AP BIOLOGY

Detailed explanation-1: -In Galapagos he found a remarkable population of plants, birds and reptiles that had developed in isolation from the mainland, but often differed on almost identical islands next door to one another and whose characteristics he could only explain by a gradual transformation of the various species.

Detailed explanation-2: -Darwin noticed that different tortoise species lived on islands with different environments. He realized that the tortoises had traits that allowed them to live in their particular environments. For example, tortoises that ate plants near the ground had rounded shells and shorter necks.

Detailed explanation-3: -Later, Darwin concluded that several birds from one species of finch had probably been blown by storm or otherwise separated to each of the islands from one island or from the mainland. The finches had to adapt to their new environments and food sources. They gradually evolved into different species.