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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
PowerPoint Lectures forBio logy, Seventh Edit ion
Neil Campbell and Jane Reece
Lectures by Chris Romero
Chapter 51
Behavioral Ecology
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Overview: Studying Behavior
Humans have probably studied animalbehavior
For as long as we have lived on Earth
As hunters
Knowledge of animal behavior was essential to
human survival
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Cranes are birds that have captivated peoples
interest Possibly because they are large and their
behavior is easily observed
Figure 51.1
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The modern scientific discipline of behavioral
ecology Extends observations of animal behavior by
studying how such behavior is controlled and
how it develops, evolves, and contributes to
survival and reproductive success
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Concept 51.1: Behavioral ecologists distinguish
between proximate and ultimate causes ofbehavior
The scientific questions that can be asked
about behavior can be divided into two classes
Those that focus on the immediate stimulus
and mechanism for the behavior
Those that explore how the behavior
contributes to survival and reproduction
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What Is Behavior?
Behavior
Is what an animal does and how it does it
Includes muscular and nonmuscular activity
Figure 51.2
Dorsal fin
Anal fin
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Learning
Is also considered a behavioral process
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Proximate and Ultimate Questions
Proximate, or how, questions about behavior
Focus on the environmental stimuli that triggera behavior
Focus on the genetic, physiological, and
anatomical mechanisms underlying abehavioral act
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Ultimate, or why, questions about behavior
Address the evolutionary significance of abehavior
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Ethology
Ethology is the scientific study of animal
behavior Particularly in natural environments
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Mid 20th-century ethologists
Developed a conceptual framework defined bya set of questions
These questions
Highlight the complementary nature of
proximate and ultimate perspectives
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F ixed Action Patterns
A fixed action pattern (FAP)
Is a sequence of unlearned, innate behaviorsthat is unchangeable
Once initiated, is usually carried to completion
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A FAP is triggered by an external sensory
stimulus Known as a sign stimulus
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In male stickleback fish, the stimulus for attack
behavior Is the red underside of an intruder
Figure 51.3a
(a)A male three-spined stickleback fish shows its red underside.
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When presented with unrealistic models
As long as some red is present, the attackbehavior occurs
Figure 51.3b
(b)The realistic model at the top, without a red underside, produces no
aggressive response in a male three-spined stickleback fish. The
other models, with red undersides, produce strong responses.
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Proximate and ultimate causes for the FAP
attack behavior in male stickleback fish
Figure 51.4ULTIMATE CAUSE: By chasing away other male sticklebacks, a male decreases
the chance that eggs laid in his nesting territory will be fertilized by another male.
BEHAVIOR: A male stickleback fish attacks other male sticklebacks that invade its nesting
territory.
PROXIMATE CAUSE: The red belly of the intruding male acts as a sign stimulus
that releases aggression in a male stickleback.
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Imprinting
Imprinting is a type of behavior
That includes both learning and innatecomponents and is generally irreversible
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Imprinting is distinguished from other types of
learning by a sensitive period A limited phase in an animals development
that is the only time when certain behaviors
can be learned
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An example of imprinting is young geese
Following their mother
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Konrad Lorenz showed that
When baby geese spent the first few hours oftheir life with him, they imprinted on him as
their parent
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There are proximate and ultimate causes for
this type of behavior
Figure 51.5
BEHAVIOR: Young geese follow and imprint on their mother.
PROXIMATE CAUSE:During an early, critical developmental stage, the young
geese observe their mother moving away from them and calling.
ULTIMATE CAUSE:On average, geese that follow and imprint on their mother
receive more care and learn necessary skills, and thus have a greater chance of
surviving than those that do not follow their mother.
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Conservation biologists have taken advantage
of imprinting
In programs to save the whooping crane from
extinction
Figure 51.6
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Concept 51.2: Many behaviors have a strong
genetic component
Biologists study the ways both genes and the
environment
Influence the development of behavioralphenotypes
Behavior that is developmentally fixed
Is called innate behavior and is under strong
genetic influence
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Directed Movements
Many animal movements
Are under substantial genetic influence
These types of movements
Are called directed movements
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Kinesis
A kinesis
Is a simple change in activity or turning rate inresponse to a stimulus
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Sow bugs
Become more active in dry areas and lessactive in humid areas
Figure 51.7a
Dry open
area
Moist site
under leaf
(a) Kinesis increases the chance that a sow bug will encounter and
stay in a moist environment.
