Transcript Kettlewell & the Peppered Moth

The Peppered Moth
Example of Evolution
Background Information
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1850’s: Industrial Revolution
Moths (Biston betularia) come in
both light and dark colors.
Until the 1850’s, the dark color was
rare.
After almost 100 years, the darker
color was the dominant form.
Birds are predators of moths
What is happening?
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Hypothesis: Evolution by natural
selection is taking place in peppered
moths.
In polluted areas, dark moths have
higher fitness (blend in with sootcovered trees) than light moths.
In non-polluted areas, light moths
have higher fitness.
What is driving this evolution?
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Selective Pressure: Predators
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Selective Agent: BIRDS!
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Therefore, moths that blend in with
trees have a higher fitness (survive to
reproduce) than those that do not.
The Moths:
Conclusion about the moths:
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Due to natural selection, in
polluted areas darker moths
have a higher fitness.