You are observing a grouse population in which there are two feather phenotypes in males. One is relatively dark and blends into shadows well, and the other is relatively bright, and so is more obvious to predators. The females are uniformly dark-feathered. Observing the frequency of mating between females and the two types of males, you have recorded the following:
matings with dark-feathered males: 13
matings with bright-feathered males: 32
Propose a hypothesis to explain why females apparently prefer bright feathered males. What selective advantage might there be in choosing a male with alleles that make it more susceptible to predation? What other data would help to test the hypothesis?
Answer
A farmer uses a new pesticide. He applies the pesticide as directed by the manufacturer and loses about 15% of his crop to insects. A farmer in the next state learns of these results, uses three times as much pesticide and loses only 3% of her crop to insects. Each farmer follows this pattern for 5 years. At the end of 5 years, the first farmer is still losing about 15% of his crop to insects, but the second farmer is losing 40% of her crop to insects. How could these observations be interpreted on the basis of natural selection?
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