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Ch 51 Notes from Campbell & Reese Biology
8th
ed. (For AP Bio.)
I Introduction: What is Animal behavior?
1. Behavior -nervous system’s response to a stimulu; carried out by muscular or hormonal systems
2. Behavior helps an animal get food, find mate for reproduction, maintain homeostasis
3. Behavior is subject to natural selection
A. Discrete sensory inputs can stimulate both simple and complex behaviors
1. Ethology study of animal behavior, particularly in natural environments
2. Niko Tinbergen – said ask four questions about a behavior:
Q1. What stimulus elicits the behavior, & what physiological mechanisms mediate response?
Q2. How does experience during growth & development influence response mechanisms?
Q3. How does the behavior aid survival and reproduction?
Q4. What is the behavior’s evolutionary history?
3. Causes of behavior
a. Proximate causation- How a behavior happens; Most immediate reason for it
1) Environmental stimuli that trigger a behavior
2) Genetic, physiological, and anatomical mechanisms that bring about a behavior
b. Ultimate causation- Why a behavior happens: focuses on Ultimate reason for the behavior
4. Behavioral ecology- study of the ecological and evolutionary basis for animal behavior; integrates
proximate and ultimate explanations for animal behavior
B. Fixed Action Patterns- sequence of unlearned, innate behaviors that is unchangeable
1. Once initiated, it is usually carried to completion
2. triggered by an external cue known as a sign stimulus
C. Oriented movement- Environmental cues trigger movement in a popular direction
1. Kinesis & taxis
a. Kinesis- a simple change in response to an environment.
b. Taxis-a mostly automatic oriented movement toward or away from a stimulus
1) Many stream fish exhibit a positive taxis; automatically swim in an upstream direction
2. Migration- a regular, long-distance change in location
a. Animals can orient themselves using
1) position of sun & their circadian clock, an internal 24-hour clock; part of nervous system
2) position of the North Star
3) Earth’s magnetic field
D. Behavioral Rhythms- behavior set according to internal or external signals
1. affected by circadian rhythm, a daily cycle of rest and activity
2. linked to changing seasons, or a circannual rhythm
3. linked to lunar cycles- For example, courtship in fiddler crabs occurs during the new and full moon
E. Animal Signals & communication
1. Signal- a behavior that causes a change in another animal’s behavior
2. Communication- the transmission and reception of signals
3. Animals communicate using visual, chemical, tactile, and auditory signals
Honeybees communicate with symbolic language
• A bee returning from the field performs a dance to communicate the position of a food source
F. Pheromones- chemical substances emitted by animal; communication through odors
1. effective at very low concentrations
2. alarm substance in an injured fish’s skin disperses into water; induces fright response among fish
III. Learning establishes specific links between experience and behavior
A. Innate behavior- developmentally fixed; genetically influenced
B. Learning- modification of behavior based on specific experience
C. Habituation- involves loss of responsiveness to stimuli that convey little or no information
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a. birds stop responding to alarm calls from their species if no actual attack follows signal
D. Imprinting- includes learning and innate components: generally irreversible
1. sensitive period- limited developmental phase: is the only time when certain behaviors can be learned
2. Example- imprinting young geese to follow their mother
 Konrad Lorenz- when baby geese spent the first few hours of their life with him, they imprinted on
him as their parent
3. Useful: Young whooping cranes imprint on humans in “crane suits” who lead crane migrations in
ultralight aircraft
E. Spatial learning- more complex; behavior based on experience with spatial structure of environment
 Niko Tinbergen showed digger wasps use landmarks to find nest entrances
F. Cognitive map- an internal representation of spatial relationships between objects in the surroundings
 Clark’s nutcrackers can find food hidden in caches located halfway between particular landmarks
G. Associative learning- animals associate one feature of their environment with another
1. Classical conditioning- associative learning- arbitrary stimulus is associated w/ reward or punishment
a. Ex. Dog repeatedly hears bell before being fed will salivate in anticipation at the bell’s sound
2. Operant conditioning- associative learning- animal learns to associate one of its behaviors with a
reward or punishment; It is also called trial-and-error learning
a. Ex a rat is fed after pushing a lever will learn to push the lever in order to receive food
b. Ex. a predator may learn to avoid prey associated with a painful experience
H. Cognition & problem solving
1. Cognition- “knowing”- may include awareness, reasoning, recollection, and judgment
a. Honeybees can distinguish “same” from “different”
2. Problem solving- devising a strategy to overcome an obstacle
a. chimpanzees can stack boxes to reach suspended food
3. Some animals learn by observing other individuals
a. chimpanzees learn to crack palm nuts with stones by copying older chimpanzees
I. Development of learned behaviors may occur in distinct stages
1. white-crowned sparrow memorizes the song of its species during an early sensitive period
