Authors : Joseph A. Tobias1*, James M. Bullock2, Lynn V. Dicks3, Brenna Forester4, Orly Razgour5Affiliations :1 Department of Life Sciences, Imperial College London, Silwood Park, Buckhurst Road, Ascot, SL5 7PY, UK2 UK Centre for Ecology & Hydrology (UKCEH), Maclean Building, Benson Lane, Wallingford, OX10 8BB, UK3 Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK4 U