1. Behavioral Adaptations to the Environment
Chapter 35
Behavioral Adaptations to the Environment

2. Introduction
Mating is one of the most fundamental activities in the animal world.
Many animals (peacocks, for example) expend considerable time and energy trying to attract a mate.
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3. It’s not easy being beautiful! Figure 35.0_2
Figure 35.0_2 The flamboyant tail feathers of the peacock (Pavo cristatus) 3

4. THE SCIENTIFIC STUDY OF BEHAVIOR
THE SCIENTIFIC STUDY OF BEHAVIOR
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5. 35.1 Behavioral ecologists ask both proximate and ultimate questions
Behavior encompasses a wide range of activities.
A behavior is an action (carried out by muscles or glands) under the control of the nervous system in response to an environmental cue.
Collectively, behavior is the sum of an animal’s responses to internal and external environmental cues.
Behavioral ecology is the study of behavior in an evolutionary context.
Student Misconceptions and Concerns
Students may misunderstand inherited factors and the environment as strictly opposing influences on behavior. The dual impacts of nature and nurture in biology should become increasingly clear as students progress through your course. This chapter permits greater exploration of the roles of and interactions between genetic and environmental factors.
Teaching Tips
Consider the following analogy to help illustrate proximate and ultimate causes of behavior. If you write a term on the board during lecture, students are likely to write the term down in their notes. The proximate cause is a cue from you, the advantages of doing well on exams and good grades in general is more like an ultimate cause.
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6. 35.1 Behavioral ecologists ask both proximate and ultimate questions
The questions investigated by behavioral ecologists fall into two broad categories.
1. Proximate questions concern the immediate reason for the behavior.
How is it triggered by stimuli (environmental cues that cause a response)?
What physiological or anatomical mechanisms play a role?
What underlying genetic factors are at work?
Proximate causes are the answers to such questions about the immediate mechanism for behavior.
2. Ultimate questions address why a particular behavior occurs. Ultimate causes are the evolutionary explanations for behavior.
Student Misconceptions and Concerns
Students may misunderstand inherited factors and the environment as strictly opposing influences on behavior. The dual impacts of nature and nurture in biology should become increasingly clear as students progress through your course. This chapter permits greater exploration of the roles of and interactions between genetic and environmental factors.
Teaching Tips
Consider the following analogy to help illustrate proximate and ultimate causes of behavior. If you write a term on the board during lecture, students are likely to write the term down in their notes. The proximate cause is a cue from you, the advantages of doing well on exams and good grades in general is more like an ultimate cause.
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7. 35.2 Fixed action patterns are innate behaviors
Lorenz and Tinbergen were among the first to demonstrate the importance of innate behavior, behaviors that are
under strong genetic control and
are performed in virtually the same way by all individuals of a species.
Student Misconceptions and Concerns
Students may misunderstand inherited factors and the environment as strictly opposing influences on behavior. The dual impacts of nature and nurture in biology should become increasingly clear as students progress through your course. This chapter permits greater exploration of the roles of and interactions between genetic and environmental factors.
Teaching Tips
In Module 35.2, the authors make the following analogy. A fixed action pattern is like the series of steps performed automatically by a coffee vending machine. After money is inserted and a selection is made, a cup drops into place and coffee is dispensed, perhaps along with sugar and cream, depending on which button was pushed (that is, which particular fixed action pattern was triggered). You might challenge your students to suggest other examples drawn from their daily lives.
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8. 35.2 Fixed action patterns are innate behaviors
Many of Lorenz’s and Tinbergen’s studies were concerned with behavioral sequences called fixed action patterns (FAPs),
an unchangeable series of actions
triggered by a specific stimulus.
Once initiated, the sequence is performed in its entirety, regardless of any changes in circumstances.
Examples include
reproductive behaviors and
behaviors that must be done correctly the first time to survive, such as a young chick hatched out on a cliff ledge, starting to fly.
Student Misconceptions and Concerns
Students may misunderstand inherited factors and the environment as strictly opposing influences on behavior. The dual impacts of nature and nurture in biology should become increasingly clear as students progress through your course. This chapter permits greater exploration of the roles of and interactions between genetic and environmental factors.
Teaching Tips
In Module 35.2, the authors make the following analogy. A fixed action pattern is like the series of steps performed automatically by a coffee vending machine. After money is inserted and a selection is made, a cup drops into place and coffee is dispensed, perhaps along with sugar and cream, depending on which button was pushed (that is, which particular fixed action pattern was triggered). You might challenge your students to suggest other examples drawn from their daily lives.
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9. Figure 35.2A
Figure 35.2A A graylag goose retrieving an egg—a FAP 9

