Ex-situ Conservation

Ex-situ Conservation: Definition

First things first, what is ex-situ conservation?

Ex-situ vs In-situ

Ex-situ conservation takes place outside natural habitats. In contrast, in-situ conservation takes place within a species' natural habitat. In-situ conservation is often preferred and prioritised. This is because it helps preserve recovering populations in their natural habitat, with minimal disturbance. This strategy helps to create and maintain conditions for species adaptation within their environment. As a result, ex-situ conservation is only used as a last resort or complementary to in-situ strategies.

Uses of Ex-situ Conservation

The uses of ex-situ conservation techniques focus on ensuring the survival of threatened species and maintaining their genetic diversity.

Why Do We Need Ex-situ Conservation?

More than 41,000 species of animal and plant are threatened with extinction around the world.

Threats to biodiversity include:

• Habitat loss and fragmentation

• Overexploitation

• Invasive species

• Pollution

• Disease

• Climate change

With so many species at risk, how do scientists decide which species are most in need of ex-situ conservation?

Criteria for Species Selection

Typically, ex-situ conservation focuses on charismatic, rare, or agricultural species.

To decide if ex-situ conservation is appropriate, ecologists must use a five-step decision-making tool.

1. What is the extinction risk of the species?

2. Can ex-situ management play a positive role?

3. What characteristics and dimensions does the ex-situ population need to meet its conservation goal?

4. What resources and expertise are needed?

5. Is ex-situ conservation suitable for this species?

Extinction Risk

The IUCN Red List determines and classifies species according to their extinction risk. The nine categories are:

• Not Evaluated (NE)
• Data Deficient (DD)
• Least Concern (LC)
• Near Threatened (NT)
• Vulnerable (VU)
• Endangered (EN)
• Critically Endangered (CR)
• Extinct in the Wild (EW)
• Extinct (EX)

Ex-situ Conservation Strategies

Ex-situ conservation strategies vary depending on the target species. They are used for animals and plants – but it's a lot easier to maintain plants than animals!

Animals

Living animals are kept in ex-situ collections such as zoos and aquariums to keep them alive and maintain their genetic diversity. Over 700 million people visit zoos every year.

Fig. 1: Zoos keep many species out of harm's way. Source: Unsplash.

How do zoos help conserve a threatened animal species?

• Research

• Public awareness

• A safe environment free from destruction and predators

• Captive breeding programmes

Captive Breeding Programmes

These programmes aim to increase the number of individuals of a species if the population is very small. Scientists try to maximise genetic diversity within the captive population by using studbooks.

Using studbooks aims to ensure an equal representation of genes. Poor breeders are encouraged to breed, whilst particularly good breeders may be limited. In the future, the captive breeding population may be reintroduced to the wild.

Plants

Ex-situ plant conservation usually takes place in the form of a seed bank. These artificial yet valuable hotspots of biodiversity store millions of seeds as an insurance against extinction, and to maintain genetic diversity.

As well as seed banks, plants can be kept in botanical gardens.

Fig. 2: Greenhouses are often used in botanical gardens to simulate a warmer habitat. Source: Unsplash.

Examples of Ex-situ Conservation

Ex-situ conservation has been successful at keeping species alive.

Back from the Brink

A famous example of captive breeding success is the black-footed ferret, North America's only resident ferret species. They frequently eat rodents, but prairie dogs constitute the majority of their diet.

Unfortunately, many prairie dog populations were eliminated because they caused damage to agricultural fields. As a result, the black-footed ferret experienced a severe decline. In 1987, eighteen ferrets were used to start a captive breeding programme, which has successfully introduced black-footed ferrets back into the wild. However, they remain endangered.

Fig. 3: Since the 1990s, almost 4000 kits have been released back into the wild.

Extinct in the Wild

The Alagoas curassow is a pheasant-like bird found in northeastern Brazil. It is extinct in the wild; all 130 members of the species live in captivity. Little was known about the birds before captivity, as they were seldom seen by scientists. Reintroducing the birds to their natural habitat will be tricky. Most surviving individuals have been hybridised with another curassow species. True Alagoas curassows have limited genetic diversity.

Drawbacks and Benefits of Ex-situ Conservation

The pros and cons of ex-situ conservation depend on the species being conserved.

Animals

Plants

Conserving plants via ex-situ techniques is easier and less disruptive to the species, thus has fewer drawbacks than ex-situ animal conservation.

I hope that this article has clarified ex-situ conservation for you. It's a type of conservation where threatened species are taken out of their natural habitat to be stored or looked after elsewhere. The controlled conditions keep the species safe and provide an invaluable research opportunity, but the artificial environment can affect behaviour and genetic diversity.

^{1. D. Conde, An Emerging Role of Zoos to Conserve Biodiversity, Science, 2011}

^{2. Field Studies Council, Ex-situ conservation management, 2022}

^{3. IUCN, IUCN Red List of Threatened Species, 2022}

^{4. Meryl Westlake, 20 facts to celebrate 20 years of the Millennium Seed Bank, Kew, 2020}

^{5. National Geographic, Black-Footed Ferret, 2022}

^{6. University of Sydney, Captive-bred Tasmanian devils susceptible to car strike, 2017}