Dark diversity at home describes the success of cross‐continent tree invasions

AbstractAimNon‐native species threaten ecosystems worldwide, but we poorly know why some species invade more. Functional traits, residence time and native range size have been often used as invasion predictors. Here, we advance in the field by linking invasion success to native range parameters derived from dark diversity – a set of species present in the surrounding region that are absent in a study location even if ecological conditions are suitable. We tested whether those parameters improve the description of species success outside their native range.LocationNorth America; Europe and Mediterranean Basin.MethodsFor 170 tree species native in one and non‐native in another region, we defined their invasion success as the number of locations occupied at the non‐native range. The probabilistic dark diversity was estimated based on the species co‐occurrences in their native ranges. It specifies how suitable is a species for a location, even if the species is absent. We calculated two parameters: sum of native location suitabilities (niche breadth proxy) and dark diversity probability (how often a species is absent from suitable locations, indicating niche realization limitations). We explored whether models including the dark diversity parameters performed better than one with a common species range measure, the number of locations occupied. We accomplished our models by adding functional traits, residence time and invasion direction.ResultsInvasion success increased with the sum of native location suitabilities and decreased with dark diversity probability. This model with dark diversity parameters outperformed an alternative using the number of native locations occupied. Our best model included invasion direction, functional traits (including mycorrhizal status) and residence time, but dark diversity parameters remained important predictors.Main conclusionsThe dark diversity parameters can contribute to invasion ecology by linking the species performance in the non‐native range to its niches parameters, derived from the native range.