title: The intermediate distance hypothesis of biological invasions.
abstract: Biological invasions are a worldwide phenomenon, but the global flows between native and alien regions have rarely been investigated in a cross-taxonomic study. We therefore lack a thorough understanding of the global patterns of alien species spread. Using native and alien ranges of 1380 alien species, we show that the number of alien species follows a hump-shaped function of geographic distance. We observe distinct variations in the relationship between alien species exchanges and distance among taxonomic groups, which relate to the taxa-specific dispersal modes and their pathways of introduction. We formulate a simple statistical model, combining trade volume and biogeographic dissimilarity, which reproduces the observed pattern in good agreement with reported data and even captures variations among taxonomic groups. This study demonstrates the universality of the intermediate distance hypothesis of alien species spread across taxonomic groups, which will help to improve the predictability of new alien species arrivals.
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Carl-von-Ossietzky Straße 9-11, 26111, Oldenburg, Germany.|Division of Conservation, Landscape and Vegetation Ecology, University of Vienna, Rennweg 14, 1030, Vienna, Austria.|Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, 60325, Frankfurt am Main, Germany.
authors.forename: Hanno
authors.initials: H
authors.lastname: Seebens
authors.affiliation: Division of Conservation, Landscape and Vegetation Ecology, University of Vienna, Rennweg 14, 1030, Vienna, Austria.
authors.forename: Franz
authors.initials: F
authors.lastname: Essl
authors.affiliation: Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Carl-von-Ossietzky Straße 9-11, 26111, Oldenburg, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Blasius
mesh_terms: D063147:Animal Distribution; D000818:Animals; D005843:Geography; D058865:Introduced Species; D007448:Invertebrates / Q000502:physiology*; D008954:Models, Biological; D015233:Models, Statistical; D063148:Plant Dispersal; D011157:Population Dynamics; D014714:Vertebrates / Q000502:physiology*
keywords: Biogeography; exchange; flows; macroecology; non-native species; origin; patterns of global spread; trade