1. A sign stimulus, innate releasing mechanism, fixed action pattern, and supernormal stimuli—
a.are mechanisms associated with behaviors that are learned
b.are components of behaviors that are innate
c.involve behaviors that cannot be explained in terms of ultimate causation
d.involve behaviors that are not subject to natural selection
The correct answer is b—
A. Answer a is incorrect.All of the components listed are associated with behaviors in which learning is conspicuously absent as a mechanism that could alter a behavior when the context of the behavior changes. In the egg-rolling behavior, for example, learning to differentiate between eggs and other objects in the vicinity of nests could reduce energy and time wasted in the retrieval and subsequent removal of inappropriate items (beer cans!)
The correct answer is b—are components of behaviors that are innate
B. Answer b is correct.Each of the terms listed refers to components of behaviors that are notable in the lack of a role of learning and the apparent inflexible control of an innate mechanism (genes).
The correct answer is b—
C. Answer c is incorrect.Even innate traits are subject to evolution. For example, in the egg-rolling behavior, if there was a large cost (fitness) to rolling an inappropriate item into the nest, there would be selection for a change in the sign stimulus, leading to a change in the behavior.
The correct answer is b—
D. Answer d is incorrect.Natural selection could modify any of the components of an innate behavior as long as there is genetic variation, heritability, and a fitness cost/benefit.
2. In operant conditioning—
a.an animals learns that a particular behavior leads to a reward or punishment
b.an animal associates an unconditioned stimulus with a conditioned response
c.learning is unnecessary
d.habituation is required for an appropriate response
The correct answer is a—an animals learns that a particular behavior leads to a reward or punishment
A. Answer a is correct. Operant conditioning involves association between an action by an individual and an unambiguous outcome.
The correct answer is a—
B. Answer b is incorrect.It is not an unrelated stimulus that is linked to a conditioned response; it is a behavior.
The correct answer is a—
C. Answer c is incorrect.Conditioning is a type of learning.
The correct answer is a—
D. Answer d is incorrect.Habituation is a form of nonassociative learning,whereas conditioning (operant or classical) is a form of associative learning.
3. The study of song development in sparrows showed that—
a.the acquisition of a species-specific song is innate
b.there are two components to this behavior―a genetic template and learning
c.song acquisition is an example of associative learning
d.all of the above
The correct answer is b—
A. Answer a is incorrect.Song development in sparrows showed that although there is a genetic component in song development, the young needed to hear the correct song for them to sing the song correctly. Song development is not innate in sparrows but may be in some other species of birds, such as the cuckoos.
The correct answer is b—there are two components to this behavior—a genetic template and learning.
B. Answer b is correct. Song development in sparrows demonstrates the interaction between instinct and learning. Sparrows have a genetic template or instinctive program that guides them to learn their species-specific song but they also have to hear their song in order to learn it correctly. The genetic template alone is insufficient for the sparrow to learn its song.
The correct answer is b—
C. Answer c is incorrect.Song acquisition is a partially learned behavior but not through associative learning. Associative learning involves the association of a stimulus and a response or the association between two stimuli. Song acquisition in sparrows does not involve this type of learning. Song acquisition is learned more through practice.
The correct answer is b—
D. Answer d is incorrect.There is only one correct answer, answer b. Although there is a genetic component of song development in sparrows, there is also a learning component and so it is not completely innate. And although there is a learning component, it is more by practice than by associative learning.
Hint: The work of Peter Marler and his colleagues on the acquisition of courtship song by white-crowned sparrows provides an excellent example of the interaction between instinct and learning in the development of behavior. His experiments suggested that these birds have a genetic template, or instinctive program, that guides them to learn the appropriate song. During a critical period in development, the template will accept the correct song as a model. Thus, song acquisition depends on learning, but only the song of the correct species.
4. The difference between following a set of driving directions given to you by somebody on the street (for example, “… take a right at the next light, go four blocks and turn left…” etc.) and using a map to find your destination is the difference between—
a.navigation and orientation, respectively
b.learning and migration, respectively
c.orientation and navigation, respectively
d.is why birds are not capable of orientation
The correct answer is c—
A. Answer a is incorrect.Using a map is an example of navigation.
The correct answer is c—
B. Answer b is incorrect.Learning and migration are not two alternative behaviors. In animal migration, learning is often involved.
The correct answer is c—orientation and navigation, respectively
C. Answer c is correct. Orientation is the ability to follow a bearing (even if it changes as in a set of directions), and navigation involves an ability to follow bearings and to evaluate one’s geographic position relative to an ultimate destination (for example, based on learning, experience, etc.).
