Directional selection in peppered moths (Biston betularia) in England

2 phenotypes: black moth, mottle white moth

Prior to 1600 (Industrial revolution)

black form approximately 1%

white form approximately 99%

After 1600 (widespread industrial pollution, smoke and soot)

black form approximately 90%

white form approximately 10%

Now (local pollution from smokestacks)

Near pollution source Away

black form 50% 10%

white form 50% 90%

Outbreeding depression?

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