Biological invasions are major drivers of biodiversity loss

Biological invasions have become one of the biggest drivers of biodiversity loss. A new study from CNRS shows that invasive alien species disrupt the behavior, and threaten the survival, of up to 40 percent of birds and 11 percent of mammals. 

According to the researchers, biological invasions threaten the diversity of ecological strategies – the ways in which various species feed, live, function and defend themselves.

The experts report that biological invasions also threaten the global phylogenetic diversity of more than 10 percent of all birds and mammals. Phylogenetic diversity (PD) measures the accumulated evolutionary history of a species, and therefore describes a fundamental aspect of biodiversity.

Ultimately, the results show that the ability of many animals to adapt to environmental changes could be largely lost as a result of biological invasions. The research is providing new insight into the future of ecosystems, including which species could be lost. 

“Our results confirm that invasive alien species (IAS) are likely to cause the selective loss of species with unique evolutionary and ecological profiles,” wrote the study authors.

“Our results also suggest a global shift in species composition away from those with large body mass, which mostly feed in the lower foraging strata and have an herbivorous diet (mammals).”

Globalization has led to an increase in the occurrence of biological invasions. The introduction of so-called invasive species, such as the Asian hornet in France, leads to a decline in certain native species. 

Across island nations, biological invasions are the primary driver of biodiversity loss, with birds being particularly vulnerable. Compared to birds on the mainland, island birds are less able to adapt their strategies to more generalist invasive species.

For example, the kagu is a rare bird that is found in the mountain forests of New Caledonia. It is unique from a phylogenetic standpoint because it is the only remaining member of the Rhynochetidae family.

However, because the kagu does not fly and feeds on the ground, it is in direct competition with new land predators such as invasive rats that have been introduced to the island nation. 

Other bird species that play important roles as pollinators and seed dispersers are also at risk from biological invasions. Their disappearance would have consequences for the functioning of the entire ecosystem.

“Our findings demonstrate the potential impact of biological invasions on phylogenetic and trait dimensions of diversity, especially in the Oceanian realm,” wrote the researchers.

“We therefore call for a more systematic integration of all facets of diversity when investigating the consequences of biological invasions in future studies. This would help to establish spatial prioritizations regarding IAS threats worldwide and anticipate the consequences of losing specific ecological profiles in the invaded community.”

The study is published in the journal Global Change Biology.

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By Chrissy Sexton, Earth.com Staff Writer