1. The Peppered Moth

2. Biston betularia betularia

3. carbonaria

4. Natural selection
Microevolution: change in allele frequency in a population

5. Industrial Revolution caused tree trunks to be black from soot
By 1895, 98% of population of Peppered Moths near Manchester were black
Differential bird predation is thought to be the agent responsible
1950s: Kettlewell’s predation and mark/release/recapture experiments gave positive results.

6. Following anti-pollution laws, carbonaria (the black variety) began to decline on both sides of the Atlantic
This was because the tree trunks were now paler and the black moth was easier to see
The pale moth numbers now increased
The agent of natural selection was the colour of the tree bark
As this changed from white to black and back again, the black and white varieties became more or less obvious.

7. Defined as changes in heritable material (i.e. genes) through time.
Biological evolution
Defined as changes in heritable material (i.e. genes) through time.
Changes in the frequency of the carbonaria gene provides irrefutable proof of biological evolution

8. Kettlewell’s barrel experiments