evolution

• Evolution


  A gradual change in the inherited traits of an organism over time
• why does Evolution occur

  • Occurs due to natural selection
• Theory of natural selection

  1. Genetic variation exists due to spontaneous mutations

  2. Selection pressures (e.g. competition, disease) exist

  3. Random mutation gives an organism a selective advantage

  4. Organism is better adapted to the environment and survives

  5. Organism reproduces, passing on its beneficial alleles

  6. Frequency of advantageous alleles increase
• Antibiotic resistance in bacteria as an example of evolution

  1. Genetic variation exists due to spontaneous mutations

  2. Antibiotics act as a selection pressure

  3. Mutations gives a bacterium antibiotic-resistance

  4. If an antibiotic is administered, the bacterium is better adapted and survives, whilst other bacteria are killed

  5. Bacterium reproduces, passing on its resistant variant

  6. Frequency of antibiotic-resistant allele increases
• Antibiotic resistance in bacteria as a study for evolution

  Bacteria reproduce very rapidly, allowing the first-hand observation of evolution
• Fossils as evidence for evolution

  • Older fossils (found in rocks deeper in the ground) contain simpler organisms. Newer fossils (found closer to the surface) contain more complex organisms. Comparisons of fossils show that simple organisms evolved into more complex life forms.
• Impact of the theory of evolution by natural selection

  • Enables the classification of organisms into taxa
  • Influences modern medicine by emphasising the importance of finishing antibiotic treatments and the need for the constant production of new antibiotics
  • Highlights the importance of high genetic diversity in habitats which aids conservation projects