The correct answer is c—
D. Answer d is incorrect.There is good evidence of the many examples of migration that birds can orient and navigate.
5. One of most important differences between signaling in courtship and that in territorial marking is that—
a.the former is always species-specific
b. the latter is always species-specific
c.both always involves a stimulus–response chain
d.the former is always initiated by males
The correct answer is a—the former is always species-specific
A. Answer a is correct. The major function of courtship signals is to help this ensure that individuals mate with members of the same species. Without assurance, mating is likely to be unsuccessful.
The correct answer is a—
B. Answer b is incorrect.Signaling in territoriality can provide information not just to conspecifics, but also to other competing species.
The correct answer is a—
C. Answer c is incorrect.A stimulus–response chain is a very specific form of behavioral signals in which each behavior acts as a releaser for a subsequent behavior, usually leading to the culmination of a specific event (for example, egg laying and fertilization).
The correct answer is a—
D. Answer d is incorrect.In either case, both males and females can initiate communication through signaling. It is not always males.
6. Behavioral ecology assumes—
a.that all behavioral traits are innate
b.learning is the dominant determinate of behavior
c.behavioral traits are subject to natural selection
d.behavioral traits do not affect fitness
The correct answer is c—
A. Answer a is incorrect.Although a behavioral trait, like other traits, must have a genetic basis to evolve, there is a lot of evidence that behavioral traits are a function of learning and genetics.
The correct answer is c—
B. Answer b is incorrect.Learning is a major component of many behaviors, but is not solely responsible for behavioral traits.
The correct answer is c—behavioral traits are subject to Natural Selection
C. Answer c is correct. The study of behavioral ecology is concerned with how traits evolve due to their effects on the fitness of individuals. That is, what behavioral traits are adaptive, and how.
The correct answer is c—
D. Answer d is incorrect.It is clear that some behaviors have positive or negative consequences for the survival reproduction of individuals.
7. According to optimal foraging theory—
a.individuals minimize energy intake per unit of time
b.energy content of a food item is the only determinant of a forager’s food choice
c.time taken to capture a food item the only determinant of a forager’s food choice
d.a higher energy item might be less valuable than a lower energy item if it takes too much time to capture the larger item
The correct answer is d—
A. Answer a is incorrect.According to the optimal foraging theory, animals tend to feed on prey that maximize their net energy intake per unit of foraging time.
The correct answer is d—
B. Answer b is incorrect. According to the optimal foraging theory, energy content has to be considered along with the amount of time required to capture and eat the item. A highly valuable item in terms of energy content might also take a long time to capture or eat.
The correct answer is d—
C. Answer c is incorrect.According to the optimal foraging theory, time is important but only in the context of energy value of the item.
The correct answer is d—higher energy item might be less valuable than a lower energy item if it takes too much time to capture the larger item
D. Answer d is correct.Energy value is divided by time to determine the overall value of the food item. A food item that contains a lot of energy might be harder (take longer) to eat, making items that contain less energy but are easier to eat more valuable.
Hint: Foraging behaviors occur when the net energy gained by feeding is maximized such that the energy content of the prey minus the energy costs of pursuing and handling it. The optimal foraging theory suggests that natural selection favors individuals who tend to feed on prey that maximizes their net energy intake per unit of foraging time/amount of energy.
8. The showy tail feathers of a male peacock evolved because they—
a.improve reproductive success
b.improve male survival
c.reduce survival and reproductive success
d.none of the above
The correct answer is a—improve reproductive success
A. Answer a is correct.The increased eyespots increase the number of mates, leading to an increase in reproductive success.
The correct answer is a—
B. Answer b is incorrect.If anything, the showy tail feathers probably reduce survival by attracting predators or by reducing flying capabilities.
The correct answer is a—
C. Answer c is incorrect. If both survival and reproduction are reduced by a trait, it could not evolve by natural selection.
The correct answer is a—
D. Answer d is incorrect.One of the previous answers is correct.
9. From the perspective of females, extra-pair copulations (epc)—
a.are always disadvantageous
b.always provide indirect benefits such as good genes
c.might be beneficial if the benefit gained from an epc mate outweighs the cost
d.can only occur if the epc male has a “handicap” trait
The correct answer is c—
A. Answer a is incorrect.Epc can be beneficial to a female if her offspring are of higher quality or have access to more resources than if the female mated only with a pair male.
The correct answer is c—
B. Answer b is incorrect.Epc males might also provide care to help raise offspring.
The correct answer is c—might be beneficial if the benefit gained form sharing an epc mate outweighs the cost
C. Answer c is correct.The potential payoff to a female will be determined by considering the advantages and disadvantages of epc. For example, even if an epc male does not help rear offspring, it may contribute superior genes to those offspring, increasing their likelihood of survival or future reproductive success.
The correct answer is c—
D. Answer d is incorrect.A handicap trait (good genes) is not the only way an epc male can improve a female’s fitness.
10. In the haplodiploidy system of sex determination, males are—
a. haploid
b.diploid
c. sterile
d.not present because bees exist as single-sex populations
The correct answer is a—haploid
A. Answer a is correct. In the haplodiploidy system of sex determination, the males are haploid and the females are diploid but sterile (except for the queen). The males fertilize the queen and because the male is haploid, all offspring will inherit all of the father's alleles.
