be at the periphery of the flock, where they can serve as
lookouts.
B) Dominant individuals tend to be at the center of the flock, where they can feed relatively
undisturbed.
C) Dominant individuals tend to spread themselves evenly throughout the flock, so as to avoid
confrontations with other dominant individuals.
Answer: B
Topic: social contests Difficulty: moderate
3. When two spiders meet to contest a potential web site, which of the following will predispose the
two individuals to fight?
A) high quality web site
D) dissimilar sizes of the spiders
B) similar sizes of the spiders
E) both A and B
C) low quality web site
F) both C and D
Answer: E
Topic: social contests Difficulty: easy
4. Game theory:
A) is primarily aimed toward understanding of outcomes that depend on probabilities of
different events.
B) is primarily aimed toward understanding outcomes that depend on the behaviors of players.
C) is useful in the study of human gambling habits, but has little applicability in ecology.
Answer: B
Topic: social groups Difficulty: easy
5. Which of the following comes closest to constituting a true social group?
A) flies attracted to a dung pat
B) cattle attracted to a desert watering hole
C) goldfinches flocking to feed together on seed heads of plants growing in open fields
D) aggregation of the progeny of an oak tree because of their failure to disperse
Answer: C
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Chapter 12: Family, Society, and Evolution
Topic: costs and benefits of social behaviors Difficulty: easy
6. A crow attacks a red-tailed hawk flying nearby. Which of these two birds is the donor of the
attacking behavior?
A) the crow B) the red-tailed hawk
Answer: A
Topic: costs and benefits of social behaviors Difficulty: moderate
7. A blue jay attempts to displace a cardinal from a small bird feeder. The cardinal stands its
ground and the blue jay backs off. Which bird is the recipient of the second behavior?
A) the blue jay B) the cardinal
Answer: A
Topic: costs and benefits of social behaviors Difficulty: easy
8. Two lionesses kill an old gazelle. Just as they begin to eat the gazelle, they are chased away by a
male lion, who then proceeds to eat his fill. Which of the following behaviors is illustrated in
this example?
A) cooperative B) altruistic C) selfish D) spiteful
Answer: C
Topic: costs and benefits of social behaviors Difficulty: easy
9. A man runs into his burning home to rescue his young son. Which of the following behaviors is
illustrated in this example?
A) cooperative B) altruistic C) selfish D) spiteful
Answer: B
Topic: costs and benefits of social behaviors Difficulty: moderate
10. A firewoman runs into a burning home to rescue a small child to whom she is unrelated. Which
of the following behaviors is illustrated in this example?
A) cooperative B) altruistic C) selfish D) spiteful
Answer: B
Topic: social groups Difficulty: easy
11. Birds feeding in a flock benefit because, as the flock size increases, each bird spends less time
looking out for predators. Is there any disadvantage to the individuals as flock size increases?
A) No, the larger the flock the better.
B) Yes, larger flocks depress local food supplies more quickly, forcing more frequent moves
between foraging patches.
Answer: B
Topic: kin selection Difficulty: moderate
12. What is the coefficient of relationship (probability of identity by descent) of a human individual
to one of its grandparents?
A) 1.0 B) 0.75 C) 0.5 D) 0.25 E) 0.125
Answer: D
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Chapter 12: Family, Society, and Evolution
Topic: kin selection Difficulty: moderate
13. When an individual is the donor of a specific behavior toward another individual, the inclusive
fitness of that behavior for the donor is dependent on the coefficient of relationship between the
donor and the recipient.
A) true B) false
Answer: A
Topic: kin selection Difficulty: hard
14. If C is the cost of a particular behavior for the donor, B is the benefit of the behavior to the
recipient, and r is the coefficient of relationship, what does the equation C < Br describe?
