Transcript chapter 55 behavioral ecology

CHAPTER 55
BEHAVIORAL
ECOLOGY
Prepared by
Brenda Leady, University of Toledo
Copyright (c) The McGraw-Hill
Companies, Inc. Permission required
for reproduction or display.
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Behavior is the observable response of
organisms to internal or external stimuli
 Behavioral ecology studies how behavior
contributes to the differential survival and
reproduction of organisms
 Ethology focused on the physiological
mechanisms of behavior
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 Proximate
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causes – change in day length
Behavioral ecologists focus on the
adaptive significance of a behavior
 Ultimate
causes – effect on reproductive
success
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Some Behavior Results from Simple
Genetic Influences
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W.C. Rothenbuhler’s 1964 work showed a genetic basis to
behavior in honeybees
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Jennifer Brown in 1996 found fosB gene for nurturing in
mice
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Hygienic bees removed diseased larvae using 2 distinct maneuvers
– uncapping cells and removing larvae
Strains that were not hygienic did not do this
u – uncapping, U – did not uncap
r – larval removal, R – no removal
uurr – hygienic, UURR – not hygienic
UuRr – not hygienic, uuRr – uncap cells but larva not removed, Uurr
– remove larva if cells uncapped
Normal mice clean pups, nurse them, crouch over them
Mutant mice lacking fosB do not do these behaviors and pups die
Single gene can have dramatic impact on behavior
Impact of genetics and learning on behavior

Fixed action patterns (FAP)
 Innate
or genetically programmed behavior
 Once initiated, will continue until completed
 Egg-rolling response in geese
 Improves fitness because it increases survival
of young
 Sign stimulus – initiates behavior
Egg out of nest
 Male sticklebacks attack red ventral surface while
ignoring realistic fish model lacking red underside
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Learning – modify behavior based on
previous behavior
 Habituation – simplest form of learning
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 Organism
ignores repeated stimulus
 Form of nonassociative learning – decrease in
response to stimulus due to repetition
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Associative learning - association
develops between stimulus and response
2 main types
1.
Classical conditioning – involuntary response
becomes associated positively or negatively
with a stimulus that did not originally elicit
the response
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Pavlov’s dog salivates when the bell rings
Food is the unconditioned stimulus
Bell is the conditioned stimulus
Salivation in response to food is the
unconditioned response
Salivation in response to the bell is conditioned
response
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2.
Operant conditioning – animal’s behavior
reinforced by a consequence (reward or
punishment)

Skinner box where rat bumps into a lever
and gets food
 Associate lever with food
 Also called trial-and-error learning
 Birds will learn to avoid bad tasting
butterflies
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(a) Blue Jay eating monarch
(b) Blue Jay vomiting
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Cognitive learning – ability to solve problems
with conscious thought and without direct
environmental feedback
 Chimpanzees
stack boxes to reach banana
 Ravens retrieve meat by pulling up a string
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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 are
heard
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Critical period – time when many animals
develop species-specific patterns of
behavior
– goslings follow the first moving
thing as “mother”
 Imprinting
Innate behavior is the ability to imprint
 Factors in the environment are the stimulus to
which imprinting is directed
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– experienced birds can correct for
displacement (complex navigational skill)
while young, inexperienced birds cannot
correct
 Migration
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Local and long-range migration
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Local movements
 Movements
to find food, water, nesting site
 Kinesis – movement in response to stimulus
but not directed toward or away from source
 Taxis – more directed movement
Positive phototaxis – toward light
 Negative phototaxis – away from light
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Tinbergen’s Experiments Show Digger Wasps Use
Landmarks to Find Their Nests
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Digger wasp females provide honeybees for
larvae to feed on
Each larva needs 5 to 6 bees which must be
brought individually to nest
Tinbergen hypothesized wasps found nest by
creating mental map of area
First, experimentally adjusted landmarks
 Wasps
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flew to moved pinecones
Second, tested if it was sight or smell of
pinecones
 Found
it was sight of cones used as map
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Migration – longrange seasonal
movement
generally linked
to seasonal
availability of food

Bird, mammal,
and insect
examples
 3 mechanisms to
find their way
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1.
