Final answer:
The darkening of environments due to industrial pollution led to directional selection in populations of the peppered moth, favoring the survival of darker moths, a phenomenon known as industrial melanism.
Step-by-step explanation:
The phenomenon of increased environmental darkness due to industrial activities causing microevolutionary changes in populations of insects, such as the peppered moth (Biston betularia), is named industrial melanism.
Before the Industrial Revolution, light-colored moths could camouflage with their environment and avoid predators. However, with the advent of the Industrial Revolution and the resultant pollution, dark-colored moths became better suited for survival against a backdrop of soot-covered trees.
This change in the moth population from light to dark is a textbook example of directional selection, where environmental pressures lead to a shift in the population's characteristics towards those that offer a survival advantage.