The global threat of invasive alien species

Studies have shown that invasive alien species (IAS) are responsible for a fifth of animal extinctions for which the causes are well-known, but are invasive species a treat to global biodiversity? In this paper, researchers assessed the spatial and taxonomic relationship between IAS and threatened vertebrates worldwide. Using GBIF-mediated occurrences and IUCN Red List data, they determine that IAS play a role in more than a quarter of all threatened vertebrates. Birds and amphibians have the highest share of IAS-threatened species, and the largest IAS-threatened proportion is found among critically endangered species. The study identifies the frog fungus Batrachochytrium dendrobatidis as the IAS that threatens most vertebrate species (amphibians only), whereas rats combined threaten nearly as many species across all vertebrate classes. They finally show how the effects of IAS aren’t equally distributed worldwide, and point to major centres of IAS-threatened species in the Americas, India, Indonesia, Australia and New Zealand.