Piloting – animal moves from one familiar
landmark to the next
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2.
3.
Features of the coastline, for example
Orientation – ability to follow compass
bearing and travel in straight line –
cannot adjust for course
Navigation – follow compass bearings but
also set or adjust path
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Adult starlings can adjust flight path when
transported and released (juveniles cannot)
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Many species use a combination of
navigational reference points and an
internal clock
 Pigeons
integrate internal clock with position
of the sun – for every hour their internal
clocks were shifted, their orientation shifted
15°
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Not all migrations well understood
 Green
sea turtles migrate to Ascension Island
to lay eggs
 Homing pigeons can be transported to sites
they have never been to and fly directly home
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Foraging
Optimality theory predicts an animal
should behave in a way that maximizes
benefits of a behavior minus its costs
 Optimal foraging proposes that an animal
seeks to obtain the most energy possible
with the least expenditure of energy
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 The
more net energy gained, the greater the
reproductive success
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Shore crabs will eat
different sized
mussels
 Prefer
intermediate
mussels with highest
rate of energy return
 Larger mussels yield
more energy but take
longer to open
 Smaller mussels are
easier to open but
yield less energy
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Defending a territory has costs and
benefits
– fixed area in which individual or
group excludes others
 Optimize territory size based on costs and
benefits
 Territory
Benefit is exclusive access to resource- food,
mates, nesting sites
 Costly to defend
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Golden-winged
sunbird
 Saved 780 calories
a day in reduced
foraging activity
 Spent 728 calories
in defending the
territory
 Net gain of 52
calories a day
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Cheetahs need
large territories
relative to body
size to hunt
successfully
 Gannet territory
size determined by
how far bird can
reach to peck its
neighbor without
leaving nest
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Communication
Use of specifically designed signals or
displays to modify the behavior of others
 Chemical
 Auditory
 Visual
 Tactile
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Chemical communication
 Common
among canines and felines
 Scent trails laid by social insects
 Pheromones produced by female moths to
attract males
 Queen bee releases pheromones to suppress
reproductive system of workers
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Auditory communication
 Sounds
travel farther in air
 Air at dawn and dusk less turbulent
 Many males use auditory communication to
attract females
 Sound production can also lure predators
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Visual communication
 Competition
among males for most
impressive displays leads to elaborate
coloration and extensive ornamentation
 Male fireflies flash species specific number
and duration of flashes
 Predator uses flashes to lure males in to eat
them
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Tactile communication
 Used
to establish bonds between group
members
 Round dance or waggle dance of honeybee
scout conveys food location
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Living in groups
Much of animal behavior directed at other
animals
 Some of the more complex behavior
occurs in groups like flocks or herds
 Group living can reduce predation through
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 Increased
vigilance
 Protection in numbers
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Increased vigilance
eyes hypothesis – by living in groups,
individuals may decrease the amount of time
scanning for predators and increase time
feeding
 If each pigeon occasionally looks up to scan
for a hawk, the bigger the group, the more
likely that one bird will spot a hawk early
enough for the flock to take flight
 Many
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Protection in numbers
 Typically,
predators take one prey item per
attack
 In a large group, chances of being that prey
item are reduced
 “Selfish herd” – each individual can minimize
the danger to itself by choosing the location
that is closest to the center of the group
 Group size may be the result of trade offs
between the benefits of group living and costs
like grooming and altruism
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Altruism
Behavior that appears to benefit others at
a cost to oneself
 Most altruistic acts serve to benefit the
individual’s close relatives
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Individual selfish behavior is more likely
selection – group containing altruists
would have a survival advantage over group
composed of selfish individuals
 Individual selection more likely because…
 Group
Mutant individuals that use resources have an
advantage over those that conserve resources
 Selfish individuals can immigrate from other areas
 For group selection to work, groups must die faster
than others – individuals die more often than groups
