How did industrial melanism in the peppered moth demonstrate the strength of natural selection?

The phenomenon of industrial melanism in the peppered moth is a classic example of natural selection in action, particularly in response to environmental change. In this case, the dark-colored allele of the peppered moth increased rapidly in frequency during the Industrial Revolution. As pollution darkened the trees and soot covered the surfaces in urban areas, the lighter-colored moths became more visible to predators against this darker background. This resulted in a selective pressure favoring the darker moths, as they were better camouflaged and thus less likely to be eaten by birds.

The rapid increase in the frequency of the dark-colored allele demonstrates the power of natural selection: it not only reveals that the trait conferred a survival advantage in a changed environment but also shows how quickly allele frequencies can change in a population in response to selection pressures. After environmental changes, such as the reduction of pollution and the return of lighter tree bark, a reversal in the frequency of these color variations occurred, providing further evidence of the adaptive nature of the species.

In summary, the interaction between environmental change and the resulting selective pressures led to observable shifts in allele frequencies among the peppered moth population, exemplifying the strength and rapid impacts of natural selection.