Biology • Year 11 • Module 4 • Lesson 22
Conservation: Strategies, Ethics and Australian Case Studies
Apply in-situ and ex-situ concepts to real data, Australian case studies, and a comparative evaluation across multiple criteria.
1. Interpret data — eastern barred bandicoot captive program
The table below models the eastern barred bandicoot captive breeding program: founder numbers, cumulative captive-bred individuals, and the number reintroduced into predator-proof fenced reserves over four monitoring periods. 7 marks
| Period | Captive founders | Cumulative captive-bred | Released to fenced reserves |
|---|---|---|---|
| 1991–1999 | 40 | 620 | 0 |
| 2000–2009 | 40 | 1,840 | 150 |
| 2010–2019 | 40 | 4,100 | 420 |
| 2020–2021 | 40 | 5,000 | 510 |
Hypothetical data modelled on published Zoos Victoria recovery records.
1.1 Describe the trend in the cumulative number of captive-bred bandicoots across the four periods. 2 marks
1.2 Calculate the percentage of cumulative captive-bred bandicoots that had been released to fenced reserves by 2021. Show your working. 2 marks
1.3 Using lesson content, explain why the program released animals only into predator-proof fenced reserves rather than into open habitat. 3 marks
2. Compare and contrast — in-situ vs ex-situ conservation
Complete the table using information from the lesson. Where a cell is already filled, use it as a clue for the adjacent row. 8 marks
| Criterion | In-situ conservation | Ex-situ conservation |
|---|---|---|
| Definition | Protecting species within their natural habitat | |
| Main tools | Captive breeding, seed banks, zoos, botanic gardens | |
| Cost | ||
| Ecological context | Preserves ecosystem function, predator–prey relationships and evolutionary processes | |
| When used | ||
| Key risk | Threats may still operate inside protected areas (feral predators, weeds) | |
| Australian example | Taronga Zoo captive breeding of the corroboree frog |
3. Case study — the corroboree frog
Read the scenario and answer the questions that follow. 6 marks
Scenario. The southern corroboree frog (Pseudophryne corroboree) lives in the alpine sphagnum bogs of Kosciuszko National Park, NSW. By the early 2000s, chytrid fungus — an introduced aquatic pathogen that attacks frog skin — had reduced the wild population to fewer than 100 individuals. No effective field treatment existed. In response, Taronga Zoo established a captive breeding program that now holds more than 2,000 individuals. Reintroduction into chytrid-treated bog habitats is ongoing, but the wild population remains critically small.
3.1 Identify the specific threat driving the corroboree frog's decline and classify it as biotic or abiotic. 2 marks
3.2 Explain why ex-situ conservation was chosen as the primary response for this species rather than in-situ protection of the national park. 2 marks
3.3 Suggest one reason why the corroboree frog recovery is considered less complete than the eastern barred bandicoot recovery, using lesson content to support your answer. 2 marks
4. Predict and justify — the northern hairy-nosed wombat
The northern hairy-nosed wombat (Lasiorhinus krefftii) exists as a single population of approximately 300 individuals at Epping Forest National Park, Queensland. Conservation managers are debating whether to establish a second population at a separate reserve via translocation. 5 marks
4.1 Predict two conservation benefits of establishing a second wombat population. 2 marks
4.2 Predict one biological risk of translocation and explain how it could threaten the success of the new population. 2 marks
4.3 Based on the risks and benefits you identified, predict whether translocation should proceed. Justify your answer in one sentence. 1 mark
Q1.1 — Trend description (2 marks)
The cumulative number of captive-bred bandicoots rises steadily across all four periods, from 620 to about 5,000 [1]. Growth accelerates in the middle periods (the largest decade-on-decade increases occur between 2000 and 2019) as the breeding program matures [1].
Q1.2 — Percentage released (2 marks)
Working: (510 ÷ 5000) × 100 = 10.2% [1 for correct arithmetic; 1 for expressing the answer as a percentage]. So about one in ten captive-bred animals had been released to fenced reserves by 2021.
Q1.3 — Why fenced reserves only (3 marks)
Foxes were the threat that drove the species to Extinct in the Wild, and they still occupy the open landscape [1]. Releasing animals into open habitat would expose them to the same fox predation, so released individuals would be killed before establishing [1]. Predator-proof fencing is in-situ threat abatement that removes the fox threat at the release site, giving reintroduced animals a safe haven in which to breed [1].
Q2 — Compare-and-contrast table (8 marks — 1 per correct cell)
| Criterion | In-situ | Ex-situ |
|---|---|---|
| Definition | Given (protecting species in natural habitat) | Maintaining populations outside natural habitat as a safety net [1] |
| Main tools | National parks, MPAs, wildlife corridors, threat abatement, restoration [1] | Given (captive breeding, seed banks, etc.) |
| Cost | Lower per species; one area protects many species [1] | High per individual; ongoing facility and staffing costs [1] |
| Ecological context | Given (preserves ecosystem function etc.) | Saves the target species but not its ecological context [1] |
| When used | Preferred wherever viable habitat exists and threats can be managed [1] | Last resort when populations are too small, threats too severe, or habitat gone [1] |
| Key risk | Given (feral predators, weeds) | Adaptation to captivity; genetic drift; loss of wild survival skills [1] |
| Australian example | Gondwana Link corridor; Shark Bay MPA; predator-proof fencing at national parks [1] | Given (Taronga Zoo / corroboree frog) |
Q3.1 — Threat identification (2 marks)
The specific threat is chytrid fungus (Batrachochytrium dendrobatidis), an introduced aquatic pathogen [1]. This is a biotic threat because it is a living organism (a fungus) that directly attacks and kills the frogs [1].
Q3.2 — Why ex-situ was the primary response (2 marks)
Chytrid fungus spread through the water in Kosciuszko National Park, so the wild habitat itself was the source of the threat [1]. Because no effective in-situ treatment for chytrid existed, protecting the national park could not prevent continued deaths — the only way to keep the species alive was to remove individuals and breed them in a disease-free captive facility [1].
Q3.3 — Why corroboree frog recovery is less complete (2 marks)
The eastern barred bandicoot was reclassified from Extinct in the Wild to Endangered in 2021, meaning a self-sustaining managed wild population exists [1]. The corroboree frog remains critically small in the wild and dependent on ongoing captive breeding because chytrid fungus persists in the habitat and cannot yet be eliminated — recovery requires treating or removing the in-situ threat before any lasting wild population can be sustained [1].
Q4.1 — Benefits of a second population (2 marks)
Benefit 1: reduces the risk of catastrophic loss — if disease, fire, or drought wiped out the single Epping Forest population, the species would go extinct; a second site acts as insurance [1]. Benefit 2: increases total genetic diversity by expanding and connecting breeding pools, reducing inbreeding risk in a species with only ~300 individuals [1].
Q4.2 — Risk of translocation (2 marks)
One risk is disease introduction: translocated individuals may carry pathogens or parasites from Epping Forest that could devastate the new population or other wildlife at the destination site [1]. If this occurred it could threaten both the new wombat population and native species in the receiving reserve [1]. (Accept also: stress-related mortality during capture/transport; failure to establish in different habitat conditions.)
Q4.3 — Recommendation (1 mark)
Translocation should proceed because removing the all-eggs-in-one-basket extinction risk outweighs the manageable risks, provided a strict disease-screening protocol is followed before and after movement [1]. (Accept any biologically justified recommendation with reasoning.)