Explain natural selection with suitable example.

Explanation

A group of red beetles live in some bushes with green leaves. Their population will grow by sexual reproduction. Crows are natural predator for beetles.

Colour variation arises during reproduction. One beetle with green colour is formed in the population of red beetles. This beetle passes the changed colour on to its progeny, making progeny beetles green. Crows cannot see green coloured beetles on the leaves of the bushes. Thus progeny of green beetles is not eaten, while the progeny of red beetles continues to fall prey. As a result, more green beetles survive than red ones in the beetle population.
A rare variation became common characteristic in the population. Because it gave a survival advantage. i.e., it was naturally selected. The natural selection is exerted by the crows. The more crows there are, the more red beetles would be eaten and the more the proportion of green beetles would be in the population.
Thus, natural selection is directing evolution in the beetle population. It results in adaptations in the beetle population to fit their environment better.