ANIMAL BEHAVIOR
CAMPBELL & REECE
CHAPTER 51
ANIMAL BEHAVIOR
• a behavior is an action carried out by
muscles under control of the nervous
system in response to a stimulus
Behavior
• over time is subject to natural selection
• understanding any behavior requires
answering 4 ?s
1. What stimulus elicits the behavior, & what
physiological mechanisms mediate the response?
2. How does the animal’s experience during growth
& development influence the response?
3. How does the behavior aid survival &
reproduction?
4. What is the behavior’s evolutionary history?
Behavioral Ecology
• study of the ecological & evolutionary
basis for animal behavior
Fixed Action Patterns
• sequence of unlearned acts directly linked
to a simple stimulus
• are essentially unchangeable
• once started, they continue to completion
• sign stimulus: the trigger for the behavior
Migration
• a regular long-distance change in location
• animals use environmental stimuli to
provide cues to trigger behavior
• some animals track their position relative
to the Sun (even though Sun’s position
relative to Earth changes thru out the day)
Migration
• animals adjust to changes in Sun’s or stars
position by means of circadian clock
• some use magnetic fields (pigeons & some
fishes)
Behavioral Rhythms
• linked to seasons called: circannual
rhythms
– influenced by periods of daylight & darkness
in the environment
– birds exposed to artificial light simulating
longer daylight hrs will start to migrate
Behavioral Rhythms
• not all are linked to light/dark
– male fiddler crab waves large claw to attract
mates using signal of full or new moon
Animal Signals &
Communication
• a stimulus transmitted from 1 animal to
another is called a signal
• transmission & reception of signals
constitutes animal communication
Forms of Animal
Communication
• 4 common modes of animal
communication:
1. Visual
2. Chemical
3. Tactile
4. Auditory
Forms of Animal
Communication
• courtship behavior of Drosophila
melanogaster
– is a stimulus-response chain (response to
each stimulus is the stimulus for next
behavior
Symbolic Language
of the Honeybee
Pheromones
• chemical substances released by animals
that communicate thru odors or tastes
• common among mammals & insects
• often related to reproductive behavior
Pheromones as Alarm Signals
• in fish: if 1 injured  injured cells release
substance that increases vigilance of other
fish  school becomes more tightly
packed  move to lake or river bottom
where they are safer
Innate Behavior
• animal behavior that is developmentally
fixed & under strong genetic control
• it is exhibited in virtually same form in all
individuals in a population despite
internal & external environmental
differences during development & thru out
their lifetimes
Experience & Behavior
• How do researchers test the 2nd ?:
• How an animal’s experience during growth
& development influence the response to
stimuli?
Cross-Fostering Study
• young of 1 species placed under the care of
adults from another species
• these studies can be used to measure the
influence of social environment &
experience on behavior
Human Twin Studies
• compare behaviors of identical twins
raised apart with those raised in same
household
– studies have revealed nature & nuture both
contribute significantly
Learning
• modification of behavior based on specific
experiences
Imprinting
• formation at a specific stage in life of a
long-lasting behavioral response to a
specific individual or object
• distinguished from other types of learning
by having a sensitive period or critical
period: a limited developmental phase
when this type of learning can occur
Imprinting
• during the sensitive period:
– the young imprint on their parent & learn
basic behaviors of their species
– parents learn to recognize their offspring
Imprinting
• birds have no innate recognition of
“mother”
• they identify with the 1st object they
encounter that has certain key
characteristics (like any object that is
moving away from them)
Greylag Geese Imprinting of
Lorenz: 1933
Saving the Whooping Cranes
Spatial Learning
• establishment of a memory that reflects
the environment’s spatial structure
• studied digger wasps:
– Mother covers entrance with sand when leaves
nest..always comes right back to it
– hypothesized she locates her nest by learning
its position relative to local landmarks
Digger Wasp Study
Cognitive Map
• some animals guide their activity using a
cognitive map: a representation in the
nervous system of the spatial relationships
between objects in an animal’s
surroundings
• these animals can navigate more flexibly &
efficiently by relating landmark positions
to one another
Associative Learning
• ability to associate 1 environmental feature
(like color) with another (foul taste)
Associative Learning
• suited to lab studies because usually
involves classical conditioning or operant
conditioning
Classical Conditioning
• an arbitrary stimulus becomes associated
with a particular outcome
Operant Conditioning
• aka “trial-and –error”
learning
• animal learns to
associate one of its
behaviors with a
reward or
punishment & then
tends to repeat or
avoid that behavior
Associative Learning &
Evolution
• makes sense that some animals cannot
learn to make particular connections…
• associations animals make typically reflect
relationships likely to occur in nature
• associations that cannot be formed are
those unlikely to be of selective advantage
in a native environment
Cognition
• process of knowing that involves:
– awareness
– reasoning
– recollection
– judgement
Cognition
• has been thought that
only humans, higher
apes & marine
mammals
• but...some insects &
many other groups of
animals have
demonstrated some
levels of cognition in
lab experiments
Problem Solving
• the cognitive activity of devising a method
to proceed from 1 state to another in the
face of real or apparent obstacles
• varies with individual experience &
abilities
Development of Learned
Behaviors
• some birds learn their songs in stages
(during a sensitive period)
– young sparrow does not sing but memorizes
adult songs
