Campbell Biology Chapter 51 Review: Animal Behavior

51.1 Triggers, rhythms and animal signals

pp. 1118–1122

On the AP exam? Yes

Topic 8.1 tests how animals respond to cues and pass information with visual, sound, touch, electrical and chemical signals. Words like fixed action pattern, sign stimulus and proximate versus ultimate cause are handy background but aren't tested by name.

In the course: Topic 8.1 Responses to the Environment (notes, videos and more questions)

Key points

A behavior is an action an animal takes when it senses a change inside or around it. The nervous system directs it, and muscles or glands carry it out. Because behavior affects survival and reproduction, natural selection shapes it like any other trait.
Biologists ask two kinds of questions about a behavior. Proximate questions ask how: what sets it off, which nerves and hormones run it, and how it develops. Ultimate questions ask why: how it helps the animal leave offspring and how it evolved. Niko Tinbergen split these into four questions.
A fixed action pattern is an unlearned series of actions that a specific trigger, known as a sign stimulus, switches on. Once it starts, it usually plays out to the end, even if the cue is taken away.
Migrating animals find their way with several cues: the sun (corrected for time of day by an internal clock), the stars at night and Earth's magnetic field. How animals sense magnetism is still being studied; light-sensitive proteins in the eye and tiny iron-rich crystals are the leading ideas.
A circadian rhythm repeats about every 24 hours and keeps going even when conditions stay constant, though light normally resets it each day. Yearly (circannual) cycles like breeding seasons are usually timed by day length, and a few behaviors follow the moon and tides instead.
Communication means one animal sends a signal that changes another's behavior. Signals can be visual, chemical, tactile (touch) or auditory, and some fish use electrical pulses. A complex behavior can be a chain in which each response becomes the cue for the next step.
Pheromones are chemical signals between members of the same species, and they can work at tiny concentrations. Honeybee foragers dance on the comb to tell nestmates the direction and distance to food. The kind of signal a species relies on tends to suit its habitat: night-active animals lean on smell and sound rather than sight.

Key terms (14)

behavior: Any action an animal takes in reaction to something it senses, like singing, fleeing or courting. The nervous system directs it and muscles or glands carry it out.
proximate cause: The "how" of a behavior: the trigger, the nerves and hormones involved, and how it develops in the individual.
ultimate cause: The "why" of a behavior: how it raises survival or reproduction and how it evolved over many generations.
behavioral ecology: The field that studies behavior in light of ecology and evolution, asking how behaviors help animals succeed in their environments.
fixed action pattern: An unlearned series of actions that, once a specific cue starts it, usually runs all the way through, even if the cue disappears.
sign stimulus: The simple outside cue, such as a color, shape or sound, that switches on a fixed action pattern.
migration: A long trip an animal makes on a regular schedule, often each year between a breeding area and a wintering area.
circadian rhythm: A roughly 24-hour cycle of activity and sleep driven by an internal clock. It keeps going in constant conditions, but daylight normally resets it.
circannual rhythm: A behavior or body cycle that repeats once a year, such as breeding or migrating, usually timed by changes in day length.
signal: Anything one animal produces, like a sound, scent, color or touch, that changes what another animal does.
animal communication: Sending and receiving signals between animals. It can be visual, chemical, tactile, auditory or electrical.
pheromone: A chemical released by an animal that affects the behavior or body of others of the same species, often in tiny amounts.
waggle dance: A honeybee forager's run on the comb that shows nestmates where food is. The angle of the run gives direction and its length gives distance.
stimulus-response chain: A sequence in which each animal's response becomes the cue for the next action, as in many courtship rituals.

Check yourself: 51.1 Triggers, rhythms and animal signals

4 questions on 51.1 Triggers, rhythms and animal signals. Pick an answer to see if you got it, and why.

Question 1 of 4

Male tree frogs of one species call loudly on summer nights. Which question about this calling asks about its ultimate cause?

Question 2 of 4

Newly hatched chicks of a songbird species stretch their necks and open their beaks wide whenever the nest shakes. They do this before their eyes open, they do it the first time the nest moves, and they do it just as strongly when a researcher taps the nest with a pencil. Which term best describes this begging response?

Question 3 of 4

Workers of an ant species that find food lay a chemical trail back to the nest, and nestmates follow it. The trail chemical evaporates within a few minutes unless more ants keep adding to it. What is the most likely advantage of a trail that fades so quickly?

