Evidence for Evolution (AQA GCSE Biology): Revision Note

One very clear piece of evidence for evolution is antibiotic resistance in bacteria

• When an antibiotic is used, non-resistant bacteria are killed but resistant bacteria survive and reproduce, so the population of the resistant strain rises – a change in the inherited characteristics of a population (natural selection) that we can observe happening

Bacteria can reproduce very quickly, so it is possible to observe evolution in bacterial populations

• Evolution in populations that reproduce slowly can take many decades

Darwin’s theory of evolution by natural selection is now widely accepted

Evidence for Darwin’s theory is now available as it has been shown that characteristics are passed on to offspring in genes

• Our understanding of genetics has made clear the mechanism by which natural selection can occur

There is further evidence for evolution in the fossil record and our knowledge of how resistance to antibiotics evolves in bacteria

• Fossils from rocks of different ages show how organisms have changed over time: older fossils, found in older (deeper) rock layers, are generally simpler than more recent ones, and the fossil record shows how organisms from the past are related to species alive today