 Group selection assumes that individuals can predict
food availability to conserve resources as needed –
little evidence that they can
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Example of selfish behavior
 Male
Hanuman langurs kill infants when they take
over groups of females from other males
 When not nursing, females become sexually
receptive sooner, so a male can father offspring
sooner
 Infanticide ensures that the male will father more
offspring
 Genes governing this trait spread by natural selection
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
Kin selection
of relatedness – probability that
any 2 individuals will share a copy of a
particular gene is a quantity r
 An 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 copies of genes passed on through one’s
relatives or as one’s own offspring
 Kin selection – behavior that lowers an
individual’s own fitness but enhances the
reproductive success of relatives
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 Coefficient
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Hamilton’s rule
 Altruistic
gene favored by natural selection
when
rB>C
r
is the coefficient of relatedness of donor
(altruist) to recipient
 B is benefit to recipient
 C is cost incurred by donor
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Datana caterpillars example
 Brightly
colored and assume specific pose
when threatened
 Predator has to eat one to learn to avoid them
 Death of individual in group of related
caterpillars benefits siblings
 r =0.5, B=50, and C=1, then 25(0.5x50)>1 so
genes will spread
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Altruism in social insects due to genetics
and lifestyle
 Most
extreme form of altruism is sterile castes
in social insects
Eusociality – workers (females) help queen raise
offspring
 Haplodiploidy – females are diploid, males are
haploid, females are more related to their sisters
(0.75) than they would be to their own offspring
(0.5)
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 Existence
of eusocial mammals predicted
based on lifestyle
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Naked mole rats have a queen who suppresses
reproduction in other females
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Reciprocal altruism
 Cost
to the altruist offset by likelihood of a
return benefit
 Female vampire bats will share food
 Unrelated females are more likely to share
food with those that had recently shared with
them
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Mating systems
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Natural selection favors production of the rarer
sex so that the sex ratio is kept balanced at 1:1
Monogamy – each individual mates exclusively
with one partner
Polygamy – individuals mate with more than one
partner
– one male mates with many females
 Polyandry – one female mates with many males
 Polygyny
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
Sexual selection
 Promotes
traits that will increase an
organism's mating success
 2 forms
Intersexual – member of one sex chooses mate
based on particular characteristics
 Intrasexual – members of one sex compete over
partners with the winner performing most of the
matings
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Female mate choice
hangingflies demand a nuptial gift –
allows female to produce more eggs and
allows male to copulate longer
 Female sticklebacks prefer males that shake
more during courtship as evidence that he will
be a better parent
 Choices based on plumage color or courtship
displays – widowbird with experimentally
lengthened tails attracted more females and
fathered more clutches
 Female
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Mate competition between individuals
 In
many species, females do not actively
choose between mates
 Instead they mate with competitively superior
males
 Dominance determined by fighting or
ritualized sparring
 Male-male competition produces males
substantially larger than females
 Small males can still father offspring by
intercepting females
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Monogamy
 One male mates with one female
 Males and females generally similar
in body
size and appearance
 Mate-guarding hypothesis – males stay with a
female to protect her from being fertilized by
other males
 Male assistance hypothesis – males remain
with females to help them rear offspring – he
would have few surviving offspring if he did
not
 Female-enforced monogamy hypothesis–
female interferes with male attracting other
females
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
Polygyny
 One
male mates with more than one female
 Females mate with only one male
 Associated with uniparental care of young
 Males contribute little to raising young
 Sexual dimorphism typical
 Types
Resource based polygyny – patchy distribution of
resource and female visits for resource
 Harem mating structure – females naturally
congregate and male controls area
 Communal courting – males display in lek, females
mate after males display
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Polyandry
 One
female mates with several males
 Rarer
 Female is larger of the sexes
 Female spotted sandpiper reproductive
success limited only by the number of males
she can find to incubate her eggs
 Male pipefish have brood pouches and female
produces enough eggs for 2 male brood
pouches if she can find another male
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