Question

Explain natural selection with the example of industrial melanism.

Answer 1

Industrial melanism is one of the best examples of natural selection.

In Great Britain, before industrialization (1845) grey white winged moths (Biston betularia) were more in number than black-winged moth (Biston carbonaria).

These moths are nocturnal and during day time they rest on a tree trunks. The white winged moth can camouflaged (hide in the background) well with the lichen-covered trees that helped them to escape from the predatory birds.

On other hand, the black-winged moth resting on lichen covered tree trunks were easy victims for the predatory birds and their number was reduced. During industrial revolution, large number of industries came up in Great Britain. The industries released black sooty smoke that covered and killed the lichens growing on trees and turn the tree black due to pollution. This change become an advantage to the black-winged moth that camouflaged well with the black tree trunks and their number increased while the white-winged moth become victim to predatory birds due to which their number reduced. Thus natural selection has resulted in the establishment of phenotypic traits in changing the environmental conditions.