# Explain how the introduction of an invasive species can lead to a reduction in the biodiversity of a native ecosystem.

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

## Mark scheme (4 marks)

1. Invasive species often lack natural predators, parasites, or diseases in the new environment, allowing their populations to grow unchecked.
2. The invasive species competes with native species for resources such as food, space, or light, reducing the fitness and population size of native species.
3. Invasive species may prey directly on native species that have not evolved anti-predator defences against them, causing local extinctions.
4. Loss of native species reduces species richness/diversity, which can destabilise ecosystem functioning and trigger further losses through disrupted food webs or trophic cascades.

## Key terms

- [invasive species](https://www.gradenine.co.uk/glossary/invasive-species)
- [biodiversity](https://www.gradenine.co.uk/glossary/biodiversity)

## Related

- [Revision notes for IB DP Biology Standard 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-the-introduction-of-an-1e67609c) · Published by Druglandscape Ltd.