What is Natural selection?
Charles Darwin in 1859 wrote a book containing ideas referred to as Darwin’s theory of evolution by natural selection. The theory of evolution by natural selection can be summarised, it shows that Darwin believed that natural selection caused evolution:
• Individual characteristics of organisms, such as height, colour and movement are important for its ability to survive. Those individuals with advantageous features have greater chance of survival. This leads on to say that Individuals within a species show variation. Characteristics vary in organisms of the same species and in some are advantageous for that individual and can help it to survive. For example if one adult zebra is faster than another adult zebra due to variation then the faster zebra is more likely to survive and avoid predators. Another good example is a good example of natural selection is before a drought individual birds showed variation in beak depth and length. When the drought happened birds with longer and deeper beaks had an advantage because they were able to obtain food.
• More individuals are produced then can survive. If those characteristics which help the organism to survive are inherited by their offspring then individuals with those characteristics will gradually become more common generation after generation. These organisms will be selected for whereas the ones less well adapted to the environment will correspondingly decrease, that is they will be selected against. In my example before using the beak size variation the birds with the longest beak had the greatest change of surviving therefore the birds who survived produced offspring with long beaks. The alleles for larger beaks would therefore be more prominent in future generations. (This is an example of directional selection which I will explain later)
There has been a lot of scientific research into natural selection since Darwin published his book of evolution on “the origin of...