Biology Module 2 - 5.variation and natural selection 5.7 explain how natural selection may be an agent of consistency or an agaent of change

5.7 explain how natural selection may be an agent of consistency or an agent of change


Stabilising selection - environment stable as same alleles selected for every successive generation


Diagram showing stabilising selection

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Directional selection - this is a change in environment or appearance of a new allele. So there is a change in characteristic for successive generation (evolution)

Diagram showing directional selection

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Disruptive selection - selection which favours the extremes of a range in the population which leads to the formation of two new species.


Diagram showing disruptive selection

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