Diane Dodd, of Yale University, divided a fruit-fly population, raising some populations on a starch medium and others on a malt
ose medium. After many generations, natural selection resulted in divergent evolution: Populations raised on starch digested starch more efficiently, while those raised on maltose digested maltose more efficiently. Dodd then put flies from the same or different populations in mating cages and measured mating frequencies. Which of the statements is best supported by the data? A) There is no evidence of reproductive isolation between the starch-adapted flies and maltose-adapted flies. B) The maltose adapted flies will never mate with the starch adapted flies because they are two different species. C) The starch adapted flies and maltose adapted flies appear to now be separate species as defined by the biological species concept. D) The starch adapted flies and maltose adapted flies are not different species but a reproductive barrier is forming between the two populations.
D) The starch adapted flies and maltose adapted flies are not different species but a reproductive barrier is forming between the two populations.
Explanation:
The preference of starch and maltose flies to mate with their own types indicates beginning of the formation of reproductive barrier between them. And the population is exhibiting divergent evolution. It would lead to formation of two different species after several generations. But right now, the barrier is not fully formed as indicated by presence of some mating between two types of flies.
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