Question

Why will there be more darker frogs over time?


A. There will be more darker frogs because they are not being eaten as much as the lighter frogs so more survive and pass on their genes (darker color) to their offspring.


B. The light green frogs evolve into dark green frogs over time.


C. The number of darker frogs gets bigger randomly, there is no reason why.

Answer 1

A is correct.

Explanation: If darker frogs are eaten less often, more of them survive and reproduce. Because color is heritable, their offspring are more likely to be dark. Over generations the frequency of the dark-color genes increases in the population — this is natural selection.

Why B and C are wrong:
- B implies individual frogs change color during their lifetime and then pass that change on; evolution works by changes in allele frequencies between generations, not by individual transformation (this is a Lamarckian idea and incorrect).
- C ignores the selective advantage. Random changes (genetic drift) can alter trait frequencies, but when survival and reproduction differ systematically by color, natural selection is the primary cause of the increase in darker frogs.