Question 4 of 4

Mice are moved from a normal light–dark schedule into constant darkness. Their running-wheel activity keeps a regular daily pattern, but it starts about 20 minutes earlier each day than it did the day before. Which conclusion is best supported?

0 of 4 answered

51.2 Learning and the role of experience

pp. 1123–1128

On the AP exam? Yes

Topic 8.1 tests the difference between innate and learned behavior and why natural selection favors both, and Topic 5.5 covers the environment shaping a phenotype. Names of learning types, like imprinting or operant conditioning, are background.

In the course: Topic 8.1 Responses to the Environment, Topic 5.5 Environmental Effects on Phenotype (notes, videos and more questions)

Key points

Innate behavior appears in its full form without practice or lessons, so members of a species perform it alike even when raised in very different ways. Learned behavior changes based on what an individual has experienced.
To separate the effects of genes and surroundings, researchers raise young with adults of another species (cross-fostering) or compare identical twins raised apart and together. These studies usually find that both genes and environment matter, and early experience can even change how an animal later raises its own young.
Imprinting is a lasting attachment, for example to a parent, that can only form during a short sensitive (or critical) window early in life. The readiness to imprint is built in, but what the young animal meets during that window decides what it attaches to.
Spatial learning means remembering the layout of the environment, such as where the nest or food is, often by using landmarks. A cognitive map is a mental picture of how places relate to each other, which lets an animal take new shortcuts.
In associative learning, an animal links one thing with another. In classical conditioning, a neutral cue becomes linked with an outcome; in operant (trial-and-error) conditioning, an animal links its own action with a reward or punishment. Animals form most easily the links that would be useful in their natural lives.
Cognition (awareness, reasoning, memory and judgment) and problem solving show up in many animals, including birds and even insects, not only in primates.
Some learning happens in stages within limits set by genes, like a young songbird memorizing its species' song and then practicing until it matches. Social learning, picking up behavior by watching others, lets new habits spread through a group and is the basis of culture.

Key terms (15)

innate behavior: Behavior that develops the same way in nearly all members of a species, without needing practice or experience.
learning: A lasting change in behavior that comes from experience.
cross-fostering study: An experiment where young of one species are raised by adults of another, to see how much the rearing environment changes behavior.
twin study: Comparing identical twins raised together with those raised apart, to sort out how much genes and environment each affect a trait.
imprinting: Learning, in a short window early in life, that ties a young animal's behavior to one specific individual or thing, like a parent, often for life.
sensitive period: A limited stage of development when a certain kind of learning, like imprinting, can happen. Also called a critical period.
spatial learning: Learning and remembering the layout of your surroundings, such as where food, shelter or the nest is.
cognitive map: A mental representation of how objects and places are arranged relative to each other, which allows flexible routes and shortcuts.
associative learning: Learning that two things go together, like a cue and a result, or an action and its reward.
classical conditioning: Associative learning in which a neutral cue comes to trigger a response because it reliably comes just before an outcome.
operant conditioning: Trial-and-error learning in which an animal repeats actions that were rewarded and avoids ones that were punished.
cognition: The mental work of knowing and thinking: being aware, reasoning, remembering and judging.
problem solving: Figuring out a way to reach a goal when the direct route to it is blocked.
social learning: Learning by watching or interacting with others of your species instead of by your own trial and error.
culture: Behaviors and know-how that a group shares and hands on as members learn from one another, like tool-use habits that differ between populations.

Check yourself: 51.2 Learning and the role of experience

4 questions on 51.2 Learning and the role of experience. Pick an answer to see if you got it, and why.

Question 1 of 4

Mud-dauber wasp larvae were collected as eggs and raised alone in the lab, so they never saw an adult or a nest. As adults, they built mud nests with the same shape, size and number of cells as wild wasps, and did it correctly on the first try. What does this best show?

Question 2 of 4

Hatchery salmon were exposed to a harmless odor chemical at different ages. Years later, adults returning from the sea were counted at two streams, one of which was scented with that chemical (invented data). Age when exposed | Chose the scented stream (%) Not exposed (control) | 49 Young fry | 52 Smolts (just before going to sea) | 91 Adults | 50 Which explanation best fits these results?

Question 3 of 4

Which example is operant conditioning?

Question 4 of 4

Quail (which find food mainly by sight) and ferrets (which rely mainly on smell and taste) were given water that was both dyed blue and sour, then made mildly ill (invented results). Before this, both species drank such water readily. Afterward, the quail avoided blue water but not sour water, while the ferrets avoided sour water but not blue water. Which explanation fits best?

