Variation & Evolution

• Evolution- the gradual change in the inherited traits within a population over time. Occurs due to natural selection.
• The phenotype of an organism depends to;

  • Genes
  • Environment
• Genetic variation by random mutations in DNA;

  • There is a change in the DNA sequence so different protein is made.
  • However, most of these changes don't have any actual affect, so doesn't change the organisms phenotype.
  • Alternatively, if the protein change has an affect, then it causes a change in the phenotype, which is usually something bad.
  • But if it isn't and is beneficial. Then, the organism is more likely to survive and reproduce. As a result, of this these beneficial traits are passed onto a offspring.
• Variation - the different characteristics of organisms within a population.
• Mutation - a change in the DNA code.
• Natural selection - the process by which the beneficial traits are passed on by alleles from generation to generation, and gradually they increase in the population over time.
• Evolution occurring due to natural selection;

  1. Random mutation occurs, which causes variation between organisms.
  2. If this mutation is beneficial then the organism is more likely to survive and reproduce.
  3. This means that the mutation is passed onto offspring through genes.
  4. Over many generations, the frequency of the mutation will increase within the population.