CBSE Class 10 Answered

One of the best examples to explain this is:

Initially in England, before the industrial revolution, the tree trunks were not blackened and the lighter colored moths were present in higher frequencies. However, during the period when the number of coal-burning factories in England began increasing it was noticed that the tree trunks became blackened. So the number of melanic individuals of the species of Peppered Moth was becoming more common. Originally rare in the population of normally light-colored moths, the frequency of the melanic form increased in polluted areas until it was over 90%. The change was presumed to be a result of natural selection since the melanic moths in polluted areas better matched the blackened tree trunks where they rested during the day. In unpolluted forests distant from industrial centers the lighter colored moths were present in higher frequencies.

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