Transcript Chapter 51: Animal Behavior

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Chapter 51:
Animal
Behavior
Mrs. Valdes
AP Biology
+Overview: Shall We Dance?
 Cranes: interesting
dancing behavior during
courtship
 Animal behavior based on physiological systems
and processes
 Behavior: nervous system’s response to stimulus;
carried out by muscular or hormonal system
 Behavior helps animal
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Obtain food
Find partner for sexual
reproduction
Maintain homeostasis
 Behavior
subject
to natural selection
Concept 51.1: Discrete sensory inputs can
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stimulate both simple and complex behaviors
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Animal’s behavior = response to external and internal stimuli
Ethology: scientific study of animal behavior, particularly in natural
environments
According to early ethologist Niko Tinbergen, four questions should be asked
about behavior:
1.
What stimulus elicits behavior, and what physiological mechanisms
mediate response?
3.
How does animal’s experience during growth
and development influence response
mechanisms?
4.
How does behavior aid survival and
reproduction?
5.
What is behavior’s evolutionary history?
Proximate causation: “how” explanations, focus on
 Environmental stimuli that trigger behavior
 Genetic, physiological, and anatomical mechanisms underlying behavior
Ultimate causation: “why” explanations, focus on evolutionary significance of
behavior
Behavioral ecology: study of ecological and evolutionary basis for animal
behavior; integrates proximate and ultimate explanations for animal behavior
Fixed Action Patterns
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 DEFINE: sequence of
unlearned, innate
behaviors that is
unchangeable
 Once
initiated
carried to completion
 triggered by external
cue known as sign
stimulus
 Ex:
fish
male stickleback
 Stimulus
for attack
behavior: red
underside of intruder
 Action: presented with
unrealistic models, as
long as some red is
present, attack
behavior occurs
+Oriented Movement
Environmental cues can trigger movement in a particular direction
 Kinesis: simple change in activity or turning rate in response to a
stimulus
 Ex: sow bugs become more active in dry areas and less active in
humid areas
 Sow bug behavior varies with humidity, sow bugs do NOT move
toward or away from specific moisture levels
 Taxis: more or less automatic, oriented movement toward or away
from a stimulus
 Ex: stream fish exhibit positive taxis and automatically swim in
upstream direction
 prevents them from being swept away and keeps them facing
direction from which food will come
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+ Migration
 DEFINE: regular, long-distance
change in
location
 Animals
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can orient themselves using
position of sun and their circadian clock
position of North Star
Earth’s magnetic field
+ Behavioral Rhythms
 Some
animal behavior affected by animal’s
circadian rhythm
 Behaviors such as migration and reproduction are
linked to changing seasons, or a circannual
rhythm
 Some behaviors linked to lunar cycles
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Ex: courtship in fiddler crabs occurs during new and full moon
+ Animal Signals and Communication
 Signal:
behavior that causes
change in another animal’s
behavior
 Communication: transmission
and reception of signals
 Animals communicate using
visual, chemical, tactile, and
auditory signals
 Type of signal closely related to
lifestyle and environment
 Honeybees show complex
communication with symbolic
language
 bee returning from field
performs dance to
communicate information
about position of food source
+Pheromones
 Pheromones: chemicals
emitted through
odors
 effective
at very low concentrations
 Ex: minnow
or catfish
injured alarm
substance in fish’s skin
disperses in water
induce fright response
among fish in area
Concept 51.2: Learning establishes specific links
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between experience and behavior
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Innate behavior: developmentally fixed; under strong
genetic influence
Learning: modification of behavior based on specific
experiences
Habituation: simple form of learning; involves loss of
responsiveness to stimuli that convey little or no
information
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Ex:, birds stop responding to alarm calls from their species if not followed by actual attack
Imprinting: behavior that includes learning and innate
components; generally irreversible
 distinguished from other learning by sensitive period
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limited developmental phase that is ONLY TIME when
certain behaviors can be learned
Ex: young geese following their mother
 Konrad Lorenz showed when baby geese spent first
few hours of life with him imprinted on him as
parent
Conservation biologists taken advantage of imprinting in
programs to save whooping crane from extinction
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Young whooping cranes imprint on humans in “crane
suits” who lead crane migrations using ultralight aircraft
+ Spatial Learning
 Spatial
learning: more
complex modification of
behavior based on
experience with spatial
structure of environment
 Niko Tinbergen
showed
how digger wasps use
landmarks to find nest
entrances
 Cognitive
map: internal
representation of spatial
relationships between
objects in animal’s
surroundings
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Ex: Clark’s nutcrackers can
find food hidden in caches
located halfway between
particular landmarks
+ Associative Learning
 DEFINE: animals
another
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associate one feature of environment with
Ex: white-footed mouse avoid eating caterpillars with specific colors
after bad experience with distasteful monarch butterfly caterpillar
 Classical
conditioning: type of associative learning in
which arbitrary stimulus associated with reward or
punishment
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Ex: dog repeatedly hears bell before being fed  salivate in
anticipation at bell’s sound
 Operant
conditioning: type of associative learning in
which animal learns to associate one of its behaviors with a
reward or punishment
 also called trial-and-error learning
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Ex: rat that fed after pushing lever will
learn to push lever in order to receive food
Ex: predator learn to avoid specific type
of prey associated with painful experience
+ Cognition and Problem Solving
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Cognition: process of knowing that includes awareness, reasoning,
recollection, and judgment
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Problem solving: process of devising strategy to overcome obstacle
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Ex: honeybees can distinguish “same” from “different”
Ex: chimpanzees stack boxes in order to reach suspended food
Some animals learn to solve problems by observing other individuals
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Ex: young chimpanzees learn to crack palm nuts with stones by copying
older chimpanzees
Fig. 51-UN1
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Imprinting
Learning and
problem solving
Cognition
Associative learning
Spatial learning
Social learning
Concept 51.3: Both genetic makeup and environment
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contribute to the development of behaviors
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Animal behavior governed by complex interactions between genetic and
environmental factors
Cross-fostering studies help behavioral ecologists identify contribution
of environment to animal’s behavior
Cross-fostering study: places young from one species in care of adults
from another species
 California mice and white-footed mice study uncovered influence of social
environment on aggressive and parental behaviors
 Cross-fostered mice developed some behaviors that were consistent
with their foster parents
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Humans: twin studies allow researchers to compare relative influences of
genetics and environment on behavior
+Regulatory Genes and Behavior
 Master
regulatory gene
can control many
behaviors
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Ex: single gene controls many
behaviors of male fruit fly
courtship ritual
 Multiple
independent
genes can contribute to
a single behavior
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Ex: Green lacewings: courtship
song unique to each species;
multiple independent genes
govern different components of
courtship song
Genetically Based Behavioral
+Variation in Natural Populations
 Behavioral
variation within species
corresponds to environmental variation
evidence of past evolution
 Example: Most blackcaps (birds) that
breed in Germany winter in Africa, but
some winter in Britain
 two migratory populations are genetically
distinct
 Example: Natural diet of western garter
snakes varies by population
 Coastal populations feed mostly on
banana slugs, while inland populations
rarely eat banana slugs
 Studies show differences in diet are
genetic
 two populations differ in ability to detect
and respond to specific odor molecules
produced by banana slugs!
+ Influence of Single-Locus Variation
 Differences
at single locus can sometimes
have a large effect on behavior
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Ex: male prairie voles pair-bond with their mates, while male
meadow voles do not
 level of specific receptor for neurotransmitter determines which
behavioral pattern develops
Concept 51.4: Selection for individual survival and
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reproductive success can explain most behaviors
Genetic components of behavior evolve through NATURAL
SELECTION!!!!!
