Explain how the ecological niche of a specialist species makes it more vulnerable to extinction than a generalist species when environmental conditions change.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
A specialist species has a narrow ecological niche, meaning it relies on a limited range of resources or conditions.
If environmental conditions change, the specialist’s specific required resources or conditions may no longer be available.
A generalist species has a broad ecological niche and can exploit a wide range of resources or tolerate a wide range of conditions, so it is more likely to survive environmental change.
The specialist has limited ability to switch to alternative resources or habitats, so its population size declines and its extinction risk increases.
If environmental conditions change, the specialist’s specific required resources or conditions may no longer be available.
A generalist species has a broad ecological niche and can exploit a wide range of resources or tolerate a wide range of conditions, so it is more likely to survive environmental change.
The specialist has limited ability to switch to alternative resources or habitats, so its population size declines and its extinction risk increases.
Examiner tips
- Use the word ‘narrow’ for specialist and ‘broad’ for generalist. Show the causal link: change → loss of resource → decline. Mention limited flexibility as the key vulnerability.
- Use clear, concise sentences and avoid unnecessary words.
Common mistakes
- Confusing specialist with generalist or vice‑versa. Failing to explain why a narrow niche increases extinction risk.
Mark scheme (4 marks)
- A specialist species has a narrow ecological niche, meaning it relies on a limited range of resources or conditions.
- If environmental conditions change, the specialist's specific required resources or conditions may no longer be available.
- A generalist species has a broad ecological niche and can exploit a wide range of resources or tolerate a wide range of conditions, so is more likely to survive environmental change.
- The specialist has limited ability to switch to alternative resources or habitats, so population size declines and extinction risk increases.
Key terms in this question
ecological niche · specialist species · generalist species · extinction
Related
- All IB DP Biology Standard Level (2023 syllabus) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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