Evolution

• what is evolution?

  • gradual change in the inherited characteristics within a population over time
  • occurs due to natural selection which may result in the formation of a new species
• outline the theory of natural selection

  all species of living things have evolved from simple life forms that first developed more than 3 billion years ago

  1. genetic variation exists due to spontaneous mutations
  2. selection pressures 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 increases
• how do two populations become different species?

  when their phenotypes become different to the extent that they no longer interbreed to produce fertile offspring