Lesson 6 of 8

Natural selection

Goal: Explain how natural selection changes a species over time.

Puzzles for this lesson

In natural selection, the individuals best suited to their surroundings are the most likely to survive and breed.

There is variation. The individuals in a species differ, and some of the differences are inherited. A new difference can start with a mutation: a change in the DNA.
Not all survive. They compete for food and space, and some are eaten or die of disease. Those with features that suit their surroundings are more likely to survive and breed.
The features are passed on. The survivors’ offspring inherit the genes for those features. Over many generations the features become more common, and the species changes. This is evolution.
No moth changes colour. Each moth keeps the colour it inherited. It is the mix of colours in the population that changes.

Your turn

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I can put the steps of natural selection in order.I can apply them to an example.

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Variation The differences between living things

Species A group of living things that can breed together to produce fertile offspring

DNA The chemical that holds genetic information

Gene A section of DNA that controls an inherited feature

Mutation A change in the DNA

Natural selection The best-suited individuals survive, breed and pass on their genes

Evolution The change in a species over many generations

For teachers: AQA 3.10.3 · Cambridge 9Bp.04