# Explain why two geographically isolated populations of the same species may, over many generations, develop different adaptations.

> AQA A-Level Biology (7402) — 3.4.4 Genetic Diversity and Adaptation · Explain · 5 marks

> A species of small mammal originally lived across a large continent. A mountain range formed over thousands of years, splitting the population into two groups that could no longer interbreed. Scientists observed that the two groups gradually developed different physical characteristics.

## Mark scheme (5 marks)

1. Each population experiences different environmental conditions / selection pressures
2. Random mutations produce new alleles / genetic variation within each population
3. Individuals with alleles that are advantageous in their local environment are more likely to survive and reproduce
4. Advantageous alleles are passed on to offspring, increasing in frequency in that population
5. Because the two populations are isolated they cannot interbreed, so different alleles / adaptations accumulate separately in each population

## Key terms

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

## Related

- [Revision notes for AQA A-Level Biology (7402)](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-two-geographically-isolated-populations-6eb36e0b) · Published by Druglandscape Ltd.