Use evidence from the Grants research to explain how natural selection leads to evolution.

Grant's research on medium sized finches on the Galapagos islands observed evolutionary processes in real time. He has found that the drought has decreased the availability of small and soft seeds that the finches were accustomed to. Since there is a variability in beak size in this finch species, the individuals with larger beaks could feed on bigger and tougher seeds and still manage to survive the drought-induced decrease in food availability. As a direct result of natural selection favoring the big beaked finches, there was an increase in numbers of finches with bigger beaks in the generations after the drought.