Evolution and natural selection

• Charles Darwin was a famous English naturalist. During his life he came up with the theory of natural selection and how this drives evolution of new species
• Darwin is associated with the term 'survival of the fittest' which describes how natural selection works.
• individual organisms in an environment are 'selected for'
• 1. Within a population of a species there is a lot of genetic variation. this mix that there is a big mix of different alleles present in the population.
• 2. different alleles can arise when a random mutation takes place. these mutations further increase the variation within the species.
• 3. All organisms within a species are in competition with each other. they are competing for the resources that they need to survive.
• 4. some of the organisms will be better adapted due to the alleles that they have. they have an advantage over the other members of the species. this means that they have a better chance at surviving and reproducing.
• 5. the better adapted organisms are more likely to pass on their alleles. this means that a greater proportion of the individuals in the next generation will inherit the advantageous alleles. the frequency of this allele will increase in the population
• 6. over many generations, the characteristics that led to survival become more common in the population. we say that the ' best characteristics' have been 'naturally selected' and the species have become better adapted to their environment.