# Explain why variation within a population is important for natural selection to occur.

> Cambridge International IGCSE Biology (0610) — 18.3 Selection · Explain · 4 marks

> A population of Arctic foxes living in a snowy environment includes individuals with varying fur thickness. Over many generations, the population comes to consist almost entirely of foxes with very thick fur.

## Mark scheme (4 marks)

1. Variation means individuals within the population have different inherited features / alleles / traits
2. There is competition for resources / mates within the population, so not all individuals survive
3. Individuals with advantageous / favourable features are better suited to survive and reproduce in their environment
4. The favourable alleles are passed on to offspring, so over many generations the frequency of the advantageous feature increases in the population

## Key terms

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

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-variation-within-a-population-369ae26c) · Published by Druglandscape Ltd.