During the Industrial Revolution, explain what caused the population of light-colored peppered moths to decrease and the population of dark-colored peppered moths to increase over time. Be sure to include how the ability to survive and reproduce impacts the process of natural selection.
During the Industrial Revolution, the population of light-colored peppered moths decreased, and the population of dark-colored peppered moths increased over time due to the phenomenon known as industrial melanism. Prior to the Industrial Revolution, the moths' light coloration provided them with effective camouflage against the light-colored lichen-covered trees they rested on during the day. This gave them a survival advantage as they remained undetected by predators, predominantly birds.
However, with the onset of industrialization, factories began emitting large amounts of pollution, primarily in the form of soot, which blackened the tree trunks and surrounding environment. As a result, the lichen-covered trees became darkened, making the light-colored moths stand out and become more noticeable to predators. In contrast, the dark-colored moths had a significantly better chance of blending into the blackened environment, giving them a survival advantage.
Natural selection played a crucial role in this process. As the environment changed, birds preyed more heavily on the light-colored moths that were now more visible against the darkened background. Consequently, these light-colored moths had a lower chance of surviving to reproductive age and passing on their genes. On the other hand, the dark-colored moths had a higher chance of surviving and reproducing due to their improved camouflage, increasing the proportion of dark-colored moths in subsequent generations.
Over time, the process of natural selection favored the individuals with traits that increased their chances of survival and reproduction in the changed environment. Through this mechanism, the population of light-colored peppered moths decreased, while the population of dark-colored peppered moths increased. This is a classic example of evolutionary adaptation driven by natural selection, demonstrating how the ability to survive and reproduce impacts the traits and population dynamics of a species.