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The process of natural selection used to modify the features of a species through generations is known as evolution.

A gene mutation is a permanent change in the DNA sequence that makes up a gene that varies from the sequence present in most people.

Staphylococci infections were rapidly destroyed by tiny dosages of penicillin when it was initially introduced, but the bacterial DNA underwent a mutation at some point, making a specific Staphylococcus resistant to penicillin. Treatment with penicillin killed one of the sensitive Staphylococci, but the resistant bacterium lived and multiplied, resulting in a colony of resistant bacteria. These mutant bacteria enjoyed a survival advantage, not just because they didn't have to fight for space and nutrition with the sensitive bacteria.

Prior to the Industrial Revolution, the light-colored pepper moth was the most common in England; however, during the Industrial Revolution, a dark-colored peppered moth arose, and by 1895, 98 percent of the moths in the industrialised districts of England were dark. During the industrial revolution, coal was the dominant energy source, and the massive rise in its consumption resulted in gigantic black, sooty clouds in and around London and Manchester. These clouds were large enough to obstruct sunlight while also depositing black coal dust on tree bark. Light-colored pepper moths were evidently disadvantaged as a result of the black bark, which made them more visible to birds that preyed on the moths.

It's thought that a mutation occurred at some time, resulting in dark-colored pepper moths, which had an edge in survival since they blended in with the black, soot-stained bark. In this habitat, as well as in and around Manchester, these black moths had a strong survival edge. The dark moth was more difficult for birds to perceive as tree bark got darkened, providing it a survival edge. Dark moths were less likely to be eaten, which meant they had a better chance of reproducing than light ones. By 1895, 98 percent of moths in London and Manchester were dark-colored as a result of this survival advantage.Since then, less coal has been used, resulting in lighter bark and a rise in the number of light-colored moths.

Thus, the evolution and the mutation in DNA has been occurred by using the Staphylococci gene.