The Galapagos Islands have often been called a “laboratory of evolution”. There are few places in the world where it has been possible to find such a variety of species, both plant and animal, which shows so many degrees of evolutionary changes, in such a restricted area.
Once organisms reach oceanic islands they are essentially isolated from other land masses. If the islands are distant enough from a source to make colonization a rare event, then they may be thought of as almost independent biological units. Oceanic islands can have species which, though related to mainland forms, have evolved in ways different from their mainland relatives as a result of their isolation in a different environment. This is a key factor in island evolution.
It is not surprising that Charles Darwin was so struck by the life he found on these islands.
Formulated by Darwin, Natural Selection is the process by which propagation becomes change, and species diverge one from another.
A classic example of adaptive radiation in birds, which has served generation of evolutionary biologists, is Darwin’s finches. A total of 13 species evolved within the Galapagos archipelago from a common ancestor whose founding type and source from the American continent have not yet been identified. A single fourteenth species occurs on CocosIsland off of Costa Rica, about five hundred miles northeast of the Galapagos.
That al the finches are closely related, and presumably evolved from the same progenitor stock, is indicated by a complement of characteristics common to all.
The word endemic refers to organisms which are found nowhere else in the world due to the fact that they evolved and remained isolated on a given area and therefore developed unique characteristics. In the Galapagos you will find several species that fall into this classification