Biodiversity: (h) in situ and ex situ methods of maintaining biodiversity

The idea

Conservation methods are grouped as in situ (protecting organisms in their natural habitat) or ex situ (protecting them away from their natural habitat). In situ methods include nature reserves, national parks, marine protected areas and habitat restoration; they conserve the species alongside the rest of the community and its ecological interactions, but can be hard to enforce and vulnerable to a single local threat. Ex situ methods include zoos, botanic gardens, seed banks and captive breeding programmes; they protect individuals and genetic material when a habitat is lost or a population is critically small, and can support reintroduction, but are costly, hold limited genetic diversity and do not preserve the original ecosystem. A multiple-choice question will typically give a scenario and ask you to classify the method or to select an advantage or limitation of it.

What earns the marks

• In situ conservation protects species within their natural habitat, for example nature reserves, national parks and marine protected areas.
• In situ methods conserve the whole community and its ecological interactions but may be difficult to enforce or vulnerable to local threats.
• Ex situ conservation protects organisms away from their natural habitat, for example zoos, botanic gardens, seed banks and captive breeding.
• Ex situ methods can protect species when habitat is lost and can support reintroduction, but are costly and hold limited genetic diversity.
• Classify a described method as in situ or ex situ before selecting an advantage or limitation.

Common mistakes and how to put them right

• Reversing the terms, calling a zoo in situ or a reserve ex situ.

  Put it right: In situ means in the natural habitat, ex situ means away from it.

• Assuming ex situ conservation preserves the whole ecosystem.

  Put it right: It protects individuals or genetic material, not the original habitat and community.

• Treating in situ conservation as always successful.

  Put it right: Reserves can be hard to enforce and remain exposed to pollution, climate change or poaching.

Exam tips

• Label each option as in situ or ex situ first, then check whether the stem asks for a method, an advantage or a limitation.
• Match the scenario's location to the habitat to decide the category.
• Reject options that describe a benefit belonging to the other category.