Fragile Inheritance

April 19, 2002


Provided by: NASA Earth Observatory
Summary authors & editors: Susan Howard

On March 12, 2002, the above true-color image of the Galapagos Islands was acquired by the Moderate-resolution Imaging Spectroradiometer (MODIS), on board the Terra satellite. The Galapagos Islands, which belong to Ecuador, straddle the Equator approximately 1,000 km (620 miles) west of South America. Volcanic in origin, the archipelago is less than 5 million years old and includes over 40 islands and islets spread over an area of 7,500 square km (2,895 square miles).

The isolation of the islands is important because it reduced the migration of plants and animals from the mainland so that only a few members of a limited number of species arrived here. These "founding populations" reproduced and eventually spread to other islands in the archipelago where they encountered a variety of environmental conditions. After studying the variations in related plants and animals, the 19th century naturalist Charles Darwin theorized that particular environmental conditions favoured or "selected for" certain physical features, and that over time, the founding populations evolved into the separate species and subspecies now occupying different islands. This process, called "adaptive radiation," is ongoing and more than a century after Darwin (today, Friday, is the 120th anniversary of his death), the unique birds, tortoises, iguanas, plants and other inhabitants of this World Heritage Site continue to inspire evolutionary biologists. Ecuador faces the challenge of balancing the interests of researchers, ecotourists, and the commercial fishing industry while preserving the fragile ecosystems of this geologic and biological treasure.

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