GCSE Biology · Edexcel 1BI0 · Topic 4A
Evolution and natural selection
Key points
- Evolution is the change in the inherited characteristics of a population over time.
- Natural selection: there is variation in a population, usually from mutation; individuals compete for resources; those with better-adapted characteristics survive and reproduce; they pass on their alleles, so these become more common.
- Darwin developed the theory; Wallace independently came to similar ideas. Evidence from fossils and genetics has since supported it.
- Antibiotic resistance: a mutation lets a bacterium survive an antibiotic; it reproduces quickly, so the resistant strain spreads. This is evidence of evolution happening today.
- Bacteria are useful for studying evolution because they reproduce so quickly that changes can be seen in a short time.
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Evolution is the gradual change in the inherited characteristics of a population over time. This sub-topic sets out Darwin's theory of natural selection, the evidence for it and why antibiotic-resistant bacteria are evolution you can watch.
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