A) conditions under which a selfish behavior will increase in the population
B) conditions under which a selfish behavior will decrease in the population
C) conditions under which an altruistic behavior will increase in the population
D) conditions under which an altruistic behavior will decrease in the population
Answer: C
Topic: costs and benefits of social behaviors Difficulty: moderate
15. The meerkat (Suricata suricatta), a social mongoose of southern Africa, has been studied
carefully to determine whether or not its guarding behavior is altruistic. Guarding behavior in
this species does not appear to incur a cost to the individuals performing it. Is this behavior
altruistic?
A) Yes, because the behavior benefits kin of the individuals performing the behavior.
B) No, because altruistic behaviors must incur a cost to the individuals performing them.
Answer: B
Topic: cooperative behavior among unrelated... Difficulty: moderate
16. Interactions among unrelated individuals are governed by self-interest. Selfish behaviors in a
social setting pose a paradox, however. What is this paradox?
A) Reproductive success of selfish individuals may be greater than that of cooperative
individuals.
B) Reproductive success of selfish individuals may be less than that of cooperative individuals.
C) Reproductive success of selfish individuals may be the same as that of cooperative
individuals.
Answer: B
Topic: cooperative behavior among unrelated... Difficulty: moderate
17. When a social organization consists of cooperative individuals, selection will always favor
individuals that increase their personal reproductive success by __________.
A) becoming more cooperative
C) performing spiteful behaviors
B) performing altruistic behaviors
D) cheating
Answer: D
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Chapter 12: Family, Society, and Evolution
Topic: cooperative behavior among unrelated... Difficulty: moderate
18. In the hawk-dove game, the hawk:
A) always behaves selfishly in conflict situations.
B) always behaves cooperatively in conflict situations.
C) always wins in conflict situations.
D) always receives the same payoff, regardless of the behavior of its opponent.
Answer: A
Topic: cooperative behavior among unrelated... Difficulty: moderate
19. In the hawk-dove game, the dove:
A) always behaves selfishly in conflict situations.
B) always behaves cooperatively in conflict situations.
C) always wins in conflict situations.
D) always receives the same payoff, regardless of the behavior of its opponent.
Answer: B
Topic: cooperative behavior among unrelated... Difficulty: moderate
20. In the hawk-dove game, a world of hawks:
A) cannot be invaded by the dove strategy.
B) is difficult to invade by the dove strategy.
C) is easily invaded by the dove strategy.
Answer: B
Topic: cooperative behavior among unrelated... Difficulty: moderate
21. In the hawk-dove game, a world of doves:
A) cannot be invaded by the hawk strategy.
B) is difficult to invade by the hawk strategy.
C) is easily invaded by the hawk strategy.
Answer: C
Topic: cooperative behavior among unrelated... Difficulty: hard
22. What must be true for doves to invade a world of hawks successfully?
A) The potential reward or benefit must be less than twice the cost of conflict.
B) The potential reward or benefit must be more than twice the cost of conflict.
C) The potential reward or benefit must be equal to the cost of conflict.
Answer: A
Topic: parent-offspring conflict Difficulty: easy
23. The interests of parents and their offspring are generally compatible. However, parent-offspring
conflicts arise when:
A) accumulation of resources by one offspring increases the overall fecundity of its parents.
B) accumulation of resources by one offspring has no effect upon the overall fecundity of its
parents.
C) accumulation of resources by one offspring reduces the overall fecundity of its parents.
Answer: C
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Chapter 12: Family, Society, and Evolution
Topic: parent-offspring conflict Difficulty: moderate
24. From a parent's perspective, all offspring are equivalent, having a coefficient of relationship of
0.5 to the parent. Parents should thus compare the benefit (B) of providing additional care to an
offspring to the cost (C) of forgoing some future reproductive success. When the benefit:cost
(B:C) ratio falls below one of the following values a parent will cease providing care to an
offspring in favor of producing a new one. Which value is it?
A) 2.0 B) 1.0 C) 0.5 D) none of the above
Answer: B
Topic: parent-offspring conflict Difficulty: hard
25. From an offspring's perspective, its siblings are not as valuable as itself, because its siblings have
a coefficient of relationship of 0.5 (compared to its own coefficient of 1.0). Offspring should
thus compare the benefit (B) of accepting additional care from their parents to the cost (C) this
care represents for future reproductive success (production of more siblings) of their parents.
