Survival of the fittest!

“Tortoises or land turtles are land-dwelling reptiles of the family of Testudinidae, order Testudines. Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise has both an endoskeleton and an exoskeleton. Tortoises can vary in size from a few centimeters to two meters. Tortoises tend to be diurnal animals with tendencies to be crepuscular depending on the ambient temperatures. They are generally reclusive animals. The biggest operational difference between tortoises and turtles is that tortoises are unable to swim; indeed, they cannot float, whereas turtles can” (www.answers.yahoo.com/question/index?qid=20080409144910AAbkGR8&show=7, retrieved 4/19/2008).
“The Galápagos tortoise (or Galápagos giant tortoise), is the largest living tortoise, endemic to nine islands of the Galápagos archipelago. Adults of large subspecies can weigh over 300 kilograms (660lb) and measure 1.2 meters (4 ft) long. Although the maximum life expectancy of a wild tortoise is unknown, the average life expectancy is estimated to be 150-200 years. The Galápagos tortoises have very large shells (carapace) made of bone which is an integral part of the skeleton. The bony plates of the shell are fused with the ribs and other bones to form a rigid protective structure. When a tortoise feels threatened it can withdraw its head, neck and forelimbs into its shell for protection, presenting a thick shield to a would-be predator. The legs have hard scales that provide an effective armor when withdrawn” (www.wikipedia.org/wiki/Gal%C3%A1pagos_tortoise, retrieved 4/19/2008).

“In the 19th century, Charles Darwin, a biologist from England, set off on the ship HMS Beagle to investigate species of the Galapagos Islands. After spending time on the islands, he soon developed a theory that would contradict the creation of man and imply that all species derived from common ancestors through a process called natural selection. Natural selection is considered to be the biggest factor resulting in the diversity of species and their genomes. One of the prime motives for all species is to reproduce and survive, passing on the genetic information of the species from generation to generation. When species do this they tend to produce more offspring than the environment can support. The lack of resources to nourish these individuals places pressure on the size of the species population, and the lack of resources means increased competition and as a consequence, some organisms will not survive. The organisms that die as a consequence of this competition are not totally randomly. Darwin found that those organisms more suited to their environment were more likely to survive. This resulted in the well known phrase ‘survival of the fittest’, where the organisms most suited to their environment had more chance of survival if the species falls upon hard times. Those organisms who are better suited to their environment exhibit desirable characteristics, which is a consequence of their genome being more suitable to begin with. This 'weeding out' of less suited organisms and the reward of survival to those better suited led Darwin to deduce that organisms had evolved over time, where the most desirable characteristics of a species are favored and those organisms who exhibit them survive to pass their genes on. As a consequence of this, a changing environment would mean different characteristics would be favorable in a changing environment. Darwin believed that organisms had 'evolved' to suit their environments, and occupy an ecological niche where they would be best suited to their environment and therefore have the best chance of survival. As the above indicates, those alleles of a species that are favored in the environment will become more frequent in the genomes of the species, due to the organisms higher likeliness of surviving as part of the species at large” (http://www.msnbc.msn.com/id/8727984/-storyContinued, retrieved 4/20/2008).