The correct answer is a—
B. Answer b is incorrect.The males are haploid, not diploid. The nonqueen females are diploid but sterile.
The correct answer is a—
C. Answer c is incorrect.The males have to be fertile; it is their "job" to fertilize the queen. They wouldn't be much use to the hive if they were sterile.
The correct answer is a—
D. Answer d is incorrect.Male bees do exist but as in all eusocial systems; they have a single job within the society—to fertilize the queen.
Hint: The origin of eusociality in hymenopterans (that is, bees, wasps, and ants) can be viewed in terms of kin selection. In these insects, males are haploid and females are diploid. This unusual system of sex determination, called haplodiploidy, leads to an unusual situation. If a single male fertilizes the queen, then all female offspring will inherit exactly the same alleles from their father.
11. According to kin selection, saving the life of your ______would do the least for increasing your inclusive fitness.
a. mother
b.brother
c. sister-in-law
d. niece
The correct answer is c—
A. Answer a is incorrect.In saving the life of your mother you save 1/2 of your alleles, which can then be passed on to another offspring. This will increase your inclusive fitness.
The correct answer is c—
B. Answer b is incorrect.In saving the life of your brother you save 1/2 of your alleles, which can then be passed on to another generation of offspring. This will increase your inclusive fitness.
The correct answer is c—sister-in-law
C. Answer c is correct. Because your sister-in-law isn't a "blood" relation, you share no alleles with her. Saving your sister-in-law will do nothing to increase your inclusive fitness.
The correct answer is c—
D. Answer d is incorrect.In saving the life of your niece you save 1/8 to 1/4 of your alleles, which can then be passed onto another generation of offspring. This will increase your inclusive fitness.
Hint: Selection that favors altruism directed toward relatives is called kin selection. Although the behaviors being favored are cooperative, the genes are actually "behaving selfishly," because they encourage the organism to support copies of themselves in other individuals. On average, full siblings will share half of their alleles with each other and will also share half of their alleles with each parent. By contrast, cousins will, on average, only share one-eighth of their alleles.
12. Altruism—
a.is only possible with reciprocity
b.is only possible with kin selection
c.cannot be explained given the way natural selection operates
d.will only occur when the fitness benefit of a given act is greater than the fitness cost
The correct answer is d—
A. Answer a is incorrect.Although reciprocity can make altruistic acts payoff, it is not the only mechanism.
The correct answer is d—
B. Answer b is incorrect. Although kin selection can make altruistic acts payoff, it is not the only mechanism.
The correct answer is d—
C. Answer c is incorrect. Altruism can evolve under natural selection, both through kin selection and reciprocity. There are many examples of altruism in natural populations. Some of the most prominent ones come from studies of social insects, and social vertebrates, in which kin selection and reciprocity can both be important.
The correct answer is d—will only occur when the fitness benefit of a given act is greater than the fitness cost
D. Answer d is correct. Altruistic behaviors must have a benefit for them to evolve. In general, the benefit to an individual must exceed the cost of the behavior. If those conditions hold, natural selection will favor the altruistic act.
Challenge Questions
1. Refer to Figure 54.26.
Data on size of mussels eaten by shore crabs suggests they eat sizes smaller than expected by an optimal foraging model. Suggest a hypothesis for why and describe an experiment to test your hypothesis.
Answer—Presumably, the model is basic, taking into account only size and energetic value of mussels. However, it maybe that larger mussels are in places where shore crabs would be exposed to higher levels of predation or greater physiological stress. Similarly, it could be that the model underestimated time costs or energy returns as a function of mussel size. In the case of large mussels being in a place where shore crabs are exposed to costs not considered by the model, one could test the hypothesis in several ways. First, how are the sizes of mussels distributed in space? If they are completely interspersed that would tend to reject the hypothesis. Alternatively, if the mussels were differentially distributed such that the hypothesis was reasonable, mussels could be experimentally relocated (change their distribution in space) and the diets would be expected to shift to match more closely the situation predicted by the model.
- Refer to Figure 54.27.
Six pairs of birds were removed but only four pairs moved in. Where did the new pairs come from? Additionally, it appears that many of the birds that were not removed expanded their territories and that the new residents ended up with smaller territories than the pairs they replaced. Explain.
Answer—The four new pairs may have been living in surrounding habitat that was of lower quality, or they may have been individuals that could not compete for a limited number of suitable territories for breeding. Often, the best territories are won by the most aggressive or largest or otherwise best competitors, meaning that the new territory holders would likely have been less fierce competitors. If new residents were weaker competitors (due to aggression or body size), then the birds not removed would have been able to expand their territories to acquire even move critical resources.