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Understand adaptive behaviors, test hypotheses, inclusive fitness, and why adaptations are not perfect. Explore experiments, comparative method, optimality theory, and game theory.
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The Adaptationist Approach ZOL 313 May 22, 2008
The Adaptationist Approach • Objectives: • Be able to define an adaptation and identify adaptive behaviors. • Become familiar with some different ways to test adaptationist hypotheses. • Understand why adaptations are not perfect. • 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? Moller 1994 - Fig. 4.4 - Fig. 6.15 Fitness: Example:
The “adaptationist approach” to studying animal behavior involves • How can we test adaptive hypotheses? • Experiments • Comparative Method • Optimality Theory • Game thoery
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 Example: Benefit Cost
Why aren’t adaptations perfect? • Lack of genetic variation/appropriate mutations • Tradeoffs with other traits/pleiotropy • 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 R= 2 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: