Answer:
He compared two groups of finches to illustrate natural selection.
Explanation:
Darwin traveled to the Galapagos Island and noted that there were different species of finches birds. Some had elongated peaks to be able to eat in areas where the typical vegetation was cacti, other finches had their flat peaks to be able to collect fruits from the ground.
According to his observations, Darwin stated that there must have been a finch ancestor from which each species had evolved, adapting its physiology by natural selection, depending on the characteristics of their diet and the area where they lived.
