The best illustration of a result of natural selection is giraffes having increasingly longer necks over time.
Natural selection is the process by which living organisms become better adapted to their environment, tend to survive, and produce more offspring over time.
Natural selection occurs spontaneously in organisms and serves as the basis for their survival in their environment. It is referred to as the survival of the fittest.
An example of natural selection is that of giraffes that develop increasingly longer necks over time.