Question

Assertion :Industrial melanism of Biston betularia is an example of disruptive natural selection. Reason: The mutation saved their population.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Assertion is incorrect but Reason is correct.

Answer 1

The correct option is D Assertion is incorrect but Reason is correct.

The evolution of the peppered moth (Biston betularia) is an evolutionary instance of colour variation in the moth population as a consequence of Industrial Revolution. Specifically, it is a concept of increase in number of dark-coloured moths due to industrial pollution, and reciprocal decrease of the population under clean environment. Hence, the phenomenon is called industrial melanism. It is a first recorded and experimented case of Charles Darwin's natural selection in action. Light-coloured body was an effective camouflage in clean environment, such as in Dorset; while dark colour was beneficial in polluted environment like in Birmingham. This selective survival was due to birds which easily caught dark moths on clean trees, and white moths on trees darkened with soot. Industrial melanism is an example of directional natural selection. So, assertion is wrong and reason is correct. Thus, option D is correct and other options are wrong.