What is Natural Selection?

Natural Selection is the accepted theory of evolution first postulated by Charles Darwin and can be thought of as 'survival of the fittest'. It is the process by which a species gradually evolves through time. 

How does it work?

- All organisms within a species show variation between each other due to differences in their genes. 

- Only those characteristics coded for in an organisms genes can be passed on to their offspring. Variation caused by the environment cannot be inherited. 

- Those individuals with characteristics that make them more suited to the environment ( e.g. a finch with a beak shape better suited to eating the food available) will be more likely to survive and reproduce. These genes coding for the successful characteristic are then passed onto their offspring.

- Those individuals with characteristics poorly adapted to the environment are less likely to survive and reproduce. Therefore their genes are less likely to be passed to offspring. 

- As these advantageous genes accumulate throughout the generations, a species gradually evolves.