Does the ability to choose a mate improve offspring fitness in fruit flies? Researchers have studied this

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Does the ability to choose a mate improve offspring fitness in fruit flies? Researchers have studied this by taking female fruit flies and randomly dividing them into two groups; one group is put into a cage with a large number of males and able to freely choose who to mate with, while flies in the other group are each put into individual vials, each with only one male, giving no choice in who to mate with. Females are then put into egg laying chambers, and a certain number of larvae collected. Do the larvae from the mate choice group exhibit higher survival rates? A study published in Nature found that mate choice does increase offspring fitness in fruit flies (with p-value \(<0.02\) ), yet this result went against conventional wisdom in genetics and was quite controversial. Researchers attempted to replicate this result with a series of related experiments,  with data provided in MateChoice.

(a) In the first replication experiment, using the same species of fruit fly as the original Nature study, 6067 of the 10000 larvae from the mate choice group survived and 5976 of the 10000 larvae from the no mate choice group survived. Calculate the p-value.

(b) Using a significance level of \(\alpha=0.05\) and p-value from (a), state the conclusion in context.

(c) Actually, the 10,000 larvae in each group came from a series of 50 different runs of the experiment, with 200 larvae in each group for each run. The researchers believe that conditions differ from run to run, and thus it makes sense to treat each run as a case (rather than each fly). In this analysis, we are looking at paired data, and the response variable would be the difference in the number of larvae surviving between the choice group and the no choice group, for each of the 50 runs. The counts (Choice and NoChoice and difference (Choice - NoChoice) in number of surviving larva are stored in MateChoice. Using the single variable of differences, calculate the \(p\)-value for testing whether the average difference is greater than 0 . 

(d) Using a significance level of \(\alpha=0.05\) and the \(\mathrm{p}\)-value from (c), state the conclusion in context.

(e) The experiment being tested in parts (a)- (d) was designed to mimic the experiment from the original study, yet the original study yielded significant results while this study did not. If mate choice really does improve offspring fitness in fruit flies, did the follow-up study being analyzed in parts (a)- (d) make a Type I, Type II, or no error?

(f) If mate choice really does not improve offspring fitness in fruit flies, did the original Nature study make a Type I, Type II, or no error? 

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Statistics, Enhanced Unlocking The Power Of Data

ISBN: 9781119308843

2nd Edition

Authors: Robin H Lock, Patti Frazer Lock, Kari Lock Morgan, Eric F Lock, Dennis F Lock

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