Directional selection is a type of natural selection that occurs when a specific phenotype یا trait in a population is favored, leading to a change in the population's allele frequencies over time. In directional selection, individuals with traits at one extreme of the phenotypic range are more likely to survive and reproduce than those at the other extreme.
This process can occur due to environmental changes, competition, or other factors that make certain traits more advantageous in a given context. Over successive generations, this can result in a shift in the population's traits toward the favored extreme. A classic example of directional selection is the evolution of the peppered moth in England, where darker moths became more common during the Industrial Revolution due to increased pollution darkening the trees on which they rested, making them less visible to predators.