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Chapter 51
Behavioral Ecology
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Behavioral Ecology
The scientific observation of animal
behavior, what controls it, how it
develops, evolves, and contributes to
the reproductive success of an
organism.
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Behavioral Ecology
Understanding animal behavior is
important to conserving endangered
species and controlling the spread of
infectious diseases.
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Animal Behavior
There are two main classes of
questions that can be asked about
animal behavior:
1. Those that focus on immediate stimulus
and mechanism of behavior.
2. Those that explore how the behavior
contributes to the survival and reproductive
success.
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What Is Behavior?
It is a phenotype--a product of our
genes.
Behavior is everything an animal does,
and how it does it.
Behavior can also be learned.
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Proximate and Ultimate
Questions
The observation of behavior involves
proximate and ultimate questions.
Proximate questions focus on the stimulus
and what triggers the behavior.
Ultimate questions address the
evolutionary significance of a behavior.
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Proximate Questions
Again, these focus on the stimulus and
what triggers it.
Additionally, it seeks the genetic,
physiological, and anatomical
mechanisms underlying the behavior.
Most importantly: these are mechanism
and development questions.
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Ultimate Questions
Address evolutionary significance of
behavior.
They are often questions that propose a
hypothesis about an observed behavior.
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4 Questions For
Understanding Behavior
Proximate Questions (mechanism and
development):
1. What is the mechanistic basis for
behavior?
2. How does the development of the
animal from the zygote to the mature
individual influence behavior?
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4 Questions For
Understanding Behavior
Ultimate Questions (evolutionary):
3. What is the evolutionary history of the
behavior?
4. How does the behavior contribute to the
survival and reproductive fitness?
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Fixed Patterns and Imprinting
These are two behaviors frequently
studied by ethologists.
Fixed Action Pattern (FAP) is a
sequence of unlearned behaviors that
are essentially unchangable.
Once initiated, they are carried to
completion.
An FAP is triggered by an external
sensory stimulus called a sign stimulus.
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Niko Tinbergen
A classic example
of sign stimuli and
FAP’s:
3-spined male
stickleback fish.
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TIFF (U ncompressed) decompressor
are needed to see this picture.
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Niko Tinbergen
These fish attack other males invading
their nesting area.
The stimulus comes from the red
underside of the intruder.
The stickleback won’t attack any fish
lacking a red-belly. Females don’t have
red bellies.
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Niko Tinbergen
The male sticklebacks will attack fake
models, unrealistic models, anything as
long as some red is present.
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Imprinting
Imprinting is a type of behavior that
involves both learning and innate
components which are generally
irreversible.
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Imprinting
The sensitive period of imprinting only
lasts a limited time, and is the only time
where certain behaviors can be learned.
During periods of bonding, young
imprint on their parents and learn the
basic behaviors of their species.
This is also the period of time where the
parents learn the appearance of their
offspring.
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Imprinting
If bonding doesn’t occur, death of the
offspring usually results.
How and on whom do the young know
to imprint?
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Imprinting
The tendency to respond is innate in the
birds.
The outside world provides an
imprinting stimulus, something to which
the response will be directed.
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Konrad Lorenz
Lorenz experimented with geese.
Extensive research shows that
behavioral traits are influenced by both
genetic and environmental components.
Just as much as are the anatomical and
physiological traits.
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Konrad Lorenz
In fact, Lorenz
showed that geese
(and other
nidifugous birds)
imprint on the first
moving stimulus
they see shortly
after their birth.
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http://www.awakeningpotentials.com/images/imprinting2.jpg
Nature Vs. Nurture
This is not a debate in biology. The
question becomes: How do both the
genes and the environment influence
the development of phenotypes?
Behavior that is developmentally fixed is
called innate behavior (nature).
Behavior that is a result of the environment
is called learned behavior (nurture).
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Studying Nature Vs. Nurture-Movements
Many movements are under genetic
influence and are called “directed
movements.”
