Competition & Adaptation: Moth Evolution Simplified

In the forests of Britain before the Industrial Revolution, the peppered moth existed in two distinct color variations.The light-colored peppered moth was the dominant form, characterized by white wings covered in black speckles.These moths were incredibly successful because their coloring provided perfect camouflage against the pale, lichen-covered tree bark where they rested during daylight hours.In contrast, the dark-colored variation of the moth was quite rare.Dark moths stood out against the light bark, making them easy targets for bird predators.As a result of this selective pressure, light moths made up about ninety-five percent of the population, while dark moths were only about five percent.This natural balance would soon face a dramatic change with the arrival of the Industrial Revolution.During the Industrial Revolution of the 1800s, factories began spreading across Britain.These factories released enormous amounts of soot and pollution into the air.The pollution had a dramatic effect on the environment. Tree bark, once light colored due to lichens, became blackened with soot.Initially, light-colored moths were abundant, while dark moths were rare.Against the newly darkened trees, light-colored moths became highly visible to predators.Dark moths, now better camouflaged, survived and reproduced more successfully.Over several decades, this led to a dramatic shift in moth populations. Dark moths became increasingly common, while light moths declined significantly.This remarkable shift in moth populations demonstrated the power of natural selection in response to environmental change.As we entered the 1950s, new air quality laws began to change the environment.Trees gradually returned to their natural light color as pollution decreased.This environmental change triggered a shift in moth populations.Light-colored moths began to regain their advantage, while dark moth populations declined.This remarkable example demonstrates natural selection in action.First, environmental changes create new conditions. Then, certain traits provide survival advantages. Successful survivors reproduce more frequently, leading to population shifts over time.Today, moth populations vary based on local environmental conditions.Rural areas with cleaner air tend to have more light moths, while urban areas still maintain higher populations of dark moths.This ongoing adaptation shows how species continue to evolve in response to their changing environment.