When the benefit:cost (B:C) ratio falls below one of the following values an offspring will cease
to accept additional care from its parents. Which value is it?
A) 2.0 B) 1.0 C) 0.5 D) none of the above
Answer: C
Topic: eusociality Difficulty: easy
26. Examples of eusociality may be found among which of the following animal groups?
A) termites (Isoptera)
D) both A and B
B) ants, bees, and wasps (Hymenoptera)
E) A, B, and C
C) mammals
Answer: E
Topic: eusociality Difficulty: easy
27. The worker caste in bees consists entirely of:
A) reproductive males in an arrested stage of development.
B) reproductive females in an arrested stage of development.
C) reproductive males.
D) reproductive females.
Answer: B
Topic: eusociality Difficulty: moderate
28. In the Hymenoptera, there is a strong asymmetry in the genetic relatedness of siblings. Of
particular interest is the coefficient of relationship of a female worker to her siblings,
__________.
A) 1.0 B) 0.75 C) 0.5 D) 0.25 E) 0.125
Answer: B
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Chapter 12: Family, Society, and Evolution
Topic: eusociality Difficulty: moderate
29. Female workers in the Hymenoptera forego their own reproduction and instead lavish care on
their siblings, which are predominantly sisters. Why is this?
A) Caring for siblings requires less energy than caring for their own broods.
B) Caring for siblings requires less time than caring for their own broods.
C) Workers achieve higher inclusive fitness by caring for siblings than they would by caring for
their own broods.
D) There is no evolutionary explanation for this behavior.
Answer: C
Topic: family, society, and evolution Difficulty: easy
30. Interactions among members of the same species delicately balance cooperation and competition,
altruism and selfishness.
A) true B) false
Answer: A
Use the following to answer questions 31-35:
You are a senior biology major in your last semester at State University. Next year you plan to attend
graduate school in your specialty area, social behaviors of animals. At mid-semester the State
University Biology Club hosts its semi-annual mixer for all biology majors. You're enjoying this large
and boisterous party when you meet one of your friends, an underclassperson. Your friend is currently
taking an introductory ecology course and is quite excited about recently presented material on social
behaviors. A small group of students has gathered around your friend to discuss this topic, and you join
in the debate. You quickly determine that your friend's understanding of social behaviors is somewhat
flawed, and you feel obliged to intervene occasionally to set the record straight.
Topic: costs and benefits of social behaviors Difficulty: moderate
31. You sense immediately that your friend is confused about the difference between cooperative
and altruistic behaviors, using the two terms interchangeably. How do you clarify the difference
between these behaviors for the group?
Answer: Behaviors have donors and recipients. Cooperative and altruistic behaviors are similar
in that both result in benefit to their recipients. However, these two behaviors differ
considerably in their effects on donors. Cooperative behaviors benefit donors, whereas altruistic
behaviors are performed at a cost to donors.
Topic: costs and benefits of social behaviors Difficulty: moderate
32. Your friend also appears to be confused about the difference between selfish and spiteful
behaviors, using these terms interchangeably. Once again you feel compelled to intervene,
clarifying the difference between these behaviors for the group. What do you tell them?
Answer: Selfish and spiteful behaviors are similar in that both result in costs to their recipients.
However, these two behaviors differ considerably in their effects on donors. Selfish behaviors
benefit donors, whereas spiteful behaviors are performed at a cost to donors.
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Chapter 12: Family, Society, and Evolution
Topic: costs and benefits of social behaviors Difficulty: moderate
33. Your friend claims to have seen several examples of spiteful behaviors performed by various
nonhuman animals. You are quite skeptical of this claim, given your understanding of the
evolutionary basis for behaviors. Why are you skeptical and what kind of behavior do you
suspect your friend has actually observed?
