Evolution

• There must be competition for resources
• The best adapted organisms survived and reproduced,

  whereas those less suited would die
• This gave rise to the phrase ‘survival of the fittest’
• The theory of evolution states that all species of living things have evolved from simple life forms that first developed over 3 billion years ago.
• Darwin first proposed the theory of evolution through natural

  selection by suggesting that only the best adapted individuals

  survive and reproduce, passing on their characteristics to

  their offspring.

  Over several generations,
• In order for evolution to take place, there must be variation in

  the population. Where does the variation come from?
• Mutations can cause variation in a population.

  Mutations are changes in DNA and they occur all the time.

  Very rarely, a mutation will lead to a new phenotype.

  If the new phenotype is suited to an environmental change, it

  can lead to a relatively rapid change in the species.
• Mutations cause variation. The best adapted (fittest)

  organisms survive, reproduce and pass on their genes to their

  offspring. Over several generation, this leads to evolution

  through natural selection.
• If two populations of a species become so different they can

  no longer interbreed to form fertile offspring, they have

  formed two new species (speciation).