Charles Darwin and the Galapagos

Charles Darwin
How did the plants and animals get to the islands?
Natural Selection
A Case Study: Darwin's Finches

In 1831, Charles Darwin sailed to the Galapagos Islands in the HMS Beagle. The captain of the Beagle was Captain Robert Fitzroy, an illegitimate descendent of King Charles II.

Charles Darwin was only twenty when he left Englad in 1831. Thirty years later he published his theory of evolution, unquestionable one of the most revolutionary ideas science has ever known.

Because of Charles Darwin's "discovery" of these islands, much attention has been paid to them and many fascinating things have been discovered.

One of the main questions was how so many different plants and animals arrived on the islands in the first place.

The periodically changing currents have allowed many different species to immigrate to the islands. Some, such as sea lions, fur seals, and penguins, could swim with the help of the currents and giant tortoises are known to float and could have been carried by the same currents.

Also, during the rainy season, rafts of vegetation break off and float out to sea. Most of the reptiles, the only terrestrial mammals (the rice rats), and insects must have arrived by this route.

The light spores of many lower plants could have arrived in the islands by wind along with some vascular plants with lighter seeds. Spiders, small insects, and tiny land snails are frequently transported by wind as well. Land birds and bats, weak fliers, would have to have been blown to the islands, although the seabirds would easily have flown there.

The birds would often aid plants by ingesting seeds before takeoff and then expelling them at their destination. Other seeds, with tiny hooks, could have attached to feathers and feet and been given a free ride. Still other seeds, caked in mud and clinging to a bird's feet or feathers would have been transported there as well.

Darwin is generally credited with the theory of evolution by natural selection. Natural selection is that the strongest survive and propagate and therefore increase the strength of the species.

Once on the islands, the various species established themselves and determined territories. Evolution then set in and many unique species, such as Darwin's finches, resulted.

These finches probably descended from one type of ancestor and then, due to isolation and through chance, different climates and natural forces such as food availability and type, they evolved into thirteen different types of finches.

The process of their evolution would probably have begun with immigrants from the mainland. As they dispersed to different islands, new populations would be formed. Every time these satellite populations dispersed, there would be greater difference between the individual species.

Melissa D. Binde [ ]