# Explain how adaptive radiation can result in the formation of multiple new species from a single ancestral species.

> IB DP Biology Higher Level (2023 syllabus) — A4.1 Evolution and speciation · Explain · 4 marks

> Adaptive radiation is considered one of the most dramatic examples of evolution, with the diversification of Darwin's finches in the Galápagos Islands often cited as a classic case. A single ancestral finch species colonised the archipelago and gave rise to approximately 15 distinct species, each occupying a different ecological niche.

## Mark scheme (4 marks)

1. A single ancestral species colonises a new environment or enters an environment with available/unoccupied ecological niches.
2. Populations become isolated (geographically or ecologically) and are subject to different selection pressures in different niches.
3. Genetic divergence accumulates between populations over many generations due to different mutations being selected for and/or genetic drift.
4. Reproductive isolation eventually develops between diverged populations, preventing interbreeding and establishing them as separate species.

## Key terms

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

## 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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-adaptive-radiation-can-result-d577c35c) · Published by Druglandscape Ltd.