The dark color in peppered moths is primarily due to a genetic mutation that affects their pigmentation. This change, known as industrial melanism, became prominent during the Industrial Revolution when pollution darkened tree bark, providing better camouflage for these moths against predators.

What Causes the Dark Color in Peppered Moths?

Peppered moths, scientifically known as Biston betularia, exhibit a fascinating example of natural selection. The dark color, or melanism, in these moths is caused by a specific genetic mutation. This mutation affects the moths’ pigmentation, resulting in a darker appearance. During the Industrial Revolution, soot and pollution from factories darkened the trees and buildings in urban areas. This environmental change provided a survival advantage to the darker moths, as they were better camouflaged against predators like birds.

How Does Industrial Melanism Work?

Industrial melanism is a classic example of natural selection in action. Here’s how it works:

• Environmental Change: As pollution increased during the Industrial Revolution, tree bark became darker due to soot deposition.
• Mutation and Variation: A genetic mutation led to the development of darker-colored moths, known as melanistic forms.
• Survival Advantage: The darker moths were less visible to predators on soot-darkened surfaces, increasing their chances of survival and reproduction.
• Population Shift: Over time, the frequency of the dark-colored moths increased in polluted areas, demonstrating a shift in population dynamics.

The Role of Genetics in Melanism

The genetic basis of melanism in peppered moths involves a mutation in a specific gene responsible for pigmentation. This mutation results in the production of more melanin, the pigment that gives the moths their dark coloration. The mutation is heritable, meaning it can be passed from one generation to the next, allowing the trait to spread through the population under selective pressure.

Historical Context: The Industrial Revolution

The Industrial Revolution, spanning from the late 18th to the 19th century, was a period of significant industrial growth and urbanization. Factories and coal-burning processes released large amounts of soot into the atmosphere, which settled on trees and buildings. This environmental shift had profound effects on many species, including the peppered moth.

• Pre-Industrial Era: Light-colored moths were more common as they blended well with the lichen-covered trees.
• Post-Industrial Era: As pollution increased and lichens died off, the darker moths gained a camouflage advantage.

Reversal of Melanism

Interestingly, as environmental regulations improved and pollution levels decreased, the prevalence of dark-colored moths began to decline. In cleaner environments, lighter-colored moths once again had the advantage, illustrating the dynamic nature of natural selection.

People Also Ask

Why Did Peppered Moths Change Color?

Peppered moths changed color due to a genetic mutation that provided a survival advantage in polluted environments. The darker coloration allowed them to blend into soot-covered surfaces, reducing predation.

What Is Industrial Melanism?

Industrial melanism is a phenomenon where darker-colored individuals of a species become more common in industrial areas due to environmental changes, such as pollution, that provide them with a camouflage advantage.

How Did the Industrial Revolution Affect Peppered Moths?

The Industrial Revolution led to increased pollution, which darkened tree bark and other surfaces. This environmental change favored darker-colored moths, allowing them to survive and reproduce more successfully than their lighter counterparts.

Are There Other Examples of Industrial Melanism?

Yes, industrial melanism has been observed in other species, such as certain butterflies and beetles, where darker forms have a survival advantage in polluted environments.

How Is Melanism Studied in Modern Times?

Modern studies of melanism involve genetic analysis to understand the mutations responsible for color changes. Researchers also use historical data and environmental records to study the effects of pollution on species like the peppered moth.

Conclusion

The dark color in peppered moths is a compelling example of how species adapt to environmental changes through natural selection. This phenomenon, known as industrial melanism, illustrates the intricate relationship between genetics and the environment. As pollution levels have decreased, the balance has shifted back in favor of lighter-colored moths, highlighting the ongoing impact of environmental policies on natural selection. For those interested in evolutionary biology, the story of the peppered moth offers a fascinating glimpse into the mechanisms of adaptation and survival.