Kinesis is a simple change in activity or
turning rate in response to a stimulus.
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Kinesis Example:
 Sow (pill) bugs survive best in moist environments.
 They exhibit kinesis in response to variations in
humidity.
 They become more active only in dry areas.
 They are less active in moist areas.
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Kinesis
 The sow bugs don’t move toward or away
from specific conditions.
 Their increased movement in response to a
dry condition increases the likelihood they will
end up under a moist area.
 When they reach a moist area, they slow
down, and this increases the likelihood they
will stay there.
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Taxis
Taxis is the movement toward or away
from a stimulus.
Positive-toward.
Negative-away.
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Studying Nature Vs. Nurture-Communication
Behavior can be controlled by signals
and responses.
The transmission of, reception of, and
response to signals constitute
communication.
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The Types of Animal Signals
There are two main types:
1. Chemical signals
2. Auditory signals
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Chemical Signals
Chemical signals and pheromones are
genetically controlled and elicit a
behavior in other animals.
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Auditory Signals
Some animals such as birds and
insects sing songs.
Others make noises with their body
parts. These songs are related to
courtship rituals and are under genetic
control (nature), learned control
(nurture), and/or both.
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Natural Selection
Natural selection favors behaviors that
increase survival and reproductive
success.
This can be observed in nature.
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Optimal Foraging
Optimal foraging behavior looks at the
process of hunting for food as a
compromise between the nutritional
benefits of gathering food and the
energy costs of obtaining food.
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Optimal Foraging
According to this theory, natural
selection favors the individuals that
utilize a foraging behavior that
minimizes energy costs while
maximizing energy output.
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Optimal Foraging
Example:
The energy cost-benefit of dropping
molluscs on the coastal rocks by
Northwestern crows.
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Sexual Selection
Recall that it is basically natural
selection for mating success. Mates are
chosen on the basis of their
characteristics.
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Sexual Selection
Determining the basis of sexual
selection in female zebra finches.
Females imprinted on their fathers, and
this was demonstrated by
experimenting with the young finches.
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Sexual Selection
 Male zebra finches have a very
ornate head compared to female
finches.
 On the heads of these birds
were taped red feathers.
 Different nests were examined.
Only males
Males and females
Just females
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Sexual Selection
 These feathers were
taped on before the
eyes of the young
were opened to
determine which sex
played a role in mate
preference.
 The results were
compared to control
groups of offspring
whose parents had no
headdresses.
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Sexual Selection
When the chicks
matured, they were
given a variety of
mate choices.
Males had no
preference at all
toward ornamented
or non-ornamented
females.
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Sexual Selection
Females raised by
non-adorned
parents or females
with a headdress,
had no preference
between
ornamented or
non-ornamented
males.
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Sexual Selection
Females raised in
families with the male
having the red
headdress preferred
males with heads
having headdresses
suggesting females
imprint on their
fathers.
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Sexual Selection
These results also suggest that the
mate choice selection by females plays
a part in the evolution of ornamentation
in male zebra finches.
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Sexual Selection
There are also
forms of male
competition for
mates.
Male competition for
mates is a source of
intrasexual
competition that can
reduce variation.
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Agonistic Behavior
Agonistic behavior, for example, is a
ritualistic type of competition that
determines which competitors gain
access to a resource such as food or
mates.
The outcome can be determined by
strength, size, or in the form of horns,
teeth, etc.
They can be psychological in appearance.
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Preservation of Variation
Although the potential for reduced
variation is there, there also exists a
wide variety of individuals with a lot of
behavioral and morphological
adaptation.
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Preservation of Variation
Despite cases of reduced variation,
there are many species that maintain
variation.
Isopods that live within sponges are an
example.
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, , and  Isopods
These genetically distinct males live
within sponges.
-males defend sponges against other males.
-males mimic the female morphology and
behavior. They get no response from males and have free access to the harem.
-males live within the harem.
