# Explain how natural selection could lead to a population of rock pocket mice living on dark volcanic rock becoming mostly dark-coloured over many generations, starting from a population that is mostly light-coloured.

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

> Rock pocket mice live on rocky ground in North America. They are preyed upon by owls and other birds of prey that hunt by sight. In one region, a volcanic lava flow has created an area of dark rock. A population of mostly light-coloured rock pocket mice has moved into this area.

## Mark scheme (4 marks)

1. There is variation in coat colour within the population / some mice are dark-coloured and some are light-coloured, due to mutation
2. Light-coloured mice are more visible on dark rock and are more likely to be eaten by predators / dark-coloured mice are better camouflaged and less likely to be eaten
3. Dark-coloured mice are more likely to survive, reproduce and pass on the gene/allele for dark colouration to their offspring
4. Over many generations the frequency of the allele for dark colouration increases in the population / the proportion of dark-coloured mice in the population increases

## Key terms

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

## Related

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