[Campbell Biology P.561] In the fruit fly mating preference tests Figure 24.7 , why were all... | Practice Question

In the fruit fly mating preference tests Figure 24.7 , why were all flies reared on a standard cornmeal medium for one generation prior to the tests, rather than continuing to rear them on starch or maltose media?

  • A: To ensure all flies had sufficient nutrients before the mating trials, regardless of their original diet.
  • B: To eliminate any lingering dietary preferences or sensory cues related to the specific food media that might directly influence current mating behavior, thereby isolating the evolved reproductive isolation.
  • C: To provide a neutral environment that would prevent further adaptation to the specific starch or maltose diets during the mating tests.
  • D: To allow the researchers to easily distinguish between the starch-adapted and maltose-adapted flies by their physical appearance after a standardized diet.

Explanation

The purpose of rearing all flies on a standard medium for one generation prior to mating tests is to remove the immediate influence of their current diet on their mating preferences. This allows researchers to assess whether evolved reproductive isolation due to the 40 generations of adaptation to starch or maltose has occurred, rather than simply measuring a preference for a mate that currently smells or tastes like their food source. By standardizing the diet, any observed mating preference reflects the genetic or behavioral divergence that has accumulated.