10. I think it’s your turn now!
Figure 35.2B
I think it’s your
turn now!
Figure 35.2B A pair of king penguins transferring their egg 10

11. 35.3 Behavior is the result of both genetic and environmental factors
Animal behavior often involves a combination of genetic programming and environmental factors.
Genetic engineering has been used to investigate genes that influence behavior. Genes have been identified that govern
learning and memory,
internal clocks,
courtship, and
mating behaviors.
Student Misconceptions and Concerns
1. Students may misunderstand inherited factors and the environment as strictly opposing influences on behavior. The dual impacts of nature and nurture in biology should become increasingly clear as students progress through your course. This chapter permits greater exploration of the roles of and interactions between genetic and environmental factors.
2. Distinguishing between proximate and ultimate causes may pose a challenge for some students. Students may imagine that organisms engage in behaviors intentionally, acting on a foresight far beyond their intellectual capacity. In fact, proximate causes reflect the immediate mechanism for a behavior that has been favored by natural selection (ultimate causes) with consequences that may occur much later in an organism’s life. For example, animal migrations may be triggered by immediate environmental cues (proximate causes). Do animals migrate because of a vision of a better place far away, or because migration has been adaptive in prior generations of their species (ultimate causes)?
Teaching Tips
Module 35.3 describes the dual influence of genetics and the environment in shaping behavior and other phenotypic characteristics. You might note that despite the fact that identical twins share the same set of genes, phenotypic differences occur. Furthermore, as the module also notes, in some reptile species the sex of offspring is determined by the incubation temperature of the eggs rather than by genetics.
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12. 35.3 Behavior is the result of both genetic and environmental factors
Cross-fostering experiments are useful for studying environmental factors that affect behavior.
Studies of rats reveal that behavioral changes can be passed to future generations,
NOT through genes, but through the social environment.
Interactions with the mother change the pattern of gene expression in the pups, thus affecting the development of parts of the neuroendocrine system that regulate the fight or flight response. (Remember “lick your pups?)
Student Misconceptions and Concerns
1. Students may misunderstand inherited factors and the environment as strictly opposing influences on behavior. The dual impacts of nature and nurture in biology should become increasingly clear as students progress through your course. This chapter permits greater exploration of the roles of and interactions between genetic and environmental factors.
2. Distinguishing between proximate and ultimate causes may pose a challenge for some students. Students may imagine that organisms engage in behaviors intentionally, acting on a foresight far beyond their intellectual capacity. In fact, proximate causes reflect the immediate mechanism for a behavior that has been favored by natural selection (ultimate causes) with consequences that may occur much later in an organism’s life. For example, animal migrations may be triggered by immediate environmental cues (proximate causes). Do animals migrate because of a vision of a better place far away, or because migration has been adaptive in prior generations of their species (ultimate causes)?
Teaching Tips
Module 35.3 describes the dual influence of genetics and the environment in shaping behavior and other phenotypic characteristics. You might note that despite the fact that identical twins share the same set of genes, phenotypic differences occur. Furthermore, as the module also notes, in some reptile species the sex of offspring is determined by the incubation temperature of the eggs rather than by genetics.
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13. High-interaction mother Low-interaction mother
Figure 35.3
High-interaction mother
Low-interaction mother
Pups become relaxed adults
Pups become fearful adults
Female pups become high-interaction mothers
Female pups become low-interaction mothers
Figure 35.3 A cross-fostering experiment with rats
Cross-fostering experiment
Pups become relaxed adults
Pups become fearful adults 13

