Evolution (AQA GCSE Biology): Revision Note

Evolution

• Evolution can be defined as:

a change in the inherited characteristics of a population over time

• Evolution occurs by a process known as natural selection

  • During natural selection: there is variation between members of the species (arising from mutation); the individuals that are better adapted to their environment are more likely to survive and reproduce; they pass on their favourable alleles to their offspring; this is repeated over many generations

• The theory of evolution by natural selection states that all species of living things have evolved from simple life forms that first developed more than three billion years ago

• Natural selection can lead to the development of new species by a process known as speciation

  • Speciation is said to have occurred when two populations have phenotypes that are so different that they can no longer breed together to produce fertile offspring

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