Question

Darwin believed that the various species of finches on the Galapagos islands came from one common ancestor.he believed they evolved by what?

Answer 1

adaptive radiation 

(the diversification of a group of organisms into forms filling different ecological niches)

Answer 2

He believed they evolved because of he food source. Whether the food was on a tree so they must have long necks or if the food was on the ground, therefore they did not need long necks.