14. 35.4 Habituation is a simple type of learning
Learning is modification of behavior as a result of specific experiences.
Learning enables animals to change their behaviors in response to changing environmental conditions.
There are various forms of learning, ranging from
a simple behavioral change in response to a single stimulus to
complex problem solving using entirely new behaviors.
Student Misconceptions and Concerns
1. Many students confuse the changes that occur during an individual’s lifetime with evolutionary change in a species. These individual “adaptations to the environment” can reinforce Lamarckian misconceptions.
2. Students may not have considered the general ability of animals to engage in behavioral responses to their environment and the more limited ability of plants to do likewise. Students might not have considered the different mechanisms that plants and animals employ to move within ecosystems (see Modules 33.9–33.13).
Teaching Tips
1. Although it is important to stress the diverse examples of learning in animals, students tend to understand concepts best by first applying them to their own experiences. Many of the teaching tips below provide examples of learning that occur in our daily lives.
2. While discussing habituation, draw students’ attention to the various sounds within your classroom that they might otherwise have “tuned out.” Also point out that students might not be aware of the texture of the pen or pencil they are holding, the firmness of the seat, or the position of their feet on the floor.
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15. 35.4 Habituation is a simple type of learning
Habituation is one of the simplest forms of learning.
An animal learns not to respond to a repeated stimulus that conveys little or no information.
In terms of ultimate causation, habituation may increase fitness by allowing an animal’s nervous system to focus on stimuli that signal
food,
mates, or
real danger.
Student Misconceptions and Concerns
1. Many students confuse the changes that occur during an individual’s lifetime with evolutionary change in a species. These individual “adaptations to the environment” can reinforce Lamarckian misconceptions.
2. Students may not have considered the general ability of animals to engage in behavioral responses to their environment and the more limited ability of plants to do likewise. Students might not have considered the different mechanisms that plants and animals employ to move within ecosystems (see Modules 33.9–33.13).
Teaching Tips
1. Although it is important to stress the diverse examples of learning in animals, students tend to understand concepts best by first applying them to their own experiences. Many of the teaching tips below provide examples of learning that occur in our daily lives.
2. While discussing habituation, draw students’ attention to the various sounds within your classroom that they might otherwise have “tuned out.” Also point out that students might not be aware of the texture of the pen or pencil they are holding, the firmness of the seat, or the position of their feet on the floor.
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16. 35.5 Imprinting requires both innate behavior and experience
Imprinting is
generally irreversible learning and
limited to a specific phase in an animal’s life called a sensitive period.
Examples include
a young bird learning to identify its parents and
song development in birds.
Student Misconceptions and Concerns
1. Many students confuse the changes that occur during an individual’s lifetime with evolutionary change in a species. These individual “adaptations to the environment” can reinforce Lamarckian misconceptions.
2. Students may not have considered the general ability of animals to engage in behavioral responses to their environment and the more limited ability of plants to do likewise. Students might not have considered the different mechanisms that plants and animals employ to move within ecosystems (see Modules 33.9–33.13).
Teaching Tips
1. Although it is important to stress the diverse examples of learning in animals, students tend to understand concepts best by first applying them to their own experiences. Many of the teaching tips below provide examples of learning that occur in our daily lives.
2. Students might wonder why birds have an imprinting period in which they learn to identify their mother. Why, students might wonder, don’t geese simply have an innate ability to recognize an adult female goose? The plasticity of imprinting permits offspring to identify their mother in particular (who has a greater genetic stake in their survival), rather than any adult female.
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17. Video: Ducklings Student Misconceptions and Concerns
Student Misconceptions and Concerns
1. Many students confuse the changes that occur during an individual’s lifetime with evolutionary change in a species. These individual “adaptations to the environment” can reinforce Lamarckian misconceptions.
2. Students may not have considered the general ability of animals to engage in behavioral responses to their environment and the more limited ability of plants to do likewise. Students might not have considered the different mechanisms that plants and animals employ to move within ecosystems (see Modules 33.9–33.13).
Teaching Tips
1. Although it is important to stress the diverse examples of learning in animals, students tend to understand concepts best by first applying them to their own experiences. Many of the teaching tips below provide examples of learning that occur in our daily lives.
2. Students might wonder why birds have an imprinting period in which they learn to identify their mother. Why, students might wonder, don’t geese simply have an innate ability to recognize an adult female goose? The plasticity of imprinting permits offspring to identify their mother in particular (who has a greater genetic stake in their survival), rather than any adult female.
Video: Ducklings
Use window controls to play
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18. Duck… duck… duck… goose!
Figure 35.5A
Duck… duck…
duck… goose!
Figure 35.5A Konrad Lorenz with geese imprinted on him 18