0 of 4 answered

51.3 Foraging, mating and selection on behavior

pp. 1128–1134

On the AP exam? Background

Topic 8.1 tests the big idea here: natural selection favors behaviors that raise survival and reproduction. Optimal foraging, mating systems, sexual selection and game theory aren't named in the current course, so treat them as background.

In the course: Topic 8.1 Responses to the Environment, Topic 7.2 Natural Selection (notes, videos and more questions)

Key points

Foraging is the whole job of getting food, from finding and identifying it to catching and eating it. Since food fuels survival and reproduction, selection should improve foraging, and lab experiments with fruit flies have shown foraging behavior evolving when living conditions change.
The optimal foraging model says selection favors foraging that gets the most benefit (usually energy) for the least cost. Costs include energy and time spent and the risk of being eaten, so animals often give up some food to stay safe.
Mating systems differ. In promiscuous species there are no lasting pairs. Monogamous species pair one male with one female. Polygamous species include polygyny (one male, several females) and polyandry (one female, several males).
Sexual dimorphism, how different the sexes look, tends to track the mating system. Males and females of monogamous species often look alike; in polygynous species males are usually larger or showier, and in polyandrous species the females are.
What the young need shapes mating systems. Helpless chicks that need constant feeding favor two parents, which is one reason most birds are socially monogamous (DNA tests show extra-pair chicks are still common). Animals don't consciously weigh this; selection has favored care where it pays off.
Certainty of paternity also matters. Males can be surer the young are theirs when eggs are fertilized outside the body as they're laid, and male care is more common in such species. With internal fertilization, males often guard mates or compete through sperm.
Sexual selection comes in two forms: intersexual selection, where one sex (often females) chooses mates by their traits, and intrasexual selection, where members of one sex compete, often in ritualized agonistic contests. When the payoff of a behavior depends on how many others use it, game theory and frequency-dependent selection explain how several male types can persist.

Key terms (15)

foraging: Everything an animal does to get food, from finding and identifying it to catching and eating it.
optimal foraging model: The idea that selection favors feeding behavior that gives the most benefit for the least cost, including energy, time and danger.
promiscuous: A mating system with no lasting pair-bonds, where individuals mate with several partners.
monogamous: A mating system in which one male and one female pair up, often raising young together.
polygamous: A mating system in which one individual of one sex mates with several individuals of the other sex.
polygyny: A polygamous system where one male mates with several females.
polyandry: A polygamous system where one female mates with several males, who often do much of the parenting.
sexual dimorphism: A difference between males and females of a species in size, color or other features beyond the reproductive organs.
certainty of paternity: How likely it is that the young a male helps raise are really his own offspring.
sexual selection: Natural selection in which some individuals leave more offspring because they are better at getting mates.
intersexual selection: Sexual selection by mate choice: members of one sex pick partners based on traits of the other sex.
intrasexual selection: Sexual selection by competition: members of the same sex fight or display against each other for mates.
agonistic behavior: Threats, displays or fights between rivals over something both want, such as food, space or a mate. Many are settled by display alone, without injury.
mate-choice copying: Choosing a mate partly because other individuals have chosen that same mate. It's a form of social learning.
game theory: A math tool for working out which behavior pays best when its payoff changes with what everyone else in the population is doing.

Check yourself: 51.3 Foraging, mating and selection on behavior

4 questions on 51.3 Foraging, mating and selection on behavior. Pick an answer to see if you got it, and why.

Question 1 of 4Calculator allowed

A squirrel can eat three sizes of nut. Small nuts give 2 kJ of energy and take 10 seconds to open, medium nuts give 6 kJ and take 20 seconds, and large nuts give 9 kJ and take 45 seconds. If time spent opening nuts is the main cost, which choice does the optimal foraging model predict?

Question 2 of 4

Question 3 of 4

In a newly studied parrot species, males and females are almost impossible to tell apart, and both parents bring food to the nestlings. Which mating system is most likely?

Question 4 of 4

In a damselfly species with internal fertilization, a male stays clasped to a female after mating until she has laid her eggs, even though he could leave to find other females. Which explanation is most consistent with natural selection?

