44. Which of the following best illustrates the mechanism of natural selection?
Answer: C
The appearance of pesticide-resistant populations of bedbugs after prolonged use of a pesticide illustrates the mechanism of natural selection.
This scenario exemplifies natural selection as it demonstrates how a population adapts to environmental pressures, specifically through genetic variations that confer resistance to pesticides.
A) The isolation of a group of mainland birds on an island after a major hurricane
This option describes a scenario of geographical isolation but does not directly illustrate natural selection. While isolation can lead to speciation and evolutionary changes over time, it does not demonstrate the immediate process of selection based on advantageous traits within a population.
B) The emigration of half of the members of a population of mice after a large fire
This situation involves a change in population dynamics due to emigration but does not illustrate natural selection. Emigration may alter gene frequencies but does not necessarily indicate that advantageous traits are being selected for or against in the remaining population.
C) The appearance of pesticide-resistant populations of bedbugs after prolonged use of a pesticide
This option clearly illustrates natural selection. It shows that in response to the selective pressure of pesticide use, bedbugs with genetic mutations that confer resistance survive and reproduce, leading to a population increasingly composed of resistant individuals.
D) The death of three members of a population of mountain goats in an avalanche
While this scenario involves mortality, it does not illustrate natural selection effectively. The deaths may be random and do not indicate that any specific traits are being favored or selected against in the population as a whole.
Conclusion
The correct answer, option C, effectively demonstrates natural selection through the emergence of pesticide-resistant bedbugs as a direct response to environmental pressures. The other options fail to show the mechanism of natural selection in action, as they either involve geographical changes, random population shifts, or do not involve advantageous traits being selected.