19. Frequency (kilocycles/second)
Figure 35.5B 5 4 3 2
Normal bird (imprinted) 1
Frequency (kilocycles/second) 5 4
Figure 35.5B The songs of male white-crowned sparrows that heard an adult sing during the sensitive period (top) and after the sensitive period (bottom) 3 2
Bird reared in isolation 1
Time (seconds) 19

20. Table 35.4
Table 35.4 Types of Learning 20

21. 35.7 Animal movement may be a simple response to stimuli or require spatial learning
Kinesis is a random movement in response to a stimulus. A kinesis may be
merely starting or stopping,
changing speed, or
turning more or less frequently.
Student Misconceptions and Concerns
1. Many students confuse the changes that occur during an individual’s lifetime with evolutionary change in a species. These individual “adaptations to the environment” can reinforce Lamarckian misconceptions.
2. Students may not have considered the general ability of animals to engage in behavioral responses to their environment and the more limited ability of plants to do likewise. Students might not have considered the different mechanisms that plants and animals employ to move within ecosystems (see Modules 33.9–33.13).
Teaching Tips
1. Although it is important to stress the diverse examples of learning in animals, students tend to understand concepts best by first applying them to their own experiences. Many of the teaching tips below provide examples of learning that occur in our daily lives.
2. Challenge your students to think of times when they engaged in kinesis and when they, by contrast, engaged in taxis. It may be difficult to identify an occurrence of true kinesis, when a person was not moving toward or away from some environmental factor. Whether turning away from the sun, moving toward a buffet, or waiting in line, most human movements are directed toward or away from at least one environmental factor. Struggling to identify an example of true kinesis helps students focus on the distinctions between kinesis and taxis.
3. Examples of spatial learning are abundant in a college environment. Most students (and faculty) travel to and from their classrooms not by following road signs, but by referencing environmental landmarks.
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22. That’s a rolypoly! Figure 35.7A
Figure 35.7A A sowbug (also known as a rolypoly or wood louse) 22

23. 35.7 Animal movement may be a simple response to stimuli or require spatial learning
Taxis is a response directed
toward (positive taxis) or
away from (negative taxis) a stimulus.
Many stream fish, such as trout, exhibit positive taxis in the current, automatically swimming or orienting in an upstream direction.
Student Misconceptions and Concerns
1. Many students confuse the changes that occur during an individual’s lifetime with evolutionary change in a species. These individual “adaptations to the environment” can reinforce Lamarckian misconceptions.
2. Students may not have considered the general ability of animals to engage in behavioral responses to their environment and the more limited ability of plants to do likewise. Students might not have considered the different mechanisms that plants and animals employ to move within ecosystems (see Modules 33.9–33.13).
Teaching Tips
1. Although it is important to stress the diverse examples of learning in animals, students tend to understand concepts best by first applying them to their own experiences. Many of the teaching tips below provide examples of learning that occur in our daily lives.
2. Challenge your students to think of times when they engaged in kinesis and when they, by contrast, engaged in taxis. It may be difficult to identify an occurrence of true kinesis, when a person was not moving toward or away from some environmental factor. Whether turning away from the sun, moving toward a buffet, or waiting in line, most human movements are directed toward or away from at least one environmental factor. Struggling to identify an example of true kinesis helps students focus on the distinctions between kinesis and taxis.
3. Examples of spatial learning are abundant in a college environment. Most students (and faculty) travel to and from their classrooms not by following road signs, but by referencing environmental landmarks.
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24. Direction of river current
Figure 35.7B
Direction of river current
Figure 35.7B Salmon exhibiting positive taxis to a current as they swim upstream to spawn 24