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, , and  Isopods’ Mating
Success
The mating success is dependent on the
densities of males and female living within
the sponges.
When one female lives in the sponge, the male fathers most of the offspring.
When there is more than one female, the male fathers 60% of the offspring.
As the harem size increases, the -male’s
reproductive rate increases.
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Conclusions
The information demonstrates that the
reproductive success among the three
different males is equal.
To explain the situation where natural
selection fails to exclude any one
variation (such as the one with the ,,
and  isopods), scientists use what is
known as game theory.
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Game Theory
Game theory is used to explain the
preservation of variation in the face of
competition.
It evaluates the alternative strategies to
a situation where the mating outcome
depends on the strategies of all
individuals involved in the process.
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Game Theory: An Example
The explanation of three different male
phenotypes in populations of side
blotched lizards in the inner coastal
ranges of California.
There are 3 genetically controlled colors:
Orange throats
Blue throats
Yellow throats
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Game Theory
 The frequencies of the individuals in
the general population fluctuate
between the 3 forms.
 The relative mating success of these
three morphs changes over time.
 It’s similar to rock, scissors, paper.
Blue defeats yellow
Orange defeats blue
Yellow defeats orange
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Game Theory
Blue defeats yellow because they
defend a smaller number of females in a
smaller area.
They can’t defend against the
aggressive orange.
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Game Theory
Orange moves in and defeats the less
aggressive blue lizard and takes over a
larger area with many females.
It now comes under attack from the
sneaky yellow.
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Game Theory
Due to the large number of females in
the orange lizard’s territory, he can’t
defend against the sneaky yellow lizard
who eventually takes over.
The cycle then repeats.
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Altruism
The selfless behavior of
some animals that reduces
their fitness, but increases
the overall fitness of the
population.
Example:
Belding’s ground squirrels
give a high pitched warning
signal but draw attention to
themselves.
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http://www.sciencecases.org/kin_selection/squirrels.jpg
Inclusive Fitness
Inclusive fitness helps to
explain altruism. Giving
off the warning signal
helps to preserve the
genes of the individual or
of its close relatives.
Protecting offspring in the
face of death helps to
increase their genetic
complement in the next
generation.
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Reciprocal Altruism
This is a case where an animal will act
altruistically toward another unrelated
animal.
It is relatively rare, and is often
observed in situations were the animals
are likely to meet again where the favor
can be returned.
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Reciprocal Altruism
It is a tit-for-tat strategy.
Cooperation is key.
U of M professors have studied it in
animals.
Non-cooperative animals bring on
retaliation until cooperation is reached.
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Social Learning
This is a way many animals learn
through observation of others.
The transfer of information through
social learning influences the behavior
of others.
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Mate Choice
Copying--A Form
of Social Learning
Individuals in a
population copy the
mate choice of
others.
A classic example of
this involves
guppies.
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http://www.aquariumschatzberger.com/images/lebendgebaerende/15392_guppy-maennchen-rote.JPG
Mate Choice Copying--Social
Learning
 Female guppies in the wild
prefer to mate with males
showing a high percentage
of orange coloration.
 They also copy the mate
choice of other females.
 That is, they mate with
males that have been
successful at attracting
other females.
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Mate Choice Copying--Social
Learning
 The experiment to
demonstrate mate choice
copying was as follows:
Female guppies were given
the choice of mating with
males of varying degrees of
orange coloration.
Females were also given the
choice between males with or
without other females
present.
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Mate Choice Copying--Social
Learning
When the same degree of coloration in
males was offered to females with
another female present and engaging in
a courtship ritual, the experimental
females chose the males with little
coloration.
They were copying the mate choice of the
other females.
This demonstrated social learning.
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Mate Choice Copying--Social
Learning
What this demonstrates:
Below a certain threshold of difference in
male coloration, mate choice copying will
mask the genetically controlled female
preference for orange males.
A female that mates with males that are
attractive to other females may increase the
probability that her male offspring will also
be attractive and have a high reproductive
success.
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