Question

Industrial melanism is one of the best example for

• A. Natural selection
• B. Artificial selection
• C. Genetic drift
• D. Gene flow

Hint:

Key Exam Tip:
Industrial melanism is a prime example of how environmental changes can drive adaptive evolution through natural selection, specifically in response to predation pressure influenced by pollution.

Answer 1

The Correct Option is A

Industrial melanism is a classic example that illustrates the process of natural selection. It refers to the increased frequency of melanic (darkly colored) forms of species, particularly insects, in areas affected by industrial pollution. Before the industrial revolution, lighter-colored moths were better camouflaged against lichen-covered trees, making them less susceptible to predation. With industrial pollution, soot killed the lichens and darkened the tree bark. This environmental change favored the survival of darker moths, as they could now blend in better with the darkened environment, leading to an increase in their population. This shift in population characteristics due to differential survival and reproduction based on environmental pressures is a direct demonstration of natural selection.

Step 1: Define industrial melanism. Industrial melanism is the phenomenon where dark-colored (melanic) individuals of a species become more common in polluted environments.

Step 2: Identify the underlying evolutionary mechanism. The change in the frequency of melanic forms is due to differential survival and reproduction in response to environmental changes caused by industrial pollution.

Step 3: Analyze the options in the context of industrial melanism.
• Natural selection: This is the process where organisms with traits better suited to their environment tend to survive and reproduce more offspring, passing on those advantageous traits. In industrial melanism, the dark coloration provides a survival advantage in polluted areas.
• Artificial selection: This involves humans intentionally selecting and breeding organisms for desired traits. This is not the case in industrial melanism.
• Genetic drift: This is random fluctuations in allele frequencies, more prominent in small populations. While genetic drift can occur, the widespread and directional change seen in industrial melanism is primarily driven by selection.
• Gene flow: This is the transfer of genetic material from one population to another. While gene flow can influence allele frequencies, it doesn't explain the specific adaptive advantage and directional change observed.

Step 4: Conclude the best explanation for industrial melanism. The selective pressure exerted by the changing environment (due to pollution) on the moth's camouflage directly leads to the increased survival and reproduction of melanic individuals. This is the hallmark of natural selection. Final Answer: \(\boxed{\text{Natural selection}}\)