Darwin hypothesized that new species could appear gradually through small changes in an ancestral species. which observation that he made about finches most supports that hypothesis?

The beak shapes of the finches on the Galapagos islands differed in shape and size. Finches arrived on the Galapagos islands approximately 2 millions years ago. Darwin noticed that finches on each of the islands were different, resulting in the discovery of 15 distinct kinds of finches. In some cases the beak shapes differed due to the food available on each island, such as large strong beaks for breaking open nuts, while others ate insects. Other differences included body shape, song, and feeding behaviors.