The Peppered Moth

Biston betularia betularia

carbonaria

Natural selection Microevolution: change in allele frequency in a population

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.

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.

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

Kettlewell’s barrel experiments