25. 35.7 Animal movement may be a simple response to stimuli or require spatial learning
In spatial learning, animals establish memories of landmarks in their environment that indicate the locations of
food,
nest sites,
prospective mates, and/or
potential hazards.
The digger wasp uses landmarks to keep track of her nests.
Student Misconceptions and Concerns
1. Many students confuse the changes that occur during an individual’s lifetime with evolutionary change in a species. These individual “adaptations to the environment” can reinforce Lamarckian misconceptions.
2. Students may not have considered the general ability of animals to engage in behavioral responses to their environment and the more limited ability of plants to do likewise. Students might not have considered the different mechanisms that plants and animals employ to move within ecosystems (see Modules 33.9–33.13).
Teaching Tips
1. Although it is important to stress the diverse examples of learning in animals, students tend to understand concepts best by first applying them to their own experiences. Many of the teaching tips below provide examples of learning that occur in our daily lives.
2. Challenge your students to think of times when they engaged in kinesis and when they, by contrast, engaged in taxis. It may be difficult to identify an occurrence of true kinesis, when a person was not moving toward or away from some environmental factor. Whether turning away from the sun, moving toward a buffet, or waiting in line, most human movements are directed toward or away from at least one environmental factor. Struggling to identify an example of true kinesis helps students focus on the distinctions between kinesis and taxis.
3. Examples of spatial learning are abundant in a college environment. Most students (and faculty) travel to and from their classrooms not by following road signs, but by referencing environmental landmarks.
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26. Figure 35.7C_s1
Nest 1
Figure 35.7C_s1 The nest-locating behavior of the digger wasp (step 1) 26

27. Nest No nest Nest 1 2 Figure 35.7C_s2
Figure 35.7C_s2 The nest-locating behavior of the digger wasp (step 2) 27

28. Nest No nest Nest Nest No nest Those scientists are braver than I am!
Figure 35.7C_s3
Those scientists
are braver than
I am!
Nest 1
No nest
Nest 2
Figure 35.7C_s3 The nest-locating behavior of the digger wasp (step 3)
Nest
No nest 3 28

29. 35.9 Animals may learn to associate a stimulus or behavior with a response
Associative learning is the ability to associate one environmental feature with another.
In one type of learning, an animal learns to link a particular stimulus to a particular outcome. For example, a dog may expect to go for a walk if the owner picks up the leash.
Trial-and-error learning is an animal’s ability to learn to associate one of its own behaviors with a positive or negative effect.
Memory is the key to all associative learning.
Student Misconceptions and Concerns
1. Many students confuse the changes that occur during an individual’s lifetime with evolutionary change in a species. These individual “adaptations to the environment” can reinforce Lamarckian misconceptions.
2. Students may not have considered the general ability of animals to engage in behavioral responses to their environment and the more limited ability of plants to do likewise. Students might not have considered the different mechanisms that plants and animals employ to move within ecosystems (see Modules 33.9–33.13).
Teaching Tips
1. Although it is important to stress the diverse examples of learning in animals, students tend to understand concepts best by first applying them to their own experiences. Many of the teaching tips below provide examples of learning that occur in our daily lives.
2. Associative learning can lead to misleading conclusions. Correlated factors may not have a cause-and-effect relationship. Challenge your students to think of examples of misleading correlations.
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30. Ouch! That smarts! Figure 35.9
Figure 35.9 Trial-and-error learning by a dog
Ouch!
That smarts! 30