2. learns to sing the song during a second learning phase
IV. Concept 51.3: Both genetic makeup and environment contribute to the development of behaviors
A. Animal behavior is governed by complex interactions between genetic and environmental factors
B. Experience & Behavior
1. Cross-fostering studies help identify contribution of environment to an animal’s behavior
2. A cross-fostering study places the young from one species in the care of adults from another species.
3. Different species of Cross-fostered mice developed some behaviors like their foster parents’
4. In humans, twin studies-compare relative influences of genetics and environment on behavior
C. Regulatory Genes & behavior
1. A master regulatory gene can control many behaviors
– a single gene controls behaviors of the male fruit fly courtship ritual
2. Multiple independent genes can contribute to a single behavior
– in green lacewings multiple independent genes govern different partss of the courtship song
D. Genetically Based Behavioral Variation in Natural Populations
1. If behavioral variation in a species corresponds to environmental variation, may be evidence of evolution
2. Case study: Variation in Migratory Patterns
a. Most blackcap birds breed in Germany & winter in Africa; some winter in Britain
b. The two pops. are genetically distinct
3. Case Study: Variation in Prey Selection
a. Coastal populations of western garter snakes eat banana slugs; inland populations rarely do.
b. Studies have shown that the differences in diet are genetic
c. Only one group can detect and respond to specific odor molecules produced by the banana slugs
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E. Influence of Single Locus variation
1. Differences at a single locus can sometimes have a large effect on behavior
a. For example, male prairie voles pair-bond with their mates, while male meadow voles do not
b. The level of a specific receptor for a neurotransmitter determines which behavioral pattern develops
V. Selection for individual survival and reproductive success can explain most behaviors
1. Genetic components of behavior evolve through natural selection
2. Behavior can affect fitness by influencing foraging and mate choice
A. Foraging Behavior
1. Foraging- food-obtaining behavior, includes recognizing, searching for, capturing, & eating food items
2. Natural selection refines behaviors that enhance the efficiency of feeding
B. Evolution of Foraging Behavior
1. In Drosophila melanogaster, variation in a gene dictates foraging behavior in the larvae
2. Larvae in high-density populations benefit from foraging farther for food, while larvae in low-density
populations benefit from short-distance foraging\
3. Natural selection favors different foraging behavior depending on the density of the population
C. Optimal Foraging Model
1. Optimal foraging model views foraging behavior as a compromise between benefits of nutrition and
costs of obtaining food
2. costs include energy expenditure and the risk of being eaten while foraging
3. Natural selection should favor foraging behavior that minimizes the costs and maximizes the benefits
a. The Northwestern crow
1) A crow will drop a whelk (mollusk) from a height to break its shell and feed on the soft parts
2) trade-off is between height from which whelk is dropped & number of times it must drop
3) Experiments showed total flight height (i.e. total energy expenditure) was least at 5 m
4) The average flight height for crows is 5.2 m
D. Balancing Risk and Reward
1. Risk of predation affects foraging behavior
a. Mule deer like to feed in open forested areas where they are less likely to be killed by mountain lions
E. Mating Behavior and Mate Choice
1. Mating behavior includes seeking or attracting mates, choosing a mate, and competing for mates
2. Mating behavior results from a type of natural selection called sexual selection
F. Mating Systems and Parental Care
1. The mating relationship between males and females varies greatly from species to species
2. Promiscuous mating- no strong pair-bonds or lasting relationships
3. Monogamous relationships, one male mates with one female
a. Males and females with monogamous mating systems have similar external morphologies
4. Polygamous relationships, an individual of one sex mates with several individuals of the other sex
a. Individuals usually sexually dimorphic: males and females have different external morphologies
b. Polygamous relationships can be either polygynous or polyandrous
c. Polygyny, one male mates with many females
• The males are usually more showy and larger than the females
d. Polyandry, one female mates with many males (very rare)
• The females are often more showy than the males
5. Parental Care- Needs of the young are an important factor constraining evolution of mating systems
a. Consider bird species where chicks need a continuous supply of food
• Male maximizes reproductive success by staying with mate, and caring for chicks
(monogamy)
b. Consider bird species where chicks are soon able to feed and care for themselves
• Male maximizes reproductive success by seeking additional mates (polygyny)
6. Certainty of paternity influences parental care and mating behavior
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a. Females can be certain that eggs laid or young born contain her genes; however, paternal
certainty depends on mating behavior
b. Paternal certainty low in species w/ internal fertilization- mating & birth are separated over time
c. Certainty is much higher when egg laying and mating occur together, as in external fertilization
• With external fertilization, parental care is at least as likely to be by males as by females
G. Sexual Selection and Mate Choice
1. Intersexual selection- members of one sex choose mates on the basis of certain traits
2. Intrasexual selection- competition between members of the same sex for mates
H. Mate Choice by Females
1. Female choice is a type of intersexual competition
a. Females drive sexual selection by choosing males with specific behaviors or features of anatomy
 female stalk-eyed flies choose males with long eyestalks
2. Mate choice in zebra finches
a. Female chicks who imprint on ornamented fathers are more likely to select ornamented mates
b. Suggest that mate choice by females has played a key role in the evolution of ornamentation in males
