The peppered moth provides a well-known example of natural selection. The light-colored form of the moth was predominant in England before the Industrial Revolution. In the mid-19th century, a dark-colored form appeared. The difference is produced by a dominant allele of one gene. By about 1900, approximately 90% of the moths around industrial areas were dark colored, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the soot-darkened background in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the landscape, and the dark-colored moths have been disappearing. Should the two forms of moths be considered separate species?

Question

Biology

Margaret Norman

5 October, 11:32

The peppered moth provides a well-known example of natural selection. The light-colored form of the moth was predominant in England before the Industrial Revolution. In the mid-19th century, a dark-colored form appeared. The difference is produced by a dominant allele of one gene. By about 1900, approximately 90% of the moths around industrial areas were dark colored, whereas light-colored moths were still abundant elsewhere. Apparently, birds could readily find the light moths against the soot-darkened background in industrial areas and, therefore, were eating more light moths. Recently, use of cleaner fuels has greatly reduced soot in the landscape, and the dark-colored moths have been disappearing. Should the two forms of moths be considered separate species?

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Adan Walker · Answer 1

The answer is no, they are just two varieties of the same species adapted to different environment.

The change in moth color was caused by natural selection which favored the color more suitable for a certain conditions. Thus, in dark background, dark-colored moths could camouflage and escape from the predator (birds). So their chances for the survival and reproduction were higher than those of light-colored moths. When the pollution was reduced, the light colored moths were beneficial for survival.

So, the conclusion is that changes in the environment caused changes in the characteristics that were most beneficial for survival.