0 of 4 answered

51.4 Genes, behavior and helping relatives

pp. 1134–1139

On the AP exam? Yes

Topic 8.1 tests cooperative behavior and why helping relatives can be favored (kin selection). Hamilton's rule, the coefficient of relatedness and the specific behavior genes are background, but working the rB > C math is good practice.

In the course: Topic 8.1 Responses to the Environment, Topic 7.2 Natural Selection, Topic 6.5 Regulation of Gene Expression (notes, videos and more questions)

Key points

Genes shape behavior in different ways. In fruit flies, one key regulatory gene with male and female versions sets up the wiring for the whole male courtship ritual. Other behaviors, like the courtship songs of some insects, depend on many genes, each affecting one feature.
A single gene can make a big difference. In voles, how much of a receptor for the hormone vasopressin is made in certain brain areas helps decide whether males form pair-bonds; adding more receptor made males of a non-bonding species bond. Later work shows other hormones and genes, like oxytocin and its receptor, matter too.
If behavior differs between populations in a way that matches their surroundings, and lab-raised offspring keep their parents' behavior, the difference is likely genetic and shaped by past selection. Such changes, like a new migration route, can evolve within decades.
Altruism means helping others at a cost to yourself: the helper's survival or reproduction goes down while the others' goes up. At first glance, natural selection should get rid of it.
Inclusive fitness counts both an individual's own offspring and the extra offspring its help lets relatives produce. Kin selection is natural selection favoring behavior that helps relatives, because relatives carry copies of many of the same alleles.
Hamilton's rule says helping is favored when rB > C. Here r is the coefficient of relatedness (0.5 for a parent and child or full siblings, 0.25 for half siblings or a grandparent and grandchild, 0.125 for first cousins), B is the extra offspring the helped relative has, and C is the offspring the helper gives up.
Helping non-relatives can pay if the favor is returned later (reciprocal altruism). It's rare outside species with stable groups where the same individuals meet again and again, and it can be kept stable by strategies like tit for tat. Human behavior is shaped by genes too, but learning and culture make it unusually flexible.

Key terms (11)

master regulatory gene: A gene that controls many other genes. In fruit flies, one such gene directs the brain wiring behind male courtship.
pair-bond: A lasting partnership between a male and a female that mate and often raise young together.
altruism: Behavior that costs the helper some of its own survival or reproduction while raising the fitness of others.
inclusive fitness: An individual's total genetic contribution: its own offspring plus the extra offspring of relatives that its help makes possible.
kin selection: Natural selection that favors helping relatives, since relatives share many of the helper's alleles.
coefficient of relatedness (r): The average fraction of alleles two relatives share because of common ancestry, like 0.5 for full siblings.
Hamilton's rule: Helping a relative is favored when rB > C: relatedness times the benefit to the relative beats the cost to the helper.
reciprocal altruism: Helping a non-relative who is likely to return the favor later. It needs repeated meetings between the same individuals.
tit for tat: A strategy in repeated encounters: cooperate the first time, then do whatever your partner did to you last time.
cheating: In reciprocal altruism, accepting help but not returning it when the chance comes.
sociobiology: The study of social behavior, including human behavior, as a product of natural selection acting on genes.

Check yourself: 51.4 Genes, behavior and helping relatives

4 questions on 51.4 Genes, behavior and helping relatives. Pick an answer to see if you got it, and why.

Question 1 of 4Calculator allowed

In a cooperatively breeding fish, a female skips breeding for a season to guard her full sister's brood. Guarding adds 3 surviving young to the sister's brood (B = 3) and costs the helper 1 surviving young of her own (C = 1). Which change would make Hamilton's rule no longer favor this help?

Question 2 of 4

In a colonial seabird, adults sometimes dive at a gull that is raiding a nest, which puts the defender at risk of injury. Researchers recorded how often a nearby adult joined the defense, depending on whose nest was being raided (invented data). Owner of the raided nest | Nearby adults that joined the defense (%) Its own nest | 71 A full sibling's or parent's nest | 64 An unrelated neighbor's nest | 19 Which hypothesis do these data best support?

Question 3 of 4

On one Pacific island, a parasitic fly finds male field crickets by homing in on their songs. Within about 20 generations, most males there became "silent": their wings no longer make sound. In a population where the fly is absent, almost all males sing. Eggs from both islands were raised under identical lab conditions, and silent males appeared only among offspring from the fly island. What do these results most strongly suggest?

Question 4 of 4

Which situation is most likely to favor the evolution of reciprocal altruism?

0 of 4 answered