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Problem_set_6_new

# Problem_set_6_new - Answers 1 The selection differential S...

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Problem Set 6 Evolution 1. Farmer Smith is raising geese. He wishes to increase their neck length by artificial selection, because trying to stretch their necks just resulted in a flock of annoyed geese. The average neck length when he started was 15 inches. Farmer Smith chose the 20% of his geese that had the longest neck length to breed to create the next generation. The breeders had a mean neck length of 16 inches. Heritability for neck length is 0.2. What will be the population average neck length in the next generation? 2. Using the information in problem 1, what must the average neck length of the breeders be to get a neck length of 16 inches in the next generation? Would this mean that Farmer Smith chose more or fewer geese as breeders (compared to problem 1)?
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Unformatted text preview: Answers: 1. The selection differential, S = 16 - 15 = 1. The response to selection, R = S(h 2 ) = 1(.2) = .2 The neck length in the next generation is the mean of the parental generation plus the response (how do I know this?) and will be 15 + .2 = 15.2 inches 2. Since R = S(h 2 ) = mean of the offspring - mean of the parental generation, and if the mean of the offspring = 16 inches, then 16 - 15 = S(h 2 ) = S (.2) therefore 1/.2 = S = 5 inches. This means that Farmer Smith must have chosen breeders that had necks that were 5 inches longer than the parental generation as a whole, or 20 inches long. To do this he would have chosen fewer geese as breeders (because fewer geese will have this more extreme trait value)....
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