# Explain why the genetic diversity of a population is important for its long-term survival when environmental conditions change.

> OCR A-Level Biology A (H420) — 6.6 Populations and sustainability · Explain · 4 marks

> A conservation charity is managing two isolated populations of a rare bird species. Population A consists of 400 individuals with a wide variety of alleles at many gene loci. Population B consists of 40 individuals, all descended from a single breeding pair introduced 20 years ago.

## Mark scheme (4 marks)

1. Greater genetic diversity means more variation in phenotypes within the population
2. Some individuals are more likely to have alleles that are advantageous under the new conditions
3. Natural selection acts on this variation, so better-adapted individuals survive and reproduce
4. A population with low genetic diversity may lack suitable alleles, making extinction more likely

## Key terms

- [genetic diversity](https://www.gradenine.co.uk/glossary/genetic-diversity)

## Related

- [Revision notes for OCR A-Level Biology A (H420)](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-why-the-genetic-diversity-of-5a598d69) · Published by Druglandscape Ltd.