chapter 55 behavioral ecology

7/17/2019 Chapter 55 Behavioral Ecology

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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&cent 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



Fig) **),1

chapter 55 behavioral ecology

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