biologyperformancetask: evolution 07: MAIN IDEAS of Darwin's theory

Darwin's Theory of Evolution

Darwin's Theory of Evolution briefly summarized are:

1. Variation: There is variation in every population

2. Competition: Organisms compete for limited resources

3. Offspring: Organisms produce more offspring that can survive

4. Genetics: Organisms pass genetic traits on to their offspring

5. Natural Selection: Those organisms with the most beneficial traits are more likely to survive and reproduce

Darwin's Theory of Evolution is the widely held idea that all organisms is related and that they descended from a common ancestor. The theory makes the assumption that the development of life from non-life and stresses a purely naturalistic (undirected) "descent with modification". That is, complex creatures evolve from more simplistic ancestors naturally over time. To put it briefly, as random genetic mutations occur within an organism's genetic code, the valuable mutations are kept because they aid survival. This process is known as natural selection. These mutations are passed on to the next generation. Over time, the mutations accumulate and this results in a different organism which is not merely a variation of the original.

Darwin wrote, "…Natural selection acts only by taking advantage of slight successive variations; she can never take a great and sudden leap, but must advance by short and sure, though slow steps."[1] As such, we can say that Darwin's Theory of Evolution is a slow gradual process.

[1] Charles Darwin, "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life," 1859, p. 162.
1) Source: http://www.darwins-theory-of-evolution.com/, 31st march 2007
2) Source: http://www.spaceandmotion.com/Charles-Darwin-Theory-Evolution.htm, 19th April 2007

Darwin's theory: Natural selection [one of the main highlights of the theory]

Ancient Greek philosophers such as Anaximander postulated the development of life from non-life and the evolutionary descent of man from animal. Charles Darwin brought something new to the old philosophy-a probable mechanism called "natural selection." Natural selection means the survival of organisms that are best suited to surviving and reproducing in their environment. The rationale of natural selection is to preserve and accumulate minor advantageous genetic mutations whereby favourable traits that are heritable become more common in successive generations of a population of reproducing organisms, and unfavourable traits that are heritable become less common.

For example, if a member of a species developed a useful advantage (it grew fins and learned to swim). Its offspring would inherit that advantage the advantage would be passed down to future generations. The inferior (disadvantaged) members of the same species would gradually die out, leaving only the superior (advantaged) members of the species. Natural selection is the preservation of a useful advantage that allows a species to compete better in the wild. Basically, natural selection eliminates inferior species gradually over time. Over time, this process, which eliminates inferior species, can result in adaptations that specialize organisms for certain ecological niches and may ultimately result in the emergence of new type of species.

Up till today, natural selection still remains as the single primary explanation for adaptive evolution.

1) Source: http://www.darwins-theory-of-evolution.com/, 31st march 2007

2) Source: http://en.wikipedia.org/wiki/Natural_selection, 19th April 2007