Explain industrial melanism with example?

Industrial melanism. It is an example of natural selection shown by peppered moth Biston betularia. The moth had a dull grey coloured body before industrial revolution in England. The colour of moth enabled it to adapt to the light coloured background. After the industrial revolution the environment changed with the deposition of tar soot on the bark of the trees. As a result, light coloured species of moth were easily detected by the predators against the dark bark of trees while the black coloured moth Biston carbonaria increased in number. The change enabled the animal to adjust with the changed environment.
Thus industrial melanism is an interesting example of evidence in favour of natural selection.

However, with the replacement of coal and petroleum by gas and electricity the situation has changed. Thus the white moth has become abundant with a sharp decline in the number of black. The reason being the decrease in pollution and restoration of grey colour on the trees because of the growth of the lichens on the tree trunk.

Before industrialisation the number of white moth were more because there were no industries, no pollution and hence trees were whiter so the white moths got camouflaged unlike brown winged moths. After industrialisation, pollution increased and the trees trunks became darker and the dark winged mkths were able to camouflage themselves. The predators hence prey white moths and the number of brown winged moths increases more than white moths after industrialisation.