Gálapagos Islands and Darwin’s Theory of Evolution

Abstract

The Galapagos Islands are closely associated with Darwin’s name because the animals and plants living on these islands provided clues to Darwin to formulate his theory of evolution by means of natural selection. Galapagos is a group of 19 volcanic, Pacific islands on the equator, about 1000 km west of Ecuador of South America. Being volcanic, there was no life on them when they were formed; all organisms presently living on the islands are the descendants of those that came from the South American mainland. Darwin visited these islands in 1835 during his voyage around the world in HMS Beagle and stayed for five weeks, studying and collecting plants, animals, and rock samples from the islands. His detailed studies of the collections upon his return to London, particularly on tortoises, mockingbirds, and finches, revealed that all these species living on the Galapagos were endemic to the island and did not occur anywhere else in the world, but all of them closely resembled the species present on the South American mainland. This realization made him speculate that the Galapagos inhabitants, after they arrived from the mainland, evolved into different species over the years, shaped by the environment of the islands. He visualized evolutionary changes as a result of the competition amongst individuals under changed environmental conditions, which acted as a selective agent. Under such selection, those individuals possessing favorable variations survived and reproduced, passing on their variations to their offspring, and those without them were eliminated. Over the years, the concept of evolution has become one of the most important, powerful and unifying concepts in biology.