I. Male Competition for Mates
1. Male competition for mates is a source of intrasexual selection that can reduce variation among males
2. May involve agonistic behavior, an ritualized contest to determine which competitor gets a resource
J. Game Theory & Mate selection
1. In some species, sexual selection drives evolution of alternative mating behavior & male morphology
2. Fitness of a phenotype (behavior or morphology) depends on other phenotypes in the population
3. Game theory evaluates alternative strategies when the outcome depends on an individual’s strategy vs.
the strategy of his opponents
a. Ex. each side-blotched lizard has a blue, orange, or yellow throat
 each color has a specific strategy for obtaining mates
 throat color and mating strategy are genetic
c. As in a game, each strategy outcompetes one strategy, but may be outcompeted by another strategy
d. Success of one strategy depends on frequency of all strategies;- drives frequency dependent selection
VI. Inclusive fitness and altruistic social behavior
a. Natural selection favors behavior that maximizes an individual’s survival and reproduction
b. These behaviors are often selfish
1. Altruism- selflessness
a. Altruism- behavior that reduces individual reproductive fitness but increases the fitness of the group
• Ex. When predators are near, individual Belding’s ground squirrels gives alarm call to warn
others, even though this increases chances for caller to be killed
• Other species, (bees, naked mole rats) nonreproductive group members die protecting
reproductive queen and kings from predators
2. Inclusive Fitness- the cause of altruism
a. Inclusive fitness- total effect an individual has on passing on its genes by producing offspring and
helping close relatives produce offspring
3. Hamilton’s Rule and Kin Selection
a. William Hamilton- invented equation to predict when natural selection favors altruistim among
related individuals
b. Three key variables:
– Benefit to the recipient (B)
– Cost to the altruist (C)
– Coefficient of relatedness (the fraction of shared genes; r)
c. Hamilton’s rule- natural selection favors altruism when:
rB > C
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d. Kin selection- natural selection that favors altruistic behavior by enhancing reproductive success of
relatives
1) EX. warning behavior in Belding’s ground squirrels
• In a group, most of the females are closely related to each other
• Most alarm calls are given by females who are likely aiding close relatives
2) EX. Naked mole rats living within a colony are closely related
• Nonreproductive individuals increase their inclusive fitness by helping the reproductive
queen and kings (their close relatives) to pass their genes to the next generation
4. Reciprocal Altruism
a. Altruistic behavior to unrelated individuals can be adaptive if aided individual returns favor in future
b. Reciprocal altruism is limited to species with stable social groups where individuals meet repeatedly,
and cheaters (who don’t reciprocate) are punished
c. Reciprocal altruism has been used to explain altruism between unrelated individuals in humans
5. Social Learning
a. Social learning- learning by observing others: forms the roots of culture
b. Culture - system of information transfer by observation or teaching that influences behavior of
individuals in a population
c. Culture can alter behavior and influence the fitness of individuals
Case Study: Mate-Choice Copying
a. Mate-choice copying, individuals in a population copy the mate choice of others
b. EX. Poecilia reticulate (a type of guppy fish)
• Females mate with males attractive to other female guppies
• So, their sons are also more likely to be attractive to other females
Case Study: Social Learning of Alarm Calls
a. Vervet monkeys produce distinct alarm calls for different predators
b. Infant monkeys give undiscriminating calls but learn to fine-tune them by the time they are adults
6. Evolution and Human Culture
a. Sociobiology- a discipline that tries to relate human culture to evolutionary theory
b. Human behavior, like that of other species, results from interactions between genes and environment
• However, our social and cultural institutions may provide the only feature in which there is no
continuum between humans and other animals
Note to the wise: Go to text book & read up on Tinbergen, Lorenz, & Clark- they do ask about these three,
especially the first two!