Question

The evolution of the peppered moth over the last two hundred years has been studied in detail. Originally, the vast majority of peppered moths had light colouration, which effectively camouflaged them against the light-coloured trees and lichens upon which they rested. However, due to widespread pollution during the Industrial Revolution in England, many of the lichens died out, and the trees which peppered moths rested on became blackened by soot, causing most of the light- coloured moths to die off due to predation. At the same time, the dark-coloured moths flourished because of their ability to hide on the darkened trees. Since then, with improved environmental standards, light-colored peppered moths have again become common, but the dramatic change in the peppered moth's population has remained a subject of much interest and study Which type of selection is illustrated by the peppered moth's during the Industrial Revolution?

Answer 1

Answer:

Directional selection

Explanation:

The phenotype of individuals and the environment where they live, interact and determines the genes´ destiny in space and time. The result of this interaction and the gene destiny is Natural Selection. Natural selection selects beneficial alleles and increases their frequency in the population.

Among the different types of natural selection, we can find "directional selection".    

Directional selection increases in the proportion of individuals with an extreme phenotypic trait, in this case, dark moths color. This selection presents more frequently in those cases in which interactions between living organisms and the environment modify in the same direction.

In the exposed example, the moth population must be adapted to its environment. The coloration is related to survival strategies. In the beginning, they expressed light coloration useful to camouflage and to avoid predators while resting on their lighted-substrate (lichens and light-colored trees). After the severe environmental impact of the Industrial Revolution, the environment changed. This change acted as a selective pressure. Lichens died, and trees became darker. Light moths were exposed and died after predation. Probably at one point of the evolution, the gene for color mutated, and dark-colored moths appeared. By natural selection, the mutation got fixed. This example reflects directional selection because the population turned from light color to dark color.

In the attached files you will find two graphs expressing directional selection.