What Is Life? 2nd Edition by Jay Phelan

Exercise 40

The average time to death from starvation in a fruit fly is about 20 hours. Selecting for increased starvation resistance in fruit flies:
A) has no effect, because starvation resistance is not a trait that influences fruit fly fitness.
B) has little effect, because ongoing mutation continuously reduces starvation resistance, counteracting any benefits from selection.
C) cannot increase their survival time, because there is no genetic variation for this trait.
D) has no effect, because starvation resistance is too complex a trait, dependent on the effects of too many genes.
E) can produce populations in which the average time to death from starvation is 160 hours.