Over a span of two decades in the 1900s, scientists measured changes in the beak size of a population of galápagos ground finches. these data could provide

Evidence of a natural selection in action.

Explanation: Wallace and Darwin both observed similar patterns in other organisms and they independently developed the same explanation for how and why these changes could take place. However, Darwin called this mechanism natural selection. Natural selection, is also known as "survival of the fittest." is more prolific reproduction of indivduals with favorable traits that survive environmental change just because of those traits. This is what leads to evolutionary change. Darwin believed that the finches because the finches had different beak sizes among species that they came from the mainland species.