How Natural Selection Works
Explain natural selection as the mechanism of evolution: heritable variation + competition for resources + differential survival and reproduction = change in allele frequency over generations
Typical age: 12–14 years
“If your child heard about bacteria becoming resistant to antibiotics, could they explain how that happened using natural selection — without the bacteria ‘choosing’ to change?”
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Needs first
- Classifying Organisms
Natural selection explains the diversity of life that classification systems attempt to organise — KS2 broad classification provides context
- Variation in SpeciesREQUIRED
Natural selection requires heritable variation to act on — understanding the nature of variation is a prerequisite
- The Red Queen Hypothesis
KS3 natural selection provides the mechanism that drives both sides of an evolutionary arms race
- Dinosaur-to-Bird Transition
Advanced biomechanical analysis depends on understanding what fossil evidence can and cannot preserve
- Genetic MutationREQUIRED
Mutation is the ultimate source of heritable variation — understanding this grounds the mechanism of natural selection
- Sexual Selection
KS3 natural selection underpins kin selection, sexual selection, and behavioural game theory as extensions of the same mechanism
Unlocks next
- Evidence for Evolution
Evidence for evolution supports the theory of evolution by natural selection — the mechanism to be evidenced should be understood first
- Extinction & Rapid ChangeREQUIRED
Extinction is what happens when natural selection cannot produce adaptations fast enough — the mechanism must be understood first