# Explain how a population of peppered moths could change over time so that dark-coloured moths become more common than pale-coloured moths through natural selection.

> Edexcel GCSE Biology (1BI0) — 4.1 Evolution by natural selection · Explain · 4 marks

> Peppered moths exist in two forms: pale-coloured and dark-coloured. Both forms rest on tree bark. In areas where tree bark becomes darkened by pollution, dark-coloured moths are harder for predators to spot.

## Mark scheme (4 marks)

1. There is variation / a mutation in the population, producing both pale-coloured and dark-coloured moths
2. Dark-coloured moths are better camouflaged on darkened bark and are less likely to be eaten by predators (predation is a selection pressure)
3. Dark-coloured moths are more likely to survive and reproduce, passing on the gene/allele for dark colouration to offspring
4. Over many generations, the frequency of the dark colouration trait increases in the population / dark moths become more common

## Key terms

- [natural selection](https://www.gradenine.co.uk/glossary/natural-selection)

## Related

- [Revision notes for Edexcel GCSE Biology (1BI0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-a-population-of-peppered-20e4fa03) · Published by Druglandscape Ltd.