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The Adaptationist Approach
ZOL 313
May 22, 2008
The Adaptationist Approach
ZOL 313
May 22, 2008
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
Moller 1994 - Fig. 4.4
- Fig. 6.15
What is an adaptation?
Fitness:
Example:
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:
Hypothesis 1:
Prediction:
1. Using experiments to test adaptive hypotheses
Hypothesis 2:
Prediction b:
Prediction c:
Prediction a:
1. Using experiments to test adaptive hypotheses
Hypothesis 3:
Prediction a:
1. Using experiments to test adaptive hypotheses
Hypothesis 3:
1. Using experiments to test adaptive hypotheses
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:
Pleiotropy:
Example:
Why aren’t adaptations perfect? 2. Tradeoffs/pleiotropy
Example:
http://youtube.com/watch?v=mzTcmE-pMLU
Example: The “Farm Fox Experiment”
After many generations, their farm foxes also became more “dog-like” in: 1.
2.
Why aren’t adaptations perfect? 2. Tradeoffs/pleiotropy
"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."
Why aren’t adaptations perfect? 3. Coevolution
Example:The “ Hypothesis”
Why help others when you could help yourself?
Inclusive Fitness
Inclusive fitness=
In order for a behavior to be adaptive…
R=
Inclusive Fitness
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=
Hamilton’s Rule:
22
Inclusive Fitness
Example:
