GCSE Biology (CCEA)

Topic Summaries

Evolution and natural selection

Evolution

  • 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.
  • Evolution is a change in the inherited characteristics of a population over time through a process called natural selection.
  • Natural selection of variants in a population gives rise to phenotypes best suited to their environment and may result in the formation of new species.
  • If two populations of a species become so different from each other in phenotype that they can no longer interbreed to produce fertile offspring, they have formed two new species.

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