31. SURVIVAL AND REPRODUCTIVE SUCCESS
SURVIVAL AND REPRODUCTIVE SUCCESS
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32. 35.12 Behavioral ecologists use cost-benefit analysis to study foraging
Animals forage in a great many ways.
Some animals, such as crows, are feeding “generalists.”
Other animals, such as koalas, are feeding “specialists.”
The mechanism that enables an animal to find particular foods efficiently is called a search image.
Student Misconceptions and Concerns
Some students may believe that humans are somehow exceptional and that their behavior is not governed by the principles of animal behavior. Other students may acknowledge these associations, but remain skeptical when it comes to individual examples. Behaviors, just like our biochemical and cellular structure, reveal our close kinship with animals and our descent from common ancestors.
Teaching Tips
1. The concept of a search image is familiar to most people, although it may not go by this name. Ask your students if they can recall searching for a parent or friend, perhaps somewhere in a large store. As they scanned the crowd of people, do they remember watching for some particular characteristic of the person they were looking for, perhaps their height, the color of their clothing, or another distinctive feature? When we ask for help finding something we have lost, the first question we often answer is “What does it look like?” The description of the lost item or person helps the person who hears it form a search image.
2. All of us engage in some sort of cost-benefit analysis when selecting a restaurant. Distance, price, and the type of meal are all considered. Although a meal several hundred miles away might be better, few of us would travel such a distance.
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33. 35.12 Behavioral ecologists use cost-benefit analysis to study foraging
Animals with food choices face trade-offs involved in selection. The amount of energy may vary considerably in
locating,
capturing, and
preparing prey for consumption.
Student Misconceptions and Concerns
Some students may believe that humans are somehow exceptional and that their behavior is not governed by the principles of animal behavior. Other students may acknowledge these associations, but remain skeptical when it comes to individual examples. Behaviors, just like our biochemical and cellular structure, reveal our close kinship with animals and our descent from common ancestors.
Teaching Tips
1. The concept of a search image is familiar to most people, although it may not go by this name. Ask your students if they can recall searching for a parent or friend, perhaps somewhere in a large store. As they scanned the crowd of people, do they remember watching for some particular characteristic of the person they were looking for, perhaps their height, the color of their clothing, or another distinctive feature? When we ask for help finding something we have lost, the first question we often answer is “What does it look like?” The description of the lost item or person helps the person who hears it form a search image.
2. All of us engage in some sort of cost-benefit analysis when selecting a restaurant. Distance, price, and the type of meal are all considered. Although a meal several hundred miles away might be better, few of us would travel such a distance.
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34. A “cost vs. benefit” analysis
35.12 Behavioral ecologists use cost-benefit analysis to study foraging
Optimal foraging theory predicts that an animal’s feeding behavior should provide
maximal energy gain with minimal energy expense and
minimal risk of being eaten while foraging.
In England, a researcher tested part of this theory by studying insectivorous birds called wagtails, which often eat dung flies.
A “cost vs. benefit” analysis
Student Misconceptions and Concerns
Some students may believe that humans are somehow exceptional and that their behavior is not governed by the principles of animal behavior. Other students may acknowledge these associations, but remain skeptical when it comes to individual examples. Behaviors, just like our biochemical and cellular structure, reveal our close kinship with animals and our descent from common ancestors.
Teaching Tips
1. The concept of a search image is familiar to most people, although it may not go by this name. Ask your students if they can recall searching for a parent or friend, perhaps somewhere in a large store. As they scanned the crowd of people, do they remember watching for some particular characteristic of the person they were looking for, perhaps their height, the color of their clothing, or another distinctive feature? When we ask for help finding something we have lost, the first question we often answer is “What does it look like?” The description of the lost item or person helps the person who hears it form a search image.
2. All of us engage in some sort of cost-benefit analysis when selecting a restaurant. Distance, price, and the type of meal are all considered. Although a meal several hundred miles away might be better, few of us would travel such a distance.
© 2012 Pearson Education, Inc. 34

35. Figure 35.12A
Figure 35.12A A wagtail 35

36. Figure 35.12B
Figure 35.12B A dung fly 36

37. Wagtail calorie intake per second of handling time
Figure 35.12C 16 14
Wagtail calorie intake per second of handling time 12 10
Figure 35.12C The relationship between the calories gained by the wagtail and the size of its prey (the dung fly) 5 6 7 8 9 10
Dung fly body length (mm) 37

