Temporal shifts in trait profiles of non-native vertebrate introductions worldwide

Résumé fourni par la source

Biological invasions drive global biodiversity change, altering ecosystem functioning, restructuring communities, and affecting human well-being. While extensive research has aimed at identifying traits associated with invasion success, far less attention has been given to whether the traits of non-native species have changed over time. Here, we provide the first global assessment of temporal changes in trait profiles of non-native terrestrial and freshwater vertebrates. Using the Alien Species First Records Database, we compiled first-record data for 1,931 species of five taxonomic groups (amphibians, birds, mammals, reptiles, and freshwater fishes) introduced between 1800 and 2019. For each species, we assembled key functional and ecological traits, including body size, habitat use, diet, native range characteristics, and climatic niche properties. Using these data, we assessed monotonic relationships between year of first introduction and each trait using Kendall’s rank correlations within each taxonomic group. We also evaluated multivariate relationships, accounting for trait redundancy, using generalised linear mixed models and boosted regression trees. Across taxa, we detected clear temporal shifts in trait composition. Introductions increasingly involve species native to lower latitudes, indicating a growing contribution of tropical-origin species. Native range size declined over time in mammals, birds, and fishes, and body size decreased in mammals and fishes. Dietary trends were taxon-specific: carnivores increased in mammals and birds but declined in fishes, while herbivores decreased in birds and reptiles but increased in fishes. Multivariate analyses revealed consistent cross-taxon patterns: earlier introductions involved larger-bodied, widespread species from multiple continents with broader thermal niches and temperate origins, whereas recent introductions involve species from warmer climates with narrower niches and more restricted distributions. Introduction timing was also structured by continent. Together, our findings show that vertebrate invasions are undergoing systematic shifts in functional and biogeographic composition. Introductions are increasingly dominated by tropical, smaller-bodied, and range-restricted species, consistent with globalisation expanding the pool of introduced taxa. These changes indicate ongoing functional reassembly of recipient communities, with substantial implications for ecosystem processes, trophic dynamics, and future invasion risks.

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