The collection of certain moths after industrialisation in England (1920), showed population of light winged less than that of dark winged moths, which was reverse of the observation made prior to industrialisation (1850s). Explain the observation made, with reference to Darwinian natural selection.

This is the case of Industrial melanism. Before industrialisation there was low levels of pollution thus the number of light winged moths was more than dark winged moths as they could easily camouflage with the surrounding.

But after industrialisation as pollution increased the number of dark winged moths increased and the number of light winged moths decreased as due to pollution light winged moths were easily detectable by the predators and the dark winged moths could easily camouflage.

Thus Natural Selection i.e. “The Survival Of The Fittest” was observed.