T i
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Taxis
A taxis
Is a more or less automatic, orientedmovement toward or away from a stimulus
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Many stream fish exhibit positive rheotaxis
Where they automatically swim in an upstreamdirection
Figure 51.7b
Direction
of river
current
(b) Positive rheotaxis keeps trout facing into the current, the direction
from which most food comes.
Mi ti
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Migration
Many features of migratory behavior in birds
Have been found to be geneticallyprogrammed
Figure 51.8
A i l Si l d C i ti
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Animal Signals and Communication
In behavioral ecology
A signal is a behavior that causes a change inanother animals behavior
Communication
Is the reception of and response to signals
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Animals communicate using
Visual, auditory, chemical, tactile, andelectrical signals
The type of signal used to transmit information
Is closely related to an animals lifestyle and
environment
Ch i l C i ti
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Chemical Communication
Many animals that communicate through odors
Emit chemical substances called pheromones
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When a minnow or catfish is injured
An alarm substance in the fishs skin dispersesin the water, inducing a fright response among
fish in the area
Figure 51.9a, b
(a) Minnows are widely dispersed in an aquarium
before an alarm substance is introduced.(b) Within seconds of the alarm substance being
introduced, minnows aggregate near the
bottom of the aquarium and reduce their movement.
Auditory Communication
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Auditory Communication
Experiments with various insects
Have shown that courtship songs are undergenetic control
Charles Henry, Luca Martnez, and ent Holsinger crossed males and females of Chrysoperla plorabunda and Chrysoperla johnsoni, two
morphologically identical species of lacewings that sing different courtship songs.
EXPERIMENT
SONOGRAMS
Chrysoperla plorabundaparent
Vibration
volleysStandard
repeating
unit
Chrysoperla johnsoniparent
Volley period
crossed
with
Standard repeating unit
The researchers recorded and compared the songs of the male and female parents with
those of the hybrid offspring that had been raised in isolation from other lacewings.
Volley
period
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The F1hybrid offspring sing a song in which the length of the standard repeating unit is similar to that sung by the Chrysoperla plorabunda parent, but the
volley period, that is, the interval between vibration volleys, is more similar to that of the Chrysoperla johnsoniparent.
RESULTS
The results of this experiment indicate that the songs sung by Chrysoperla plorabunda and Chrysoperla
johnsoni are under genetic control.CONCLUSION
Standard repeating unit
Volley
period
F1hybrids, typical phenotype
Genetic Influences on Mating and Parental Behavior
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Genetic Influences on Mating and Parental Behavior
A variety of mammalian behaviors
Are under relatively strong genetic control
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Research has revealed the genetic and neural basis
For the mating and parental behavior of male prairievoles
Figure 51.11
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Concept 51.3: Environment, interacting with an
animals genetic makeup, influences the
development of behaviors
Research has revealed
That environmental conditions modify many ofthe same behaviors
Dietary Influence on Mate Choice Behavior
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Dietary Influence on Mate Choice Behavior
One example of environmental influence on
behavior
Is the role of diet in mate selection by
Drosophila mojavensis
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Laboratory experiments have demonstrated
That the type of food eaten during larval developmentinfluences later mate choice in females
Figure 51.12
William Etges raised a D. mojavensispopulation from Baja California
and a D. mojavensis population from Sonora on three different culture media: artificial
medium, agria cactus (the Baja host plant), and organ pipe cactus (the Sonoran host
plant). From each culture medium, Etges collected 15 male and female Baja D. mojavensis
pairs and 15 Sonoran pairs and observed the numbers of matings between males and
females from the two populations.
EXPERIMENT
When D. mojavensis had been raised on artificial medium, females from the
Sonoran population showed a strong preference for Sonoran males (a). When D. mojavensis had been raised on cactus medium, the Sonoran females mated with Baja and Sonoran
males in approximately equal frequency (b).
RESULTS
The difference in mate selection shown by females that developed on
different diets indicates that mate choice by females of Sonoran populations of D. mojavensis
is strongly influenced by the dietary environment in which larvae develop.
