Explain Darwin’s theory of Natural Selection with industrial melanism as an experimental proof.

Industrial melanism was an experimental verification for natural selection.
* It was conducted by a British ecologist Bernard Kettlewell on peppered moth Biston betularia.
* These moths were in two colours, grey and black.
* Before industrial revolution, grey moths were abundant because dark moths on light barks of
the trees were easily identified and eaten by birds.
* During industrial revolution the tree barks became dark. Black forms increased in industrial cities like Birmingham due to the increase of pollution.
* Grey moths on the dark bark were easily identified and eaten more by birds.
* Nature offered ‘positive selection pressure’ to light forms before industrial revolution and dark forms after industrial revolution.