38. Dung flies available (Total  460)
Figure 35.12D 50
Dung flies available (Total  460) 40
Dung flies eaten (Total  252) 30
Percent of total 20 10
Figure 35.12D The prey sizes selected by wagtails compared with the prey sizes available 5 6 7 8 9 10
Dung fly body length (mm) 38

39. 35.21 EVOLUTION CONNECTION: Altruistic acts can often be explained by the concept of inclusive fitness
Many social behaviors are selfish because natural selection favors behaviors that maximize an individual’s
survival and
reproductive success.
Altruism is defined as behavior that reduces an individual’s fitness while increasing the fitness of others in the population.
Student Misconceptions and Concerns
Students who have watched enough footage of animal behavior on television might believe that most animal disputes are resolved through dangerous combat. Modules 35.17–35.23 include many examples of agonistic behavior that reduce the likelihood of direct combat, perhaps through displays, vocalizations, or chemical communication. Peaceful strategies save energy and lives, although they seldom boost television ratings.
Teaching Tips
Before addressing the content of Module 35.21, challenge your students to explain how you can pass along your genes if you do not reproduce. Consider asking this question at the end of a lecture period, to be discussed at the start of the next class period.
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40. 35.21 EVOLUTION CONNECTION: Altruistic acts can often be explained by the concept of inclusive fitness
The concept of inclusive fitness describes an individual’s success at perpetuating its genes by
producing its own offspring and
helping close relatives, who likely share many of those genes, to produce offspring.
Natural selection favoring altruistic behavior that benefits relatives is called kin selection. Thus, genes for altruism may be propagated if individuals that benefit from altruistic acts are themselves carrying those genes.
Student Misconceptions and Concerns
Students who have watched enough footage of animal behavior on television might believe that most animal disputes are resolved through dangerous combat. Modules 35.17–35.23 include many examples of agonistic behavior that reduce the likelihood of direct combat, perhaps through displays, vocalizations, or chemical communication. Peaceful strategies save energy and lives, although they seldom boost television ratings.
Teaching Tips
Before addressing the content of Module 35.21, challenge your students to explain how you can pass along your genes if you do not reproduce. Consider asking this question at the end of a lecture period, to be discussed at the start of the next class period.
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41. Figure 35.21A
Figure 35.21A The queen of a naked mole rat colony nursing offspring while surrounded by other individuals of the colony 41

42. 35.21 EVOLUTION CONNECTION: Altruistic acts can often be explained by the concept of inclusive fitness
A classic study of Belding’s ground squirrels, which live in regions of the western United States, provided empirical support for kin selection.
Student Misconceptions and Concerns
Students who have watched enough footage of animal behavior on television might believe that most animal disputes are resolved through dangerous combat. Modules 35.17–35.23 include many examples of agonistic behavior that reduce the likelihood of direct combat, perhaps through displays, vocalizations, or chemical communication. Peaceful strategies save energy and lives, although they seldom boost television ratings.
Teaching Tips
Before addressing the content of Module 35.21, challenge your students to explain how you can pass along your genes if you do not reproduce. Consider asking this question at the end of a lecture period, to be discussed at the start of the next class period.
© 2012 Pearson Education, Inc. 42

43. Percentage of times females give alarm call Relatives living nearby
Figure 35.21B 80 60
Percentage of times females give alarm call 40
Figure 35.21B The frequency of alarm calls by Belding’s ground squirrels (inset photo) when close relatives are nearby or absent 20
Daughters or granddaughters
No relatives
Mothers or sisters
No relatives
Relatives living nearby 43

44. Percentage of times females give alarm call
Figure 35.21B_1 80 60
Percentage of times females give alarm call 40 20
Figure 35.21B_1 The frequency of alarm calls by Belding’s ground squirrels when close relatives are nearby or absent (part 1)
Daughters or granddaughters
No relatives
Mothers or sisters
No relatives
Relatives living nearby 44

45. Figure 35.21B_2
Figure 35.21B_2 The frequency of alarm calls by Belding’s ground squirrels when close relatives are nearby or absent (part 2) 45