Q.Explain natural selection with example of industrial melanism.

Natural selection favours whichever heritable variant best suits the current environment.

The peppered moth's colour-frequency shift during Britain's industrial era is the textbook demonstration of natural selection in action.

Natural selection is the process by which individuals with heritable traits better suited to their environment survive and reproduce more successfully than others, causing those advantageous traits to become more frequent in the population over generations, while poorly-suited traits decline. Industrial melanism in the peppered moth (Biston betularia) in England provides a well-documented example. Before the Industrial Revolution, tree trunks in England were covered with pale lichen, and the common light-coloured (typica) form of the moth was well camouflaged against this background, while the rarer dark (melanic, carbonaria) form stood out and was more easily caught and eaten by bird predators — so the light form predominated. As industrial pollution during the 19th century killed the lichen and coated tree bark with soot, turning it dark, the camouflage advantage reversed: now the dark melanic moths blended in with the blackened bark and survived predation better, while the pale moths became conspicuous and were preferentially eaten. As a result, the frequency of the dark form rose sharply in industrial areas over a few dec …