Explain why the in situ conservation of an endangered plant species in its native habitat is generally considered more effective than ex situ conservation in a botanical garden.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
1. In situ conservation keeps the plant in its natural habitat, preserving the ecological interactions it relies on, such as pollinators, seed dispersers and mycorrhizal fungi.
2. It allows natural selection to act on the population, maintaining genetic diversity and adaptive potential.
3. Ex situ collections in botanical gardens usually contain only a few individuals, increasing the risk of inbreeding and genetic drift.
4. Protecting the habitat in situ also benefits many other species, whereas ex situ preserves only the single species in isolation.
2. It allows natural selection to act on the population, maintaining genetic diversity and adaptive potential.
3. Ex situ collections in botanical gardens usually contain only a few individuals, increasing the risk of inbreeding and genetic drift.
4. Protecting the habitat in situ also benefits many other species, whereas ex situ preserves only the single species in isolation.
Examiner tips
- Use the word ‘maintains’ and ‘preserves’ to link to the mark scheme points.
- Show the contrast between natural selection in situ and limited genetic sample ex situ.
- Mention the ecosystem benefit as a separate point to hit the full 4 marks.
Common mistakes
- Confusing ex situ with in situ, or vice versa.
- Failing to mention genetic diversity or ecosystem benefits.
- Using vague terms like ‘good’ instead of specific interactions such as pollination.
Mark scheme (4 marks)
- In situ conservation maintains the natural ecological interactions (e.g. pollination, seed dispersal, mycorrhizal associations) that the species depends on for survival and reproduction.
- In situ conservation allows natural selection to continue, maintaining the genetic diversity and adaptive potential of the population.
- Ex situ conservation in a botanical garden typically holds only a small sample of individuals, increasing the risk of inbreeding and loss of genetic diversity through genetic drift.
- In situ conservation protects the entire ecosystem / habitat, benefiting many other species simultaneously, whereas ex situ only preserves individual species in isolation.
Key terms in this question
in situ conservation · ex situ conservation
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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