Which scenario best illustrates the concept of natural selection?

 A scenario that illustrates the concept of natural selection is the one where a population of beetles varies in color from green to brown. Let's imagine a forest where these beetles live, and over time, birds prey on these beetles. The green beetles are more easily spotted against the brown forest floor, making them more likely to be eaten by birds. The brown beetles, on the other hand, are camouflaged and are less likely to be eaten. Over several generations, if the birds continue to eat the green beetles more often, there will be more brown beetles that survive to reproduce. The proportion of brown beetles in the population will increase over time because their coloring provides a survival advantage in the context of the forest environment and predators.

The key steps involved in this process are:

1. Variation: The population of beetles has variation in color.

2. Selection: The green beetles are being selected against because they are preyed upon more often due to their visibility.

3. Reproduction: Brown beetles survive at a higher rate and therefore reproduce more, passing on their genes for brown coloring.

4. Change Over Time: Over generations, the population shifts to being more brown because those individuals are more fit for their environment.

This scenario demonstrates natural selection at work because it shows how inherited traits that confer a survival advantage tend to increase in frequency over time, while disadvantageous traits decrease.