AHL: Biodiversity conservation
IB Biology Higher LevelΒ· Theme A: Unity and Diversity, AHL Topic 10Β· 25 min read
1. In Situ vs Ex Situ Conservationβ β βββHL onlyβ± 7 min
Conservation Approaches
Two broad categories of strategy to preserve threatened biodiversity, grouped by whether species are maintained in their natural habitat.
Example:
National parks are in situ; seed banks are ex situ.
In situ conservation is the preferred long-term strategy, as it preserves entire ecosystems, species interactions, and allows species to continue evolving under natural selection pressures. Ex situ conservation is used as a backup when in situ protection is not feasible, such as when a species is on the brink of extinction in the wild.
An endangered endemic frog species has only 50 individuals left in the wild, in a wetland threatened by urban development. Compare appropriate in situ and ex situ approaches for this species.
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Step 1: Identify in situ strategies: Negotiate to protect the remaining wetland as a fenced reserve, and control invasive predators that are reducing frog populations in their native habitat.
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Step 2: Identify complementary ex situ strategies: Collect a small number of breeding individuals to establish a captive breeding program in a zoo, with the goal of reintroducing offspring back to the protected wetland.
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Step 3: Compare outcomes: In situ preserves the natural wetland ecosystem the frog depends on, but remains at risk from surrounding development. Ex situ guarantees the species does not go extinct, but captive-bred individuals often struggle to survive when reintroduced to the wild.
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Step 4: Conclusion: The most effective conservation program will use a mix of both approaches, not just one.
2. Effectiveness of Protected Areasβ β β ββHL onlyβ± 8 min
Protected areas are the foundation of global in situ conservation. Their long-term effectiveness depends on multiple biological and social factors, not just their legal designation.
Larger protected areas support larger, more genetically viable populations
Connected protected areas (linked by wildlife corridors) allow gene flow and climate adaptation
Indigenous and local community management improves long-term enforcement and success
Strictly protected areas have higher biodiversity retention than multiple-use areas
Explain why a network of small connected protected areas is often more effective than one large isolated protected area of the same total area.
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Step 1: Isolated protected areas are cut off from other habitats, so species cannot shift their ranges if local conditions become uninhabitable due to climate change.
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Step 2: Isolation also prevents gene flow between separate populations, leading to inbreeding depression in small populations, which increases extinction risk.
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Step 3: A connected network linked by wildlife corridors allows species movement for range shifts and maintains gene flow between populations, leading to lower long-term extinction rates for most species.
3. Threats Mitigation and Priority Settingβ β β ββHL onlyβ± 7 min
Conservation resources are limited, so global efforts prioritize regions and species at highest risk of extinction. Biodiversity hotspots are a common framework for setting conservation priorities.
Biodiversity Hotspot
A region that contains at least 1500 endemic vascular plant species and has lost at least 70% of its original native habitat, making it a high priority for conservation investment.
Example:
The California Floristic Province is a recognized biodiversity hotspot.
Outline how invasive alien species threaten native biodiversity and describe one mitigation strategy.
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Step 1: Invasive alien species are non-native species that establish and spread in new ecosystems, outcompeting native species for resources, preying on native species, and altering ecosystem habitats.
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Step 2: The most cost-effective mitigation strategy is prevention: strict border biosecurity checks to stop invasive species from being introduced via trade, travel, or cargo.
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Step 3: For established invasive populations, targeted eradication (e.g. removing invasive rats from seabird islands) can restore native biodiversity if done early before populations become too large.
4. International Conservation Cooperationβ β βββHL onlyβ± 3 min
Biodiversity loss is a transboundary problem, so international agreements are required to coordinate conservation action across national borders. Two major global agreements are commonly tested:
Agreement | Core Goal | Example Activity |
|---|---|---|
CITES | Regulate international trade of endangered species | Ban global ivory trade to reduce elephant poaching |
Convention on Biological Diversity | Set global biodiversity conservation targets | 30x30 goal to protect 30% of land and sea by 2030 |
Explain why international agreements are needed to conserve migratory species like the African elephant.
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Step 1: Migratory species move across multiple national borders, so a single country cannot protect the species across its entire range.
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Step 2: Unregulated poaching in one country can wipe out populations across the entire region, even if other countries have strong protection laws.
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Step 3: International agreements coordinate cross-border anti-poaching action, ban international trade of ivory, and fund habitat protection across all range states, leading to more effective conservation.
5. Common Pitfalls
Wrong move:
Claiming ex situ conservation is a better long-term solution than in situ conservation
Why:
Ex situ cannot preserve entire ecosystems or the natural selection pressures that allow species to continue evolving
Correct move:
Explain that in situ is the preferred long-term strategy, with ex situ used only as a complementary backup
Wrong move:
Assuming all legally designated protected areas are equally effective
Why:
Many 'paper parks' have no on-the-ground enforcement or management, so they offer no real protection for biodiversity
Correct move:
Evaluate effectiveness based on specific factors (size, connectivity, enforcement, community engagement) rather than legal status alone
Wrong move:
Forgetting to mention community engagement in extended response answers
Why:
IB mark schemes consistently allocate marks for social factors of conservation, not just biological factors
Correct move:
Always add a point that involving local and indigenous communities improves long-term conservation success
Wrong move:
Confusing CITES with the Convention on Biological Diversity
Why:
These two agreements have distinct core goals that are commonly tested in multiple choice and short answer questions
Correct move:
Remember: CITES regulates endangered species trade; CBD sets global broad biodiversity conservation targets
6. Quick Reference Cheatsheet
Strategy Type | Example | Key Advantage | Key Disadvantage |
|---|---|---|---|
In situ conservation | National park, wildlife reserve | Preserves ecosystems and natural evolution | Vulnerable to external threats like poaching/climate change |
Ex situ conservation | Seed bank, captive breeding | Guarantees species survival if wild populations are lost | Cannot preserve ecosystems, reintroduction is often difficult |
Connected protected area | Network with wildlife corridors | Supports gene flow and climate adaptation | Requires cross-jurisdictional cooperation |
CITES | International trade regulation | Stops overexploitation of endangered species | Enforcement varies between countries |
7. Frequently Asked
Do I need to memorize specific conservation examples for the exam?
IB Biology extended response questions reward the use of specific named examples, so learning 1-2 named examples for in situ and ex situ conservation will help you earn full marks.
What is the core difference between conservation and preservation?
Conservation allows for sustainable use of natural resources alongside protection of biodiversity, while preservation prioritises protecting habitats from any human use entirely.
When this came up on past exams
AI-estimated based on syllabus patterns β cross-check with official past papers for accuracy. Use only as revision-focus signals.
- 2025 Β· 2
Compare in situ and ex situ conservation
- 2024 Β· 2
Discuss protected area effectiveness
- 2023 Β· 1
Outline CITES role in conservation
Going deeper
What's Next
Biodiversity conservation builds on your knowledge of evolution, classification, and ecosystem ecology, and connects to core themes of sustainability and human impact in IB Biology HL. This sub-topic is frequently assessed in Paper 2 extended response questions, where you will be expected to evaluate competing conservation strategies and support your arguments with specific named examples. Mastering the trade-offs between different approaches will help you answer application-style questions that ask you to recommend strategies for a given threatened species scenario.