CONCLUSION
100
75
50
25
0
Artificial Organ pipe cactus Agria cactus
Culture medium
With Baja males
With Sonoran
males
(b)
Proportionofmatings
bySonoranfemales
(a)
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Therese Markow and Eric Toolson proposed
That the physiological basis for the observedmate preferences was differences in
hydrocarbons in the exoskeletons of the flies
Figure 51.13
Social Environment and Aggressive Behavior
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Social Environment and Aggressive Behavior
Cross-fostering studies in California mice and
white-footed mice
Have uncovered an influence of social
environment on the aggressive and parental
behaviors of these mice
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Influence of cross-fostering on male mice
Table 51.1
Learning
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Learning
Learning is the modification of behavior
Based on specific experiences
Learned behaviors
Range from very simple to very complex
Habituation
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Habituation
Habituation
Is a loss of responsiveness to stimuli thatconvey little or no information
Spatial Learning
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Spatial Learning
Spatial learning is the modification of behavior
Based on experience with the spatial structureof the environment
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In a classic experiment, Niko Tinbergen
Showed how diggerwasps use landmarks
to find the entrances
to their nests
After the mother visited the nest and flew away, Tinbergen
moved the pinecones a few feet to one side of the nest.
Figure 51.14CONCLUSION
A female digger wasp excavates and cares for four
or five separate underground nests, flying to each nest daily with food
for the single larva in the nest. To test his hypothesis that the wasp
uses visual landmarks to locate the nests, Niko Tinbergen marked onenest with a ring of pinecones.
EXPERIMENT
Nest
When the wasp returned, she flew to the center of
the pinecone circle instead of to the nearby nest. Repeating the
experiment with many wasps, Tinbergen obtained the same results.
RESULTS
The experiment supported the hypothesis
that digger wasps use landmarks to keep track of their nests.
NestNo Nest
Cognitive Maps
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Cognitive Maps
A cognitive map
Is an internal representation of the spatialrelationships between objects in an animals
surroundings
Associative Learning
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Associative Learning
In associative learning
Animals associate one feature of theirenvironment with another
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Classical conditioning is a type of associative
learning
In which an arbitrary stimulus is associated
with a reward or punishment
Figure 51.15
Before stimulus
Influx of water alone
Influx of alarm substances
Influx of pike odor
Day 1 Day 3
Control
group
Control
group
Experimental
groupExperimental
group
Relativeactivitylevel
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Operant conditioning is another type of
associative learning
In which an animal learns to associate one of
its behaviors with a reward or punishment
Figure 51.16
Cognition and Problem Solving
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Cognition and Problem Solving
Cognition is the ability of an animals nervous
system
To perceive, store, process, and use
information gathered by sensory receptors
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7
Problem solving can be learned
By observing the behavior of other animals
Figure 51.17
Genetic and Environmental I nteraction in Learning
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Genetic and Environmental I nteraction in Learning
Genetics and environment can interact
To influence the learning process
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Concept 51.4: Behavioral traits can evolve by
natural selection
Because of the influence of genes on behavior
Natural selection can result in the evolution of
behavioral traits in populations
Behavioral Variation in Natural Populations
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p
When behavioral variation within a species
Corresponds to variation in the environment, itmay be evidence of past evolution
Variation in Prey Selection
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y
Differences in prey selection in populations of
garter snakes
Are due to prey availability and are evidence of
behavioral evolution
Figure 51.18a, b
(a) A garter snake (Thamnophis
elegans)
(b) A banana slug (Ario l imus
cal i forn icus); not to scale
Variation in Aggressive Behavior
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gg
Funnel spiders living in different habitats
Exhibit differing degrees of aggressiveness indefense and foraging behavior
Figure 51.19
50
40
30
20
10
0
Timetoattack(seconds)
Field Lab-raised
generation 1
Lab-raised
generation 2
Desert
grassland
population
Riparian
population
60
Population
Experimental Evidence for Behavioral Evolution
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p
Laboratory and field experiments
Can demonstrate the evolution of behavior
Laboratory Studies of DrosophilaForaging Behavior
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p
Studies of Drosophilapopulations raised in high-
and low-density conditions
Show a clear divergence in behavior linked to
specific genes
Figure 51.20
14
12
10
8
6
2
0
A
veragepathlength(cm)
4
L1 L2 L3 H1 H2 H3 H4 H5
D. Melanogasterlineages
Low population
density
High population
density
Migratory Patterns in Blackcaps
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g y p
Field and laboratory studies of Blackcap birds
Have documented a change in their migratorybehavior
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Birds placed in funnel cages
Left marks indicating the direction they weretrying to migrate
Figure 51.21a
(a) Blackcaps placed in a funnel cage left marks indicating the
direction in which they were trying to migrate.
