midterm1_key-1

midterm1_key-1 - IB 144 Psych 115B Fall 2009 KEY TO MIDTERM...

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IB 144 / Psych 115B Fall 2009 KEY TO MIDTERM 1 1. B. Hopefully, indirect fitness benefits were the first thing you thought of in a situation like this. If not, none of the other choices make sense in terms of how natural selection (and its subsets kin and sexual selection) should operate on individuals. 2. A. The turkeys are a classic example of the overlap between kin selection and sexual selection that I diagrammed in class when I drew the concentric circles of selection. You already identified kin selection as important in question 1. Sexual selection is clearly involved since males are competing for access to mates and natural selection is involved because predation limits the size and duration of cooperative male coalitions. 3. D. The question indicates that this is an example of good genes sexual selection. As a result, the male trait in question must be costly – this is the only way that females can be sure that the trait is “honest.” Choices A and C refer to the Fisherian model of female choice. Choice B is incorrect because in both models both the trait and the preference must be heritable for selection to act on them. 4. B. Recall that the control should be exactly the same as the experiment with regard to everything EXCEPT the target variable, in this case the injection of the anti- parasite medication. Thus, you should inject subordinate males with something that will not affect their parasite loads. Saline is a good choice, since it’s a natural bodily substance that shouldn’t affect parasites. 5. The correct answer is r > 1/6. To get full credit for your answer, you had to use Hamilton’s equation to calculate this value. Thus, we looked for Hamilton’s equation, the equation with the fitness values plugged in, and, finally, the statement of the minimal value for r. 6. D. If we state that different patterns of male behavior are true genetic alternatives, we are saying that the specific strategy that a male uses is determined genetically, meaning that it is inherited. This is in contrast to conditional strategies in which males can pursue any of the alternatives but choose the best strategy based on their current phenotypic condition. 7. D. This one was a bit subtle. If the heritability of the male strategies is 0, this means that there is no genetic component – the strategies are determined solely by the environment. This does not mean that they are conditional (A), since conditional strategies are the result of natural selection and therefore must be heritable in some way. For the same reason, the alternatives cannot be products of sexual 1
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selection (B). They may still affect male fitness (C), but selection cannot act on the tendency to have higher fitness because this tendency is not heritable. 8.
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This note was uploaded on 02/11/2010 for the course IB Animal Beh taught by Professor Lacey during the Fall '09 term at Berkeley.

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midterm1_key-1 - IB 144 Psych 115B Fall 2009 KEY TO MIDTERM...

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