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CHAPTER 55
BEHAVIORALECOLOGY
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Behavior is the observable response of organismsto internal or external stimuli
Behavioral ecology studies how behaviorcontributes to the differential survival andreproduction of organisms
Ethology focused on the physiologicalmechanisms of behavior Proximate causes – change in day length -cause deer
rut
Behavioral ecologists focus on the adaptivesignificance of a behavior Ultimate causes – effect on reproductive success and
survival
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Impact of genetics and learning on behavior
Fixed action patterns F!P" Innate or genetically programmed behavior
#ommonly called instinctual
$nce initiated% will continue until completedEgg-rolling response in geese Improves fitness because it increases survival of young&ign stimulus – initiates behavior
Egg out of nest 'ale stic(lebac(s attac( red ventral surface while ignoring
realistic fish model lac(ing red underside
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Fig) **)+
Fig) **),
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earning – modify behavior based on
previous behavior
.abituation – simplest form of learning$rganism ignores repeated stimulus
Form of nonassociative learning – decrease in
response to stimulus due to repetition
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!ssociative learning - association develops betweenstimulus and response
Behavior is changed or conditioned throughout the association , main types
+) #lassical conditioning – involuntary response becomesassociated positively or negatively with a stimulus that did notoriginally elicit the response Pavlov/s dog salivates when the bell rings Food is the unconditioned stimulus Bell is the conditioned stimulus &alivation in response to food is the unconditioned response &alivation in response to the bell is conditioned response
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,) $perant conditioning – animal/s behavior
reinforced by a conse0uence reward or
punishment" &(inner box where rat bumps into a lever and
gets food
!ssociate lever with food
!lso called trial-and-error learning
Birds will learn to avoid bad tasting butterflies
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Fig) **)1
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#ognitive learning – ability to solve problems
with conscious thought and without direct
environmental feedbac( #himpan2ees stac( boxes to reach banana
3avens retrieve meat by pulling up a string http455www)chonday)com56ideos5crowintelige,
Fig) **)7
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Behavior is often a mix of innate and learned Birds are genetically programmed to learn but they
will sing the correct song only if the correct songs areheard
Fig) **)*
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#ritical period – time when many animals develop species-
specific patterns of behavior
Imprinting – goslings follow the first moving thing as 8mother9human% watering can% blac( box" Innate behavior is the ability to imprint
Factors in the environment are the stimulus to which imprinting is directed
'igration – experienced
birds can correct for
displacement
complex navigational s(ill"
while young% inexperienced
birds cannot correct
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ocal and long-range migration
ocal movements'ovements to find food% water% nesting site
:inesis – movement in response to stimulus but notdirected toward or away from source ;axis – more directed movement
Positive phototaxis – toward light <egative phototaxis – away from light
$ther examples include sea turtle hatchlings% and positiverheotaxis in fish
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'igration – long-
range seasonal
movement generally
lin(ed to seasonal
availability of food
Bird% mammal% andinsect examples
1 mechanisms to
find their way
!rctic terns4 ,7%=>>
miles migrated yearlyFig) **)=
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+) Piloting – animal moves from one familiarlandmar( to the next Features of the coastline% for example
,) $rientation – ability to follow compass bearingand travel in straight line – cannot ad?ust forcourse
1) <avigation – follow compass bearings but alsoset or ad?ust path !dult starlings can ad?ust flight path when
transported and released ?uveniles cannot"
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Fig) **)@
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'any species use a combination of navigational
reference points and an internal cloc(Pigeons integrate internal cloc( with position of the sun –
for every hour their internal cloc(s were shifted% their
orientation shifted +*A
<ot all migrations well understoodreen sea turtles migrate to !scension Island to lay eggs
.oming pigeons can be transported to sites they have
never been to and fly directly home
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Foraging
$ptimality theory predicts an animalshould behave in a way that maximi2es
benefits of a behavior minus its costs $ptimal foraging proposes that an animal
see(s to obtain the most energy possiblewith the least expenditure of energy;he more net energy gained% the greater the
reproductive success
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&hore crabs will eat
different si2edmussels Prefer intermediate
mussels with highest
rate of energy return arger mussels yield
more energy but ta(e
longer to open
&maller mussels areeasier to open but
yield less energyFig) **)+>
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Cefending a territory has costs andbenefits
;erritory – fixed area in which individual orgroup excludes others
$ptimi2e territory si2e based on costs andbenefits Benefit is exclusive access to resource- food%
mates% nesting sites #ostly to defend
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olden-winged
sunbird &aved D=> calories
a day in reduced
foraging activity &pent D,= calories
in defending the
territory <et gain of *,
calories a day
Fig) **)++
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#heetahs need
large territoriesrelative to body si2e
to hunt successfully
annet territorysi2e determined by
how far bird can
reach to pec( its
neighbor withoutleaving nest
Fig) **)++
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#ommunication
Use of specifically designed signals or
displays to modify the behavior of others
#hemical
!uditory
6isual
;actile
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#hemical communication#ommon among canines and felines¢ trails laid by social insectsPheromones produced by female moths to attract
malesueen bee releases pheromones to suppress
reproductive system of wor(ers !uditory communication&ounds travel farther in air at dawn and dus( because
it is less turbulent
'any males use auditory communication to attractfemales
&ound production can also lure predators
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6isual communication#ompetition among males for most impressive
displays leads to elaborate coloration andextensive ornamentation
'ale fireflies flash species specific number andduration of flashes
Predator uses flashes to lure males in to eat them
;actile communicationUsed to establish bonds between group members
3ound dance or waggle dance of honeybee scoutconveys food location
