Saturday, February 19, 2005
Richard Dawkins: Evolutionary Arms Race
Richard Dawkins is in the Galopagos Islands and writes the following from a ship named the Beagle. This excerpt is from the first of three essays to be published in the Guardian. Here Dawkins takes a look at the evolution of the Galopagos most famous residents, the giant tortises.
"The tortoises did something similar (to the finches), evolving distinctive shell shapes on the different islands. The races on the larger islands have high domes. Those on smaller islands have saddle shaped shells with a high-lipped window at the front for the head. The reason for this seems to be that the large islands are wet enough to grow grass, and the tortoises there are grazers. The smaller islands are mostly too dry for grass, and the tortoises resort to browsing on cactuses. The high-lipped saddle shell allows the neck to reach up to the cactuses which, on their side, grow higher in an evolutionary arms race against the browsing tortoises."You can read the whole essay here.