What happened to the peppered moth population by 1900?

Answer 1

By 1900, the peppered moth population had undergone a significant change in response to the environmental conditions in industrial areas of England. Prior to the Industrial Revolution, the majority of peppered moths had light-colored wings, which provided effective camouflage against lichen-covered trees where they rested. However, as coal-burning factories became prevalent and released large amounts of soot and pollutants into the air, the lichen on the trees started dying off, causing the previously well-camouflaged light-colored moths to become more visible to predators.

This change in the environment led to an increase in predation on the light-colored moths, resulting in a decline in their population. On the other hand, a minority of peppered moths had naturally occurring dark-colored wings due to a genetic mutation. These dark-colored moths, which were previously less visible against lichen-covered trees, enjoyed a selective advantage in the newly polluted environments as they were better camouflaged against the soot-covered trees.

As a result, the percentage of dark-colored moths in the population increased significantly by 1900, while the population of light-colored moths decreased. This phenomenon, known as industrial melanism, provided one of the most celebrated examples of natural selection and evolution in action.