Transcript History, Natural Selection

Animal Behavior:
Why (and how) do animals do what they do?
Picture: Animal cognition.net
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Aristotle (384-322 B.C.):
Observational work in zoology
Anatomy
Embryology
Behavior:
Social organization
Characteristics: Vivipary
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5/13/08: Natural Selection
and History of Animal Behavior
Lecture objectives:
1.
Understand Darwin’s
theory of evolution by natural selection
2.
Identify the major people and questions
that guided the development
of the modern study of animal behavior
3
The views on relationships between species have
progressed over time
4
Darwin set the stage for the study of animal
behavior through his theory of natural selection
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Evolution by natural selection is inevitable
if 3 conditions are met:
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1.
Variation:
2.
Heredity:
3.
Differences in reproductive success:
Survival of the “fittest”
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Evolution by natural selection acts at the genetic level
Peppered moth:
Gene for color
has two alleles (forms): R, r
RR, Rr
rr
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Example of natural selection in action:
moths in England during the Industrial Revolution
I tawt I taw
a peppered
moth!
1
Proportion of
light moths
0
Brown trunks increase
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What would a population look like over time
if one of Darwin’s 3 conditions is not met?
1.
No Variation?
2.
No Heredity?
3.
No Differences in
reproductive success?
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Biologists often seek to understand behavior
through the lens of natural selection
“How does this trait promote reproductive success?”
Logic:
Conditions of n.s. apply to
So species have been
So the traits we observe today are a
So these traits probably exist because
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Example of Darwinian approach: How does infanticide by
male langurs increase the male’s reproductive success?
Tendency for infanticide
x
x
No tendency for infanticide
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Example of Darwinian approach: Why might a (former)
mother langur be willing to mate with this new male?
Tendency to mate
x
No tendency to mate
x
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How might building an elaborate bower enhance
the reproductive success of male bowerbirds?
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The history of the study of animal behavior
Pavlov
Thorndike
Skinner
Behaviorism
Aristotle
Comparative
Psychology
Darwin
1900
350 B.C.
1859
1973
Ethology
Nobel Prize
Modern
Animal
Behavior
Lorenz
von Frisch
Tinbergen
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Pavlov:
Classical Conditioning
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Thorndike and Skinner:
Operant Conditioning
(Trial-and-error learning)
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The history of the study of animal behavior
Pavlov
Thorndike
Skinner
Behaviorism
Aristotle
Comparative
Psychology
Darwin
1900
350 B.C.
1859
1973
Ethology
Nobel Prize
Modern
Animal
Behavior
Lorenz
von Frisch
Tinbergen
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Karl von Frisch:
Communication & Sensory abilities
in Honeybees
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Konrad Lorenz (1903-1989):
Instinct, Imprinting & Motivation
Form of imprinting:
“Westermarck effect”
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Niko Tinbergen (1907-1988):
What features of the environment
do animals respond to?
Sign stimuli
Aggression in 3-spined sticklebacks
Fixed action patterns
Egg-rolling behavior in
graylag geese
Experiments!
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Behaviorist or Ethologist? You decide!
?
“Give me a dozen healthy infants…and my own
specified world to bring them up in and I'll guarantee
to take any one at random and train him to become
any type of specialist I might select – doctor, lawyer,
artist, merchant-chief and, yes, even beggar-man and
thief, regardless of his talents, penchants, tendencies,
abilities, vocations, and race of his ancestors.”
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Behaviorist or Ethologist? You decide!
?
His view:
Each animal has its own subjective universe,
or way of sensing the world around it.
And as a consequence, different animals, even ones
that share the same physical environment,
might have unique sensory experiences.
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The history of the study of animal behavior
Pavlov
Thorndike
Skinner
Behaviorism
Aristotle
Comparative
Psychology
Darwin
1900
350 B.C.
1859
1973
Ethology
Nobel Prize
Modern
Animal
Behavior
Lorenz
von Frisch
Tinbergen
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The modern study of animal behavior is a
synthesis of behaviorism and ethology
Behaviorists came to recognize that
Ethologists came to recognize that
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The history of the study of animal behavior
Context: Psychology - Learning
“Nurture”
Labwork: Mammals, Pigeons
Pavlov
Thorndike
Skinner
Behaviorism
Aristotle
Comparative
Psychology
Darwin
1900
350 B.C.
1859
1973
Ethology
Context: Biology - Evolution
“Nature”
Fieldwork: Insects, bird, fish
Nobel Prize
Modern
Animal
Behavior
Lorenz
von Frisch
Tinbergen
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Darwin discussion
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1.
Variation: What might maintain this?
2.
Heredity: Are all traits hereditary?
3.
Differences in reproductive success:
What might make some animals be
less successful at producing offspring?
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