Do alien species always harm ecosystems?

2024-08-04 05:00:00

Alien species refer to plants, animals, fungi and microorganisms that humans carry voluntarily or unintentionally outside their natural distribution areas.

Many of these species have become invasive and pose a threat to the functioning of critical ecosystems.

but An international team of scientists has found that introduced large herbivores have no greater impact on plant communities than native herbivores.

Research results published in journal science Member of the American Association for the Advancement of Science.

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Patricio Pereyra is a researcher at the Admiral Stoney Center for Applied Marine Resources Applied Research and Technology Transfer, who collaborates with a team of scientists based in San Antonio Cistern, Río Negro Province . The institution relies on Conicet and the National University of Comahue.

The work was led by Erick Lundgren of Aarhus University in Denmark. A meta-analysis was conducted on more than 200 studies conducted around the world.

They found that the effects of large herbivores on plant abundance and diversity depended more on their body size and diet than on whether they were native or introduced to their ecosystems.

traces of the past

Large herbivorous mammals play a key role in shaping ecosystems and biodiversity by consuming vegetation, dispersing seeds and nutrients, and causing disturbance.

However, many native giant herbivore species have become extinct or experienced dramatic population declines since the end of the Pleistocene.

Recently, humans have introduced many large herbivores to different corners of the world.

Although these introductions offset to some extent the loss of native megafauna and their functions, introduced megafauna are thought to have a greater negative impact on the ecosystems in which they exist.

As a result, researchers say, in some areas, conservation policies prioritize the eradication or culling of introduced megafauna, even though many of these animals are threatened with extinction in their native ranges.

Pereira, a doctor of natural sciences, said that in the tense relationship between native species and introduced species, many experts prefer native species. “Preferring native species over introduced species is ideological. We have to separate the water. Because it doesn’t make sense to use the birth of species as a conservation variable,” Pereira said.

In the new study, researchers analyzed the impact of megaherbivores (larger animals that eat vegetation) on different plant communities. What is novel is that they found no difference between the impacts of individuals from giant alien fauna and those from native fauna.

Significance of research

“This goes somewhat against the prevailing dogma of invasion science, which says that native species behave one way and non-native species behave another way. In fact, they appear to behave the same way, at least for large That’s true for herbivores,” Pereira said.

Professionals chose large herbivores as subjects of study because they shape ecosystems by consuming vegetation, spreading seeds and creating “disturbances” that can alter the natural environment.

“The impact of herbivores weighing more than 45 kilograms on native and exotic plant diversity and abundance was assessed. The work was conducted globally and examined approximately 4,000 reports on the impact of these mammals on terrestrial plant abundance and diversity. A meta-analysis was conducted of records compiled from 221 publications,” the scientist explained. “We argue that the effects of introduced megafauna should be studied through the lens of functional ecology, just like any other wildlife species,” they said.

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