The Adaptationist Approach
ZOL 313
May 22, 2008
The Adaptationist Approach
Objectives:
1. Be able to define an adaptation and identify
adaptive behaviors.
2. Become familiar with some different ways to test
adaptationist hypotheses.
3. Understand why adaptations are not perfect.
4. Understand the concept of inclusive fitness and
be able to calculate when it using Hamilton’s Rule
ZOL 313
May 22, 2008
What is an adaptation?
Fitness:
Example:
Moller 1994 - Fig. 4.4
- Fig. 6.15
The “adaptationist approach” to studying animal
behavior involves
How can we test adaptive hypotheses?
1.Experiments
2.Comparative Method
3.Optimality Theory
4.Game thoery
1.Using experiments to test adaptive hypotheses
Example:
1. Using experiments to test adaptive hypotheses
Hypothesis 1:
Prediction:
1. Using experiments to test adaptive hypotheses
Hypothesis 2:
Prediction a:
Prediction b:
Prediction c:
1. Using experiments to test adaptive hypotheses
Hypothesis 3:
Prediction a:
1. Using experiments to test adaptive hypotheses
Hypothesis 3:
Prediction b:
2. Using the comparative method to test
adaptive hypotheses
Example:
2. Using the comparative method to test
adaptive hypotheses
Convergent evolution:
Divergent evolution:
3. Using Optimality Theory to test adaptive
hypotheses
3. Using Optimality Theory to test adaptive
hypotheses
Example:
Benefit
Cost
4. Using Game Theory to test adaptive
hypotheses
Why aren’t adaptations perfect?
1.Lack of genetic variation/appropriate
mutations
2.Tradeoffs with other traits/pleiotropy
3.Coevolution
Why aren’t adaptations perfect?
1. Lack of genetic variation/appropriate mutations
Example:
Example:
Why aren’t adaptations perfect?
2. Tradeoffs/pleiotropy
Example:
Pleiotropy:
Example:
Why aren’t adaptations perfect?
2. Tradeoffs/pleiotropy
Example: The “Farm Fox Experiment”
After many generations, their farm foxes
also became more “dog-like” in:
1.
2.
http://youtube.com/watch?v=mzTcmE-pMLU
Why aren’t adaptations perfect?
3. Coevolution
Example:
The “
Hypothesis”
"Well, in our country," said Alice, still panting
a little, "You'd generally get to somewhere
else--if you ran very fast for a long time as
we've been doing."
"A slow sort of country!" said the Queen.
"Now, here, you see, it takes all the running
you can do, to keep in the same place. If
you want to get somewhere else, you must
run at least twice as fast as that."
Inclusive Fitness
Why help others when you could help yourself?
In order for a behavior to be adaptive…
Inclusive fitness=
Inclusive Fitness
2
2
R=
Hamilton’s Rule:
Example: An inexperienced bird breeding on her own will produce
an average of 1 offspring. If she helps her parents breed instead,
she will help them raise an average of 2 more of her siblings than
they would have without her help.
Should she help??? R=
B=
C=
Inclusive Fitness
Example: