The peppered moth, found in England, Wales, Scotland and Ireland, is one of the most amazing examples of natural selection. First of all, what is natural selection? It is a process where the characteristics of organisms in a population change over time with the means to survive and pass on genes. 

Before the industrial revolution in Britain, most peppered moths looked like this: pale insects with dark spots peppered on the wings, designed to camouflage them against lichen and pale birch trees they rested on.

However, there were some moths that were black. These mutant moths were easily spotted against the trees and eaten by birds or other predators. This meant that fewer black peppered moths survived to breed, so they were less common in the population.

During the industrial revolution, the trees these moths rested on gradually became covered and blackened with soot due to factories burning coal and releasing black smoke, with little government regulation. This meant that the mutant black moths were better camouflaged from predators while the white moths were more vulnerable. Due to this natural selection, the black peppered moths quickly reproduced and passed down their unique colour to their offspring, becoming far more common than the white peppered moths. The first black peppered moth was recorded in Manchester in 1848 and by 1895, 98% of the peppered moths in the city were black. 

It’s important to know that this change in population was not caused because the pollutants from the factories were making the moths darker. The dark peppered moths always existed but at a much lower number compared to the white peppered moths. It was, in fact, the change in their environment that allowed black peppered moths to thrive and pass down their characteristics to the next generations.

Sources:

1. https://www.bbc.co.uk/bitesize/guides/zpp74qt/revision/3

2. https://askabiologist.asu.edu/games-sims/peppered-moths-game/natural-selection.html#:~:text=Tutt%20suggested%20that%20the%20peppered,things%20respond%20to%20natural%20selection.