When Charles Darwin began writing about the Voyage of the Beagle he began to develop his theory of evolution. He and an associate identified thirteen species of finch on the Galapagos Islands that evolved from a single mainland species. . Because of the different shapes of their beaks, he reasoned that differences in food availability and isolation caused the changes between the species.
The Amblyrhynchus is related to the mainland iguana but much larger. There are two different species in the Galapagos Islands. One of these species is the aquatic species, which although it ventures hundreds of yards out on the water, never strays further inland than a few yards from the rocky shoreline. It is perfectly adapted for life in the water with webbed feet and a broad flat tail. It eats Ulvae seaweed. . The terrestrial version is smaller with a round tail and toes with no webs. It lives only in the central part of the archipelago. . They eat only plants and, instead of drinking water get the liquid they need from cactus plants.
When Darwin discovered the giant tortoises, he thought they were all one species. We now know that there are many different species of Galapagos Tortoise. On each island, the tortoises are different, varying in size and shell shape. They all enjoy a similar diet of vegetation. They also have the same capacity to go long times without water, then go down and fill up completely, storing the water in special sacs in their bodies. In “The Voyage of the Beagle” Charles Darwin remarked “these islands are not so remarkable for the number of the species of reptiles, as for that of the individuals, .
Works Cited
Darwin, Charles. "The Voyage of the Beagle." 1839. The Gutenberg Project. 17 06 2012