 Behavior can affect fitness by influencing foraging and mate choice
 Natural selection refines behaviors that enhance efficiency of feeding
 Foraging: food-obtaining behavior; includes recognizing, searching
for, capturing, and eating food items
 Drosophila melanogaster, variation in gene dictates foraging behavior in
larvae
 Larvae with one allele travel
farther while foraging than
larvae with other allele
 Larvae in high-density
populations benefit from
foraging farther for food
 Larvae in low-density
populations benefit from
short-distance foraging
 Natural selection favors different
foraging behavior depending
density of the population
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Optimal Foraging Model
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 Optimal
foraging model: views foraging behavior as
compromise between benefits of nutrition and costs of
obtaining food
 costs of obtaining food include energy expenditure and
risk of being eaten while foraging
 Natural selection should favor foraging behavior that minimizes
costs and maximizes benefits
 Optimal foraging behavior demonstrated by Northwestern crow
 crow will drop whelk (a mollusc) from height
to break shell and feed on soft parts
 crow faces trade-off between height from
which it drops whelk and number of times
it must drop whelk
 Researchers determined experimentally that
total flight height (which reflects total energy
expenditure) minimized at drop height of 5 m
AND…
 average flight height for crows is 5.2 m.
BOOM. SCIENCE.
Average number of drops
50
100
40
Average number of drops
30
75
Total flight height
20
Drop height
preferred
by crows = 5.23 m
10
50
25
0
2
3
5
7
Drop height (m)
15
Total flight height (number of drops
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125
60
drop height in m)
Fig. 51-19
+ Mating Behavior and Mate Choice
Mating behavior includes seeking or attracting
mates, choosing among potential mates, and
competing for mates
 Mating behavior results from type of natural
selection called sexual selection
 Promiscuous: no strong pair-bonds or lasting
relationships; many animals
 Monogamous relationships: one male mates with
one female
 Males and females with monogamous mating
systems have similar external morphologies
 Polygamous relationships: individual of one sex
mates with several individuals of other sex; species
usually sexually dimorphic: males and females have
different external morphologies
 Polygyny: one male mates with many females
 Males usually more showy and larger than
females
 Polyandry: one female mates with many males;
RARE
 Females often more showy than males
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 Needs of young important factor constraining evolution
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of mating systems
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Ex: Bird species chicks need continuous supply of food
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A male maximizes his reproductive success by staying with
his mate, and caring for his chicks (monogamy)
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Ex: Bird species chicks soon able to feed and care for self
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A male maximizes his reproductive success by seeking additional
mates (polygyny)
 Females
certain eggs laid / young born contain her genes;
however, paternal certainty depends on mating behavior
 Paternity certainty influences parental care and mating
behavior
 Paternal certainty relatively low species with internal
fertilization
 mating and birth separated over time
 Paternal certainty much higher when egg
laying and mating occur together, as in
external fertilization
 parental care is at least as likely to be by
males as by females
Sexual Selection and Mate Choice
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 Intersexual selection: members of one sex
choose mates on basis of certain traits
 Female Choice
 Intrasexual selection: involves
competition between members of same sex
for mates
Mate Choice by Females
 Females drive sexual selection by choosing
males with specific behaviors or features of
anatomy
 Ex: female stalk-eyed flies choose males
with relatively long eyestalks
 Ornaments, such as long eyestalks, often
correlate with health and vitality
 Ex: Female zebra finch chicks who imprint
on ornamented fathers are more likely to
select ornamented mates
 Experiments suggest mate choice by
female zebra finches play key role in
evolution of ornamentation in male zebra
finches
Fig. 51-24
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Experimental Groups of Parental Pairs
Both parents
ornamented
Males
ornamented
Offspring
Control Group
Females
ornamented
Parents not
ornamented
Offspring
Mate preference of female offspring: Mate preference of female offspring:
ornamented male
none
Male Competition
+for Mates
 source of intrasexual
selection that can
reduce variation
among males
 may involve
agonistic behavior
 often
ritualized
contest that
determines which
competitor gains
access to resource
(lady or land that
lady likes)
+ Applying Game Theory
 Sexual
selection driven evolution of alternative mating
behavior and morphology in males
