Natural selection

• Individuals with characteristics most suited to their environment are more likely to survive and reproduce. This is commonly known as 'survival of the fittest'. 
• The genes that allow these individuals to be successful within their environment are passed on to their offspring, which results in these specific genes becoming more common.
• • Individuals in a species show a wide range of variation and this variation is because of differences in their genes.
• • Those that are poorly adapted to their environment are less likely to survive and reproduce. Their genes are less likely to be passed on to the next generation.
• • If two populations of one species become increasingly different in phenotype that they can no longer interbreed to form fertile offspring, this can result in the formation of two species.