Frequency of the dark (carbonaria) allele in peppered moths in Britain over time.
What evolutionary explanation fits this pattern?
- A
Random drift caused the rise and fall by coincidence
- B
Mutation rate changed in response to industrial pollution
- Ccheck_circle
Pollution darkened tree bark, favoring dark moths via directional selection; cleaner air reversed the selection
- D
Hardy-Weinberg equilibrium was maintained throughout
Explanation
Soot-darkened bark reduced predation on dark moths, increasing dark allele frequency. The Clean Air Act lightened bark, reversing the selective advantage and lowering dark allele frequency.