 Fitness of particular phenotype (behavior or morphology)
depends on phenotypes of other individuals in population
 Game theory: evaluates alternative strategies where outcome
depends on each individual’s strategy and strategy of other
individuals
 Ex: each side-blotched lizard has blue, orange, or yellow throat
 each color associated with specific strategy for obtaining mates
 genetic basis to throat color and mating strategy
 Like rock-paper-scissors, each strategy
will outcompete one strategy, but be
outcompeted by other strategy
 THUS! success of each strategy
depends on frequency of all of
strategies;
 THIS drives frequency-dependent
selection
Concept 51.5: Inclusive fitness can account for the
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evolution of altruistic social behavior
 Natural
selection favors behavior that
maximizes individual’s survival and
reproduction
 These behaviors are often selfish
Altruism:
 Occasionally some animals behave in ways
that reduce their individual fitness but
increase fitness of others AKA selflessness
 Ex: under threat from predator, individual
Belding’s ground squirrel make alarm call to
warn others, even though calling increases
chances that caller is killed
 Ex: naked mole rat populations,
nonreproductive individuals sacrifice
lives protecting their reproductive
queen and kings from predators
+ Inclusive Fitness
 Altruism
explained by inclusive fitness
 Inclusive
fitness: total effect individual has
on proliferating its genes by producing
offspring and helping close relatives produce
offspring
Hamilton’s
Rule and Kin Selection
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 William Hamilton proposed quantitative measure for predicting
when natural selection would favor altruistic acts among related
individuals
 Three key variables in altruistic act:
 Benefit to recipient (B)
 Cost to altruist (C)
 Coefficient of relatedness
(fraction of genes that, on average,
are shared; r)
 Natural selection favors altruism when:
rB > C
 Hamilton’s rule: this inequality
 Kin selection: natural selection that favors this kind of altruistic
behavior by enhancing reproductive success of relatives
 Ex: warning behavior in Belding’s ground squirrels
 In group, most of females closely related to each other
 Most alarm calls given by females who aiding close relatives
 Ex: Naked mole rats living within colony are closely related
 Nonreproductive individuals increase their inclusive fitness by
helping reproductive queen and kings (their close relatives) to
pass their genes to the next generation
Fig. 51-29
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Mean distance (m)
moved from
birthplace
300
Male
200
100
Female
0
1
2
3
4
12 13 14
Age (months)
15
25
26
+Reciprocal Altruism
 Reciprocal
altruism: altruistic behavior toward
unrelated individuals can be adaptive if aided
individual returns favor in future
 limited
to species with stable social groups where
individuals meet repeatedly, and cheaters (who don’t
reciprocate) are punished
 used to explain altruism between unrelated individuals
in humans
+ Social Learning
 DEFINE: learning
through observation of others and forms
roots of culture
 Culture: system of information transfer through
observation or teaching that influences behavior of
individuals in population
 can alter behavior and influence
fitness of individuals
 Mate-choice copying: individuals
in population copy mate choice of
others
 This type of behavior extensively
studied in guppy Poecilia reticulata
 Females who mate with males
attractive to other females more
likely to have sons that are
attractive to other females
 “Sexy Son” Hypothesis
+ Evolution and Human Culture
 No
other species comes close to
matching social learning and
cultural transmission that occurs
among humans
 Human
culture related to
evolutionary theory in distinct
discipline of sociobiology
 Human
behavior results from
interactions between genes and
environment
 However, social
and cultural
institutions may provide ONLY
feature in which there is NO
continuum between humans and
other animals
+You should now be able to:
1.
State Tinbergen’s four questions and identify each as a proximate or ultimate
causation
2.
Distinguish between the following pairs of terms: kinesis and taxis, circadian and
circannual behavioral rhythms, landmarks and cognitive maps, classical and operant
conditioning
3.
Suggest a proximate and an ultimate cause for imprinting in newly hatched geese
4.
Explain how associative learning may help a predator avoid toxic prey
5.
Describe how cross-fostering experiments help identify the relative importance of
environmental and genetic factors in determining specific behaviors
6.
Describe optimal foraging theory
7.
Define and distinguish among promiscuous, monogamous, and polygamous mating systems
8.
Describe how the certainty of paternity may influence the development of mating systems
9.
Distinguish between intersexual and intrasexual selection
10.
Explain how game theory may be used to evaluate alternative behavioral strategies
11.
Define altruistic behavior and relate the coefficient of relatedness to the concept of altruism
12.
Distinguish between kin selection and reciprocal altruism
13.
Define social learning and culture