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Migratory orientation of wintering adult birds
captured in Britain
Was very similar to that of laboratory-raised birds
Figure 51.21b
(b) Wintering blackcaps captured in Britain and their laboratory-raised
offspring had a migratory orientation toward the west, while
young birds from Germany were oriented toward the southwest.
N
E
S
W
Adults from
Britain and
F1 offspring
of British
adults
N
E
S
WYoung
from SW
Germany
Mediterranean
Sea
BRITAIN
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Concept 51.5: Natural selection favors
behaviors that increase survival and
reproductive success
The genetic components of behavior
Evolve through natural selection
Behavior can affect fitness
Through its influence on foraging and matechoice
Foraging Behavior
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Optimal foraging theory
Views foraging behavior as a compromisebetween the benefits of nutrition and the costs
of obtaining food
Energy Costs and Benefits
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Reto Zach
Conducted a cost-benefit analysis of feedingbehavior in crows
The crows eat molluscs called whelks
But must drop them from the air to crack the
shells
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Zach determined that the optimal flight height
in foraging behavior
Correlated with a fewer number of drops,
indicating a trade-off between energy gained
(food) and energy expended
Figure 51.22
60
50
40
30
20
10
0
Averagenum
berofdrops
2 3 5 7 15
Average number of drops
Drop height
preferred
by crows
125
100
25
75
50
Total flight height
Totalflightheight(numb
erofdrops
d
ropheight)
Height of drop (m)
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In bluegill sunfish
Prey selection behavior is related to prey density
Figure 51.23
Low prey density High prey density
33%33%
33%
32.5%32.5%
35%
2%40%
57%
100%
50%35%
14%
33%
33%33%
Small prey
Medium prey
Large prey
Small prey
Medium preyLarge prey
Small prey
Medium prey
Large prey
Percentage available
Predicted percentage in diet
Observed percentage in diet
Large prey at
far distance
Small prey at
middle distanceSmall prey at
close distance
Risk of Predation
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Research on mule deer populations
Has shown that predation risk affects wherethe deer choose to feed
Figure 51.24
70
60
40
30
20
10
0
Pre
dationoccurrence(%)
50
Relativedeeruse
Relative deer use Predation
risk
Open Forest edge
Habitat
Forest interior
0
5
10
15
20
Mating Behavior and Mate Choice
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Mating behavior
Is the product of a form of natural selection callsexual selection
Mating Systems and Mate Choice
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The mating relationship between males and
females
Varies a great deal from species to species
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In many species, mating is promiscuous
With no strong pair-bonds or lastingrelationships
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In monogamous relationships
One male mates with one female
Figure 51.25a
(a) Since monogamous species, such as these trumpeter swans, are
often monomorphic, males and females are difficult to distinguish
using external characteristics only.
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In a system called polygyny
One male mates with many females
The males are often more showy and larger
than the females
Figure 51.25bAmong polygynous species, such as elk, the male (left) is
often highly ornamented.
(b)
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In polyandrous systems
One female mates with many males
The females are often more showy than the males
Figure 51.25c
(c) In polyandrous species, such as these Wilsons phalaropes, females
(top) are generally more ornamented than males.
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The needs of the young
Are an important factor constraining theevolution of mating systems
The certainty of paternity
Influences parental care and mating behavior
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In species that produce large numbers of
offspring
Parental care is at least as likely to be carried
out by males as females
Figure 51.26
Eggs
Sexual Selection and Mate Choice
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In intersexual selection
Members of one sex choose mates on thebasis of particular characteristics
Intrasexual selection
Involves competition among members of one
sex for mates
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Mate Choice by Females
Male zebra finches
Are more ornate than females, a trait that may
affect mate choice by the females
Figure 51.27
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Imprinting of female chicks on males with more
ornamentation
Affects mate
selection as
adults
Figure 51.28
Experimental Groups Control Group
Parents notornamented
Both parentsornamented
Malesornamented
Femalesornamented
Results
Females reared byornamented parents
or ornamented fathers
preferred ornamented
males as mates.
