# Explain how habitat fragmentation reduces the long-term survival prospects of a population of large mammals occupying a nature reserve that has become isolated from other suitable habitats.

> IB DP Biology Higher Level (2023 syllabus) — A4.2 Conservation of biodiversity · Explain · 4 marks

## Mark scheme (4 marks)

1. Isolation prevents immigration of individuals, reducing gene flow between populations
2. Small, isolated population experiences increased genetic drift, leading to loss of genetic diversity / alleles
3. Increased inbreeding results in expression of harmful recessive alleles / reduced heterozygosity, lowering individual fitness (inbreeding depression)
4. Reduced genetic diversity lowers the population's ability to adapt to environmental change / disease, increasing extinction risk

## Key terms

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

## Related

- [Revision notes for IB DP Biology Higher Level (2023 syllabus)](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-how-habitat-fragmentation-reduces-the-4a15f856) · Published by Druglandscape Ltd.