– followed by a 2nd learning phase when juvenile
bird sings tentative notes called a subsong
– juvenile bird compares his subsong to adult
song..when he has it right the song
“crystallizes”…bird will only sing that song
rest of life
Social Learning
• modification of behavior thru observation
of other individuals
• young chimps learn to crack nuts by
watching their elders
• young vervet monkeys learn correct use of
alarm calls by (+) reinforcement from
elders
Social Learning
• forms the roots of culture (a system of
information transfer thru social learning
or teaching that influences the behavior of
individuals in a population)
• can change behavior and thereby influence
the fitness of individuals
Foraging Behavior
• food-obtaining behavior
• an optimal foraging model is based on the
idea that natural selection should favor the
foraging behavior that minimizes the costs
of foraging & maximizes the benefits
Mating Behavior & Mate
Choice
• mating behavior & mate choice play a
major role in determining reproductive
success
• includes:
– seeking or attracting mates
– choosing among potential mates
– competing for mates
– caring for offspring
Mating Systems
• vary with regard to both the length & # of
relationships
• Promiscuous: no strong pair-bonds
• Monogamous: mates remain together for
longer periods of time
• Polygamous: an individual of one sex
mating with several of the opposite sex
Sexual Dimorphism
• extent to which makes & females differ in
appearance
– typically varies with type of mating system
– monogamous: male & females alike
– polygamous: male much showier than females
Mating Systems & Parental
Care
• needs of the young greatly influences the
evolution of mating systems
• young birds require a large amount of
food: having a single mom would greatly
reduce survival chances…probably why
most birds are monogamous
Certainty of Paternity
• influences mating behavior & parental
care
• certainty of paternity generally low in most
species
– may explain why exclusively male parental
care is rare in mammals & birds
Certainty of Paternity
• is high when egg laying & mating occur at
same time
– external fertilization
• fishes: parental care just as likely to be male parent
as female parent
Certainty of Paternity
• does not mean that animals are aware of
those factors when they behave a certain
way…parental behavior correlates with
certainty of paternity because it has been
reinforced over generations by natural
selection
Sexual Selection
• influences the degree of sexual
dimorphism w/in a species
• intersexual selection: 1 sex choose mates
on basis of characteristics of other sex
– 1 with best song, or dance
• intrasexual selection: competition
between members of 1 sex for mates
Mate Choice by Females
• may play central role in evolution of male
behavior & anatomy thru intersexual
selection
Mate Choice Copying
• behavior in which individuals in a
population copy the mate choice of others
– female guppies prefer mates that are ass’c
with another female & they prefer male
guppies with more orange coloration
Male Competition for Mates
• may involve agonistic behavior: males
have a competition..winner gets the female
– does not seem to affect genetic variation
Game Theory
• evaluates alternative strategies in
situations where the outcome depends on
the strategies of all individuals involved
• provides a way to think about complex
evolutionary problems in which relative
performance (reproductive success
compared to other phenotypes), not
absolute performance is the key to
understanding evolution of behaviors.
Genetic Basis of Behavior
• studies in insects have revealed existence
of regulatory genes that control complex
behavior
Courtship Songs of Insects
• found to be under influence of multiple
genes as are other specific behaviors
– variations in these multiple genes brings
about variation in behavior
Voles Study: Closely Related
Species
• single gene variations can determine
differences in complex behaviors involved
in both mating & parenting
– increasing amt of vasopressin receptors in
males changed their mating & parenting
behaviors
Genetic Variation &
Evolution of Behavior
• significant differences can also be found
among members of same species
– coastal garter snakes will prey on banana
slugs & inland garter snakes will not a
genetically acquired taste
Genetic Variation in Western
Garter Snake
• turns out the inland western garter snake
cannot detect the odor of the banana slug
• hypothesis: 10,000 yrs ago when garter
snake 1st inhabited coastal area those who
could smell the plentiful banana slug
higher fitness so their #s increased in
coastal area
• inland where # of slugs much less, that
advantage gone
Variation in Migratory
Patterns
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•
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•
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Blackcap warbler:
1st migratory pattern: Germany  Africa
1950’s some Germany  Britain
behavior change rapid
researchers showed the different patterns
reflected a genetic variation
Altruism
• selflessness
• decreases an individual’s fitness but
increases the fitness of others in the
population
• explained by concept of inclusive fitness
Inclusive Fitness
• the total effect an individual has on
proliferating its genes by producing its
own offspring and by providing aid that
enables close relatives to produce
offspring
3 Key Variables in Act of
Altruism
1. Benefit to the Recipient
2. Cost to the Altruist
3. Coefficient of Relatedness (r) = fraction of
shared genes
• natural selection will favor altruism when
(benefit to recipient) x (r) > (cost to
altruist) = Hamilton’s Rule
• altruistic behavior toward unrelated
individuals can be adaptive if the aided
individual returns the favor in the future
• exchange of favors called reciprical
altruism
Sociobiology
• study of how human nature is related to
evolutionary behavior
• premise: certain behavioral characteristics
exist because they are expressions of genes
that have perpetuated by natural selection
• Debate that is ongoing