[Campbell Biology P.64] Based on the principles of natural selection illustrated in Figure ... | Practice Question

Based on the principles of natural selection illustrated in Figure 1.18, if the soil gradually becomes lighter over time, which of the following is the most likely outcome for the beetle population?

  • A: The population of lighter-colored beetles will decrease, while darker-colored beetles will increase.
  • B: The population of darker-colored beetles will decrease, while lighter-colored beetles will increase.
  • C: Both light and dark beetle populations will decrease due to increased predation.
  • D: The beetle population will show no significant change in coloration.

Explanation

As the soil becomes lighter, the lighter-colored beetles would become less conspicuous to predators birds , giving them a survival advantage. Conversely, the darker-colored beetles would become more visible and thus more vulnerable to predation. Over time, this selective pressure would lead to an increase in the frequency of lighter-colored beetles and a decrease in darker-colored beetles in the population, exemplifying natural selection.