Question

A population of beetles is composed of three color variants: dark, light, and medium tan colored beetles. Initially, the beetles inhabit a field environment in which the vegetation is mostly a medium tan color.
This environment is favorable for the medium tan colored beetles as it masks them from their predators, making it difficult for them to be preyed upon.
After the turn of the 20th century, a paper mill is built at the edge of the field that produces a great deal of pollution, causing the surrounding environment to become darker in color.
Which of the following diagrams illustrates the change in the population that occurs after the paper best mill was built?

• A. Diagram 1
• B. Diagram 2
• C. Diagram 3
• D. Diagram 4
• E. None of the diagrams indicate the change in the population that occurs.

Answer 1

The correct option is A Diagram 1

This shows a case of natural selection where dark coloured beetles predominated over medium tan colored beetles. According to Darwin's concept of natural selection, as a struggle for existence, only those organisms could survive which have favourable variation to adapt with the environmental conditions. In other words, struggle for existence results in survival of the fittest which means that natural selection tends to favour those organisms which are most fit to survive with the reproductive age in a particular environment and to produce offspring.

Hence, as the pollution increased due to the setup of paper mill, dark coloured beetles predominated because this feature makes them unnoticed to the predator while the light colored and medium tan colored are vulnerable to the predator.

So, diagram 1 shows how the dark colored beetles predominated over light colored beetles.

So, the correct answer is 'Diagram 1'.