[Campbell Biology P.550] Based on Figure 23.17 and the 'INTERPRET THE DATA' section, how doe... | Practice Question

Based on Figure 23.17 and the 'INTERPRET THE DATA' section, how does the favor of natural selection for left-mouthed or right-mouthed individuals change between the sample years 1987 and 1990?

  • A: In both 1987 and 1990, natural selection consistently favored left-mouthed individuals.
  • B: In 1987, natural selection favored left-mouthed individuals, but by 1990, it favored right-mouthed individuals.
  • C: In 1987, natural selection favored right-mouthed individuals, but by 1990, it favored left-mouthed individuals.
  • D: In both 1987 and 1990, natural selection consistently favored right-mouthed individuals.

Explanation

In 1987, the frequency of left-mouthed individuals among breeding adults red dot was lower than their frequency in the general population black dot , indicating that right-mouthed individuals were more successful in breeding and thus favored by natural selection. By 1990, the frequency of left-mouthed individuals among breeding adults red dot was higher than in the general population black dot , indicating that left-mouthed individuals were more successful in breeding and thus favored by natural selection. This demonstrates a shift in favor.