This graph shows the population size of dark colored moths between 1960 and 2000. Suggest what may happened to cause this change in population size

Answer 1

One possible explanation for the change in population size of dark colored moths between 1960 and 2000 could be the phenomenon known as industrial melanism. This is a term used to describe the increase in the frequency of dark-colored moths in populations that live in urban areas with high levels of pollution.

Prior to the Industrial Revolution, light-colored moths were more common in populations due to their ability to blend in with the lichen-covered tree trunks that dominated the environment. However, with the increase in industrialization and pollution, the lichen on trees died off, making the tree trunks darker. This change in environment provided a selective advantage to the darker moths, as they were better able to blend in and avoid predation by birds.

As a result, the population size of dark colored moths increased over time, while the population size of light colored moths decreased. This change in population size is a classic example of natural selection in action, where organisms with traits that are better suited to their environment are more likely to survive and reproduce.