Answer: Behaviors have a genetic basis and are subject to natural selection. For alleles
governing a particular behavior to increase in a population, the behavior must increase the fitness
of its donors. Because spiteful behaviors, by definition, do not benefit either their donors or their
recipients, there appears to be no circumstance under which they would be favored by natural
selection. Quite probably your friend has been observing selfish behaviors, which benefit their
donors at a cost to their recipients.
Topic: costs and benefits of social behaviors Difficulty: moderate
34. The conversation moves to the topic of altruistic behaviors. Your friend is of the opinion that
truly altruistic behaviors cannot exist because they are performed at a cost to their donors. You
ask your friend if the ecology course has covered kin selection yet. When you discover that the
course has not yet covered this topic, you propose to the group that altruism can evolve under
certain circumstances. What do you propose (in a general, non-mathematical way)?
Answer: You propose that altruistic behaviors can arise when they are performed among close
relatives. The fundamental idea is that such behaviors increase the inclusive fitness of their
donors because alleles shared by donors and recipients increase in frequency when the fitness of
donors is increased. In other words, altruistic behaviors can evolve by way of kin selection.
Topic: costs and benefits of social behaviors Difficulty: moderate
35. Your friend talks excitedly about cooperative behaviors, which benefit both donors and
recipients. Several others in the group begin to argue that cooperative behaviors should evolve
commonly among unrelated individuals in large populations because of the mutual benefits
involved. Indeed, several members of the discussion group suggest that cooperative behaviors
should increase in populations to the complete exclusion of selfish behaviors. You are less
optimistic about this possibility. In a general, non-mathematical way, how do you explain your
reservations to the group?
Answer: Cooperative strategies are indeed the best all around from a social perspective.
However, a population structured solely by cooperative behaviors is evolutionarily unstable
because it is readily invaded by genotypes exhibiting selfish behaviors. In a population of
cooperators, an individual who behaves selfishly derives great personal benefit, which translates
into increased fitness for selfish genotypes compared to cooperative ones. Selfish genotypes will
thus rapidly expand in populations comprised primarily of cooperative genotypes.
Topic: territoriality Difficulty: easy
36. A __________ is any area defended by an individual against intrusion by others.
Answer: territory
Topic: dominance hierarchy Difficulty: easy
37. A __________ is sometimes also referred to as a "pecking order."
Answer: dominance hierarchy
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Chapter 12: Family, Society, and Evolution
Topic: costs and benefits of social behaviors Difficulty: easy
38. When a behavior is directed toward another individual, that individual is referred to as the
__________ of the behavior.
Answer: recipient
Topic: costs and benefits of social behaviors Difficulty: easy
39. In typical sexually reproducing species, an individual's highest coefficient of relationship (aside
from that with itself) is with its __________.
Answer: siblings
Topic: costs and benefits of social behaviors Difficulty: easy
40. The total fitness of a gene responsible for a particular behavior is referred to as its __________
fitness.
Answer: inclusive
Topic: cooperative behavior among unrelated... Difficulty: moderate
41. Despite human wishes to the contrary, a world of cooperative individuals ("doves") cannot resist
evolutionary invasion by selfish ("hawkish") behavior. Thus we say that dove behavior is not an
evolutionarily __________ strategy.
Answer: stable
Topic: parent-offspring conflict Difficulty: easy
42. Continuing parental care of offspring presents benefits and costs to both parents and offspring.
As offspring mature and become more self-sufficient, the benefit:cost ratio (B:C) declines. The
period of maturation between B:C values of 1.0 and 0.5 represents a period of __________.
Answer: parent-offspring conflict
Topic: eusociality Difficulty: easy
43. The highest "grade" of sociality in the animal world is referred to as __________.
Answer: eusociality
Topic: eusociality Difficulty: easy
44. In eusocial species, an individual or group of individuals that performs a specific task (queen,
worker, etc.) is said to belong to a specific __________.
Answer: caste
Topic: eusociality Difficulty: easy
45. In the Hymenoptera, males develop from unfertilized eggs and appear in colonies only as
reproductive __________ that leave the colony to seek mates.