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Fig) **)+,
Fig) **)+1
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iving in groups
'uch of animal behavior directed at other
animals
&ome of the more complex behavioroccurs in groups li(e floc(s or herds
roup living can reduce predation through Increased vigilance
Protection in numbers
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Increased vigilance'any eyes hypothesis – by living in groups%
individuals may decrease the amount of timescanning for predators and increase timefeeding
If each pigeon occasionally loo(s up to scan
for a haw(% the bigger the group% the moreli(ely that one bird will spot a haw( earlyenough for the floc( to ta(e flight
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Fig) **)+7
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Protection in numbers;ypically% predators ta(e one prey item per attac( In a large group% chances of being that prey item are
reduced8&elfish herd9 – each individual can minimi2e the
danger to itself by choosing the location that isclosest to the center of the group
roup si2e may be the result of trade offs betweenthe benefits of group living and costs li(e groomingand altruism
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!ltruism
Behavior that appears to benefit others at
a cost to oneself
'ost altruistic acts serve to benefit theindividual/s close relatives
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Individual selfish behavior is more li(elyroup selection – group containing altruists would
have a survival advantage over group composed ofselfish individuals
Individual selection more li(ely because 'utant individuals that use resources have an
advantage over those that conserve resources &elfish individuals can immigrate from other areas
For group selection to wor(% groups must die faster than
others – individuals die more often than groups
roup selection assumes that individuals can predictfood availability to conserve resources as needed – little
evidence that they can
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Example of selfish behavior 'ale .anuman langurs (ill infants when they ta(e
over groups of females from other malesGhen not nursing% females become sexually receptive
sooner% so a male can father offspring sooner
Infanticide ensures that the male will father more
offspringenes governing this trait spread by natural selection
Fig) **)+*
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:in selection#oefficient of relatedness – probability that any ,
individuals will share a copy of a particular gene is a0uantity r
!n organism can not only pass on its genes by having
offspring but also by ensuring that relatives survive
Inclusive fitness designates the total number of copiesof genes passed on through one/s relatives or as
one/s own offspring
:in selection – behavior that lowers an individual/s
own fitness but enhances the reproductive success ofrelatives
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Fig) **)+H
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.amilton/s rule !ltruistic gene favored by natural selection
when
r is the coefficient of relatedness of donoraltruist" to recipient
B is benefit to recipient# is cost incurred by donor
rB#
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Datana caterpillarsexample Brightly colored and
assume specific posewhen threatened
Predator has to eat
one to learn to avoidthem Ceath of individual in
group of relatedcaterpillars benefits
siblings r J>)*% BJ*>% and
#J+% then,*>)*x*>"+ sogenes will spread
Fig) **)+D
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!ltruism in social insects due to genetics and
lifestyle'ost extreme form of altruism is sterile castes in
social insects Eusociality – wor(ers females" help 0ueen raise
offspring
.aplodiploidy – females are diploid% males are haploid%
females are more related to their sisters >)D*" than they
would be to their own offspring >)*"
Existence of eusocial mammals predicted based
on lifestyle <a(ed mole rats have a 0ueen who suppresses
reproduction in other females
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Fig) **)+=
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Fig) **)+@
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3eciprocal altruism
#ost to the altruistoffset by li(elihood
of a return benefit
Female vampire
bats will share food Unrelated females
are more li(ely to
share food with
those that hadrecently shared with
them
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'ating systems
<atural selection favors production of the rarer
sex so that the sex ratio is (ept balanced at +4+
'onogamy – each individual mates exclusivelywith one partner
Polygamy – individuals mate with more than one
partner Polygyny – one male mates with many females
Polyandry – one female mates with many males
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&exual selection
Promotes traits that will increase anorganismKs mating success, forms
Intersexual – member of one sex chooses matebased on particular characteristics
Intrasexual – members of one sex compete overpartners with the winner performing most of thematings
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Female mate choice
Female hangingfliesdemand a nuptial gift –allows female to producemore eggs and allowsmale to copulate longer
Female stic(lebac(s
prefer males that sha(emore during courtship asevidence that he will be abetter parent
#hoices based onplumage color orcourtship displays –widowbird withexperimentallylengthened tails attractedmore females andfathered more clutches
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'ate competition between individuals In many species% females do not actively
choose between mates Instead they mate with competitively superior
malesCominance determined by fighting or
rituali2ed sparring'ale-male competition produces males
substantially larger than females&mall males can still father offspring by
intercepting females
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'onogamy$ne male mates with one female'ales and females generally similar in body si2e and
appearance'ate-guarding hypothesis – males stay with a female
to protect her from being fertili2ed by other males'ale assistance hypothesis – males remain with
females to help them rear offspring – he would havefew surviving offspring if he did not
Female-enforced monogamy hypothesis– femaleinterferes with male attracting other females
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Polygyny$ne male mates with more than one female
Females mate with only one male
!ssociated with uniparental care of young
'ales contribute little to raising young
&exual dimorphism typical
;ypes 3esource based polygyny – patchy distribution of resource
and female visits for resource
.arem mating structure – females naturally congregate and
male controls area #ommunal courting – males display in le(% females mate
after males display
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Fig) **),7
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Polyandry$ne female mates with several males
3arer Female is larger of the sexes Female spotted sandpiper reproductive success
limited only by the number of males she can find toincubate her eggs
'ale pipefish have brood pouches and femaleproduces enough eggs for , male brood pouches ifshe can find another male
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Fig) **),1