Females reared by
ornamented mothers or
nonornamented parentsshowed no preference
for either ornamented or
nonornamented males.
Males reared by all experimental groups showed no
preference for either ornamented or nonornamented
female mates.
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The size of eyestalks in stalk-eyed flies
Affects which males the females choose tomate with
Figure 51.29
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Male Competition for Mates
Male competition for mates
Is a source of intrasexual selection that can
reduce variation among males
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Such competition may involve agonistic
behavior
An often ritualized contest that determines
which competitor gains access to a resource
Figure 51.30
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Morphology affects the mating behavior
In isopods of the same species that aregenetically distinct
Figure 51.31
Large Paracerceis males
defend harems of females
within intertidal sponges.
Tiny males are
able to invade
and live within
large harems.
males mimic female morphology and
behavior and do not elicit a defensive
reponse in males and so are able to
gain access to guarded harems.
Applying Game Theory
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Game theory evaluates alternative behavioral
strategies in situations
Where the outcome depends on each
individuals strategy and the strategy of other
individuals
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Mating success of male side-blotched lizards
Was found to be influenced by malepolymorphism and the abundance of different
males in a given area
Figure 51.32
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Concept 51.6: The concept of inclusive fitness
can account for most altruistic social behavior
Many social behaviors are selfish
Natural selection favors behavior
That maximizes an individuals survival and
reproduction
Altruism
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On occasion, some animals
Behave in ways that reduce their individualfitness but increase the fitness of others
This kind of behavior
Is called altruism, or selflessness
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In naked mole rat populations
Nonreproductive individuals may sacrifice theirlives protecting the reproductive individuals
from predators
Figure 51.33
Inclusive Fitness
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Altruistic behavior can be explained by
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
Hamiltons Rule and Kin Selection
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Hamilton proposed a quantitative measure
For predicting when natural selection wouldfavor altruistic acts among related individuals
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The three key variables in an altruistic act are
The benefit to the recipient
The cost to the altruist
The coefficient of relatedness
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The coefficient of relatedness
Is the probabilitythat two relatives
may share the
same genes
Figure 51.34
Parent A Parent B
OR
Sibling 1 Sibling 2
1/2(0.5)
probability
1/2(0.5)
probability
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Natural selection favors altruism when the
benefit to the recipient
Multiplied by the coefficient of relatedness
exceeds the cost to the altruist
This inequality
Is called Hamiltons rule
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Kin selection is the natural selection
That favors this kind of altruistic behavior byenhancing reproductive success of relatives
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An example of kin selection and altruism
Is the warning behavior observed in Beldingsground squirrels
Male
Female
Age (months)
Meandistance
m
ovedfrom
n
atalburrow
(m)
300
200
100
00 2 3 4 12 13 14 15 25 26
Figure 51.35
Reciprocal Altruism
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Altruistic behavior toward unrelated individuals
Can be adaptive if the aided individual returnsthe favor in the future
This type of altruism
Is called reciprocal altruism
Social Learning
S
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Social learning
Forms the roots of culture
Culture can be defined as a system of
information transfer through observation or
teaching
That influences the behavior of individuals in a
population
Mate Choice Copying
M t h i i
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Mate choice copying
Is a behavior in which individuals in apopulation copy the mate choice of others
Thi t f b h i
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This type of behavior
Has been extensively studied in the guppyPoecilia reticulata
Figure 51.36
Male guppies
with varying
degrees of
coloration
Control Sample
Female guppies prefer
males with more orange
coloration.
Experimental Sample
Female model
engaged in
courtship with
less orange
male
Female guppies prefer less
orange males that are associated
with another female.
Social Learning of Alarm Calls
V t k
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Vervet monkeys
Produce a complex set of alarm calls
I f t k i di i i ti l
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Infant monkeys give undiscriminating alarm
calls at first
But learn to fine-tune them by the time they are
adults
Figure 51.37
N th i
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No other species
Comes close to matching the social learning andcultural transmission that occurs among humans
Figure 51.38
Evolution and Human Culture
H lt
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Human culture
Is related to evolutionary theory in the distinctdiscipline of sociobiology
H b h i lik th t f th i
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Human behavior, like that of other species
Is the result of interactions between genes andenvironment
However, our social and cultural institutions
May provide the only feature in which there is
no continuum between humans and other
animals