Charles Darwin's theory of natural selection

Natural selection is one of the most important concepts in biology. Charles Darwin introduced this theory in his book"On the Origin of Species". Basically, natural selection refers to the differential sucess in reproduction of different phenotypes (a phenotype is an observable characteristic or trait) resulting form interacton with the environment.

The main features of Darwin's theory describes how new species formed:

1. Firstly, there is an over production of offspring.
2. Despite this, there remains a constancy of numbers within the community because only a fraction of the population survives.
3. This is due to selection pressures due to the environment. Examples of selection pressures would be the competion for resources and presence of predators.
4. Variation exists within the community due to the presence of different genes wich results in the expressions of different phenotypes.
5. In the wild, it is the survival of the fittest and different phenotypes have different sucess of survival. The evironment selects for individuals with favourable traits .
6. As those that survive, are likely to mate with survivors, their offspring would natuarlly have genes which confer favourable traits.
7. Over thousands of generations, a species will form.


References:

http://en.wikipedia.org/wiki/Natural_selection
http://en.wikipedia.org/wiki/Phenotype
RJC diversity and evolution lecture notes