Answer: drones
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Chapter 12: Family, Society, and Evolution
Topic: kin selection Difficulty: hard
46. You and your sister are each married and each of you have two children. You have both decided
that the number of children you ultimately have will be governed by your respective abilities to
send these children to college. You have investments that will be worth $300,000 when your
two children are ready to go to college. You reckon that a college education will cost $100,000
per child. You are contemplating having a third child when your sister approaches you with a
proposition. She also has two children and has investments that will be worth $200,000 when
her children are ready to go to college. She'd like to have three children. She asks if you'll
forego having a third child and give her the extra $100,000 so she can have a third child and send
him or her to college. From an evolutionary perspective, do you find this altruistic venture to be
attractive?
Answer: From an evolutionary perspective, the cost (C) to the donor of an altruistic act relative
to its benefit (B) to the recipient must be less than the coefficient of relationship (r) of the donor
and recipient. Your coefficient of relationship to your sister (assuming she's not an identical
twin) is 0.5. In this simplistic scenario, you would be giving up one offspring to enable your
sister to have one offspring. The ratio of C/B is thus 1.0, which exceeds the coefficient of
relationship. Thus from an evolutionary perspective you would decline this offer as an
unattractive one. In general, you should only be willing to forego having an additional offspring
if your altruistic act enables your sibling to produce more than two additional offspring.
Topic: kin selection Difficulty: moderate
47. How does kin selection constrain the evolution of selfish behaviors among close relatives?
Please answer this question with explicit consideration of costs, benefits, and genetic relatedness.
Answer: The theory of kin selection considers the cost (C) of a selfish behavior to its recipient
relative to the benefit (B) of that behavior to its donor. For a selfish behavior to evolve, the cost,
benefit, and coefficient of relationship (r) must conform to the relationship B > Cr. In other
words, the benefit to the donor must exceed the cost to the recipient discounted by the coefficient
of relationship. Among close relatives, where r is high, selfish behaviors will only evolve when
their cost:benefit ratio is relatively small.
Topic: kin selection Difficulty: hard
48. One might presume that a cooperative behavior among unrelated individuals would evolve only
when the benefit of the act to the donor exceeds the cost of the same behavior to the donor. In
natural populations, we sometimes observe cooperative behaviors in which the donor's cost
appears to exceed the donor's benefit. For example, the cost (increased predation risk) to an
individual of serving as a group's sentinel might outweigh the benefit to the individual (reduced
predation risk) when others serve as sentinels. What might be an evolutionary explanation for
the persistence of such behaviors?
Answer: It is likely that such behaviors have an altruistic component. There is some degree of
genetic relatedness among the individuals within any population, especially if the population is
small and to some extent inbred. Donors can tolerate some excess of personal costs relative to
personal benefits, if benefits also accrue to recipients who are relatives.
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Chapter 12: Family, Society, and Evolution
Topic: kin selection Difficulty: moderate
49. Studies of white-fronted bee-eaters in Africa have revealed that behaviors among individuals
belonging to extended families are structured by the degree of relatedness of these individuals.
In other words, close relatives are treated better than distant relatives. What very important
ability does this finding suggest?
Answer: Bee-eaters must be capable of determining and discriminating among different degrees
of genetic relatedness.
Topic: kin selection Difficulty: hard
50. Male peacocks often perform their elaborate mating displays in groups. Recent research has
shown that large group displays are more attractive to females than displays performed by
individuals or small groups. However, when a female is attracted to a group of males, only the
dominant male of the group mates with her. This raises an interesting question: how do nonmating males benefit by contributing their displays (presumably at some cost) to a group in
which they cannot mate?
Answer: These males would have little chance of mating if they left the group and attempted to
display individually to females. Yet there must be some benefit to displaying in groups. There
are several possibilities. First, the males in a group may be closely related, suggesting the
operation of kin selection. Indeed, studies have shown that males displaying in groups are often
brothers. Another possibility is that the death of the dominant male in a group would create an
immediate mating opportunity for another male in the group. Such benefits must outweigh the
costs of foregoing reproduction, at least temporarily.
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