Species in Peril and the Fight Against Extinctions

In the past 500 years, between 150,000 and 260,000 species have gone extinct [1]! People have caused many of these losses. We cut down forests for buildings, change the climate by burning too much fuel, and take too many plants and animals from the wild. Losing just one species might not seem like a big deal. However, when a species disappears, the whole ecosystem is affected. This is because other species that relied on the locally extinct species for food or homes will no longer be able to do so. Healthy ecosystems provide clean air, water, and food, and they even help maintain the climate by capturing greenhouse gases. When we lose species, ecosystems have a harder time recovering from climate shifts and natural disasters.

So, what is being done to help ecosystems? Conservation efforts, done with proper planning, can help to slow or even reverse biodiversity loss. However, this requires teamwork! Community groups, government agencies, scientists, and other organizations may choose to join forces. Some strategies they could use include creating protected areas, restoring habitats, and returning species to places where they have disappeared.

Translocations: a Second Chance for Threatened Species

Globally, scientists use a conservation method called translocations to help protect threatened animals and plants. Translocation means carefully moving species from one area to another, for their preservation. There are different types of translocations, but the one we will focus on in this article is called reintroductions. Reintroductions are a particularly powerful tool to turn back the clock for locally extinct species. Reintroduction means moving plants or animals back into places they once lived in, giving them a second chance to thrive in their natural habitats. This was the premise of Jurassic Park!

On a bigger scale, reintroductions of certain key species could benefit whole ecosystems. A well-known example is the reintroduction of gray wolves to Yellowstone National Park, USA. The return of wolves reduced the large populations of the park’s herbivores, like deer and elk, which the wolves preyed on. In turn, this allowed more plants to grow [2]. Reintroductions and other types of translocations are also useful for plants. Hundreds of plant species have been successfully translocated in Australia alone [3], like the feather-leaved banksia or the crimson spider orchid.

However, reintroductions must be done carefully, as they have previously had low success rates. Common troubles include the lack of information on the species being reintroduced, unsuitable release habitat, and insufficient money for work to be carried out [4]. So, what do successful reintroductions require? This can be different for different groups of plants and animals. For example, the translocation of land animals requires knowledge of habitat and food requirements, genetics, and more (Figure 1).

Enhancing Reintroduction Success Through Genetics

One important but sometimes overlooked consideration when moving animals is their genetics. Differences in the DNA of individual animals in a population create genetic diversity. This is why different traits (like hair or eye color) exist. All populations need genetic diversity to be healthy and adaptable. If populations lose a lot of genetic diversity, they may experience health problems, and they may also lose genes that are important for adapting to environmental changes. For example, if the weather gets warmer, some animals might handle the heat better than others because of their genes. Ensuring that populations maintain enough genetic diversity is important for their long-term survival.

Unfortunately, newly translocated populations are prone to losing genetic diversity. This can happen when too few animals are moved. Also, if animals do not reproduce or survive, their genes will not get passed down to future generations. These challenges can also arise in captive-breeding programs, such as zoos. That means animals translocated from these programs might lose genetic diversity twice—once during captive breeding, and again when released into the wild. Without careful management, translocated populations might not last long.

Boosting Genetic Diversity in Reintroduced Populations

So, how do we make sure that our reintroduced populations have enough genetic diversity? There are three main approaches for keeping genetic diversity during reintroductions (Figure 2). These options include:

• Ensuring enough individuals have been translocated, and that they are not all related to one another (e.g., cousins). This will help the translocated population start with a better amount of genetic diversity.
• Choosing founders from the population with the highest genetic diversity.
• Choosing founders from multiple populations that are genetically different to one another. This allows the translocated population to have more genetic diversity than either of the source populations alone.

This last strategy is called genetic mixing (or genetic rescue) (Figure 3). There are some great examples where genetic mixing has worked really well—like for Florida panthers in the USA, or mountain pygmy possums in Australia. However, many scientists are worried about the potential of outbreeding depression. This happens when different genetics do not work well together, causing individuals to be less healthy. To avoid this, many scientists prefer not to mix populations during translocations. Luckily, new research suggests that outbreeding depression is less common than once believed. For many species, there are more benefits to mixing populations than not mixing them. A recent study even suggested that genetic mixing could be effective for up to two-thirds of threatened species in the USA, but this strategy has only been attempted for a very small percentage of translocations [8].

Bringing Back the Past to Support the Future

To bring species back to where they once lived, scientists need to consider many important things, including the species’ biology, environment, and their genetics. As our ability to collect genetic information improves, translocations have become better informed. This, in turn, has led to higher success rates. Despite being just a tiny molecule, DNA can provide a vast amount of information, including the most effective ways to conserve and bring back populations. By using genetic information combined with other knowledge, scientists can improve the restoration of ecosystems.

Glossary

Biodiversity: ↑ The variety of all living organisms in an ecosystem or on Earth, which includes plants, animals, fungi, and other tiny organisms.

Translocations: ↑ The careful movement of plants or animals from one place to another, by a team of scientists, in order to conserve a species.

Reintroductions: ↑ A type of translocation specifically referring to the act of returning a locally extinct species to its former range.

Genetic Diversity: ↑ The overall diversity in the genes between the individuals of a species.

Captive-Breeding Programs: ↑ Programs that breed endangered or threatened animals in safe, controlled environments to boost their populations and support long-term conservation.

Founders: ↑ The first plants or animals to be moved during a translocation.

Genetic Mixing: ↑ The mixing of animals from different populations to boost genetic diversity.

Outbreeding Depression: ↑ When individuals from two genetically different populations mate, they may produce offspring with reduced fitness and health.

Conflict of Interest

The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

AI Tool Statement

The author(s) declared that generative AI was not used in the creation of this manuscript.

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