Why is biodiversity declining, and which conservation methods actually work to protect it?
The reasons biodiversity should be conserved, the causes of biodiversity loss, and the range of in-situ and ex-situ conservation methods used to protect species and habitats.
A focused answer to AQA A-Level Environmental Science 3.1.4, covering reasons to conserve biodiversity, the causes of species loss, and in-situ and ex-situ conservation methods including reserves, captive breeding, seed banks and legislation.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
AQA wants you to explain why biodiversity should be conserved, identify the causes of biodiversity loss, and compare in-situ conservation (protecting species in their habitat) with ex-situ conservation (protecting them outside it), evaluating the methods used. Command words are Explain, Compare and Evaluate, so a balanced judgement is expected on the longer items.
Why conserve biodiversity
- Ecological value. High biodiversity supports stable, resilient ecosystems and the services they provide, such as pollination, nutrient cycling, water purification and climate regulation.
- Economic value. Wild species provide food, timber, medicines and genetic material for breeding new crop varieties; many medicines were first found in wild organisms, and the genetic diversity of crop wild relatives is a reservoir for disease resistance.
- Ethical and aesthetic value. Many argue species have an intrinsic right to exist, and wild places have cultural, recreational and spiritual worth.
Causes of biodiversity loss
In-situ conservation
In-situ methods are usually preferred because they maintain the species within a functioning ecosystem at relatively low cost per species, but they require ongoing protection from poaching, pollution and habitat damage, and they cannot help a species whose habitat has already been lost.
Ex-situ conservation
Ex-situ methods can save a species from immediate extinction and supply individuals for reintroduction, but they are expensive, hold limited genetic diversity (raising the risk of inbreeding, managed using studbooks), and captive-bred animals may struggle to adapt back to the wild.
Legislation and cooperation
International agreements such as CITES (controlling trade in endangered species) and national laws protect species and habitats. Conservation is most effective when in-situ protection, ex-situ backups and legislation work together, with reintroduction projects returning captive-bred individuals to protected habitats once the original threat is reduced.
Exam-style practice questions
Practice questions written in the style of AQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AQA 20196 marksCompare in-situ and ex-situ methods of conserving biodiversity, evaluating the advantages and limitations of each.Show worked answer →
A compare-and-evaluate needs paired points and a judgement. Markers reward strengths and weaknesses of both.
In-situ (nature reserves, national parks, habitat protection): conserves whole functioning ecosystems and lets species continue to evolve and behave naturally, and is usually cheaper per species. Limitations: requires ongoing protection from poaching and habitat damage, and cannot help a species whose habitat is destroyed.
Ex-situ (zoos, captive breeding, botanic gardens, seed banks): can save a species from immediate extinction and supply individuals for reintroduction. Limitations: expensive, holds limited genetic diversity, animals may not adapt back to the wild, and it does not conserve the habitat.
Judgement: in-situ is generally preferred because it conserves the ecosystem, with ex-situ as a vital backup for the most threatened species. Award balanced points and a clear conclusion.
AQA 20224 marksExplain how a captive-breeding programme can reduce the loss of a species, and one reason why captive breeding alone may not be sufficient.Show worked answer →
Markers award marks for the mechanism and for a developed limitation.
Mechanism: captive breeding raises a population in controlled conditions, protecting it from predators, disease and habitat loss, increasing numbers and, with studbooks to avoid inbreeding, maintaining as much genetic diversity as possible, then supplying individuals for reintroduction to the wild.
Limitation: the captive population starts from few founders so genetic diversity is limited and inbreeding is a risk; captive-bred animals may lack survival skills or be unable to adapt back to the wild; and unless the original threat (such as habitat loss) is removed, reintroduced animals will simply die again. Full marks need the genetic or reintroduction limitation, not just expense.
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Sources & how we know this
- AQA A-level Environmental Science (7447) specification — AQA (2017)