Download Development of behavior

What determines a particular phenotype?
Nature
versus
Nurture
All behavior is the product of an inextricable
interaction between heredity and environment
during development, so the answer to
all nature-nurture questions is “some of each.”
-Steven Pinker
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5/15/08: Development of Behavior
Lecture objectives:
+
Behavior 1
? Behavior2 ?
1.
Understand that behavior is a product of
gene-environment interactions
2.
Be able to figure out whether differences
in a behavior arise from genetic and/or
environmental differences
3.
Understand features of development
and the adaptive value of learning
2
Behavior is a complex product of gene-environment interactions
Environment
influences expression of genes
(protein production)
Genes
encode
information
Development unfolds over time
3
Example (pgs. 56-59): Gene-env interactions underlie
the development of honeybee foraging
Nurse Forager
(young)
(old)
Nurse
(old)
Forager
(young)
Gene 1
Gene 2
Gene 3
.
.
Gene n
Effect of social environment:
When foragers (old bees)
are scarce, young bees will
rapidly become foragers
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Example cont: Gene-env interactions underlie
the development of honeybee foraging
Concentration
of JH
+
nurse
forager
5
Even learning has a genetic contribution
Gene-environment interactions Example:
Different species show
different imprinting tendencies
Learning
Blue tit
Great tit
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What determines a particular phenotype?
Nature
X
versus
Nurture
All behavior is the product of an inextricable
interaction between heredity and environment
during development, so the answer to
all nature-nurture questions is “some of each.”
-Steven Pinker
Info in genes is only expressed
Development & learning require the
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Lecture objectives:
+
Behavior 1
? Behavior2 ?
1.
Understand that behavior is a product of
gene-environment interactions
2.
Be able to figure out whether differences
in a behavior arise from genetic and/or
environmental differences
3.
Understand features of development
and the adaptive value of learning
8
Members of the same species often differ in behavior
Black-capped
chickadee:
caching behavior
What underlies differences in development/behavior?
- differences in genetic info?
- differences in environmental inputs?
- both?
9
Differences in development/behavior can arise
from environmental differences
Idea:
Environment
A
Behavior/Phenotype
1
Environment
B
Behavior/Phenotype
2
10
Example: social behavior differences in paper
wasps arise from early olfactory experiences
Demonstrated by manipulating
Can experience shape a wasp’s tendency
to tolerate unrelated wasps (nonkin)?
Home nest
Foster nest
I don’t fight with
my sisters!
Tendency
to fight
Sister
wasps
Foster
wasps
Sister
wasps
Foster
wasps
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Differences in development/behavior can arise
from genetic differences
Idea:
Genotype
A
Behavior/Phenotype
1
Genotype
B
Behavior/Phenotype
2
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Example: “Good mommy” behavior differences
in mice arise from genetic differences
Demonstrated by a
fosB
fosB
Expression is
“knocked out”
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Example: Slug-eating behavior differences in
tiger snakes arise from genetic differences
Demonstrated by a
X
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Example: Cotton collection differences in mice
arise from genetic differences
Demonstrated by an
x
?
x
x
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You suspect that the difference in food-caching ability of these two bird
populations has a genetic basis, but there hasn’t been much work done
on this question before. You only have 2 years of funding for the project.
How will your research team go about investigating this question?
1. Come up with a project plan that seems feasible – write/draw your
experimental design
2. List why you chose that design over the other possible designs you
could have chosen
3. List your predictions for the hypothesis that the trait difference has a
genetic basis
Black-capped
chickadee:
caching behavior
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Lecture objectives:
+
Behavior 1
? Behavior2 ?
1.
Understand that behavior is a product of
gene-environment interactions
2.
Be able to figure out whether differences
in a behavior arise from genetic and/or
environmental differences
3.
Understand features of development
and the adaptive value of learning
17
“Normal” development is often robust, even under
adverse genetic or environmental conditions
Gene knockouts
Genetic system likely has high
informational redundancy
Rhesus monkeys develop normal
social behavior with only
15 minutes of socialization/day
18
Sometimes there is more than one form
of “normal” development ( >1 discrete phenotype)
Proximate: what env. cues
activate a different
developmental pathway?
Ultimate: what fitness
benefits do animals gain from
being able to “choose” how
to develop?
19
There are costs and benefits to learning
Adaptive modification of behavior
based on experience
Costs:
Benefits:
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Natural selection favors investment in learning when the
ability to learn confers reproductive advantages
Benefits > Costs
Yoohoo! Where
is my Romeo?
Something isn’t
quite right here…
The ability to learn would probably be
beneficial for male thynnine wasps.
21
An animal’s ability to learn certain associations or solve
certain problems often makes biological sense
Example: Rats have an easy time learning certain
associations and a hard time learning others
22
An animal’s ability to learn certain associations or solve
certain problems often makes biological sense
Example: Sex differences in spatial learning
ability are linked to home range size
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Summers' remarks on women draw fire
By Marcella Bombardieri, Globe Staff | January 17, 2005
“The president of Harvard University, Lawrence H. Summers, sparked an
uproar at an academic conference Friday when he said that innate
differences between men and women might be one reason fewer women
succeed in science and math careers. Summers also questioned how much
of a role discrimination plays in the dearth of female professors in science
and engineering at elite universities.”
What is your reply to the following assertions? Explain your answers.
•
•
•
•
•
Genes determine the ability of women to succeed in science.
Upbringing and culture determine the ability of women to succeed in science
Differences in the abilities of men and women to pursue scientific careers
might arise from genetic differences
Differences in the abilities of men and women to pursue scientific careers
might arise from cultural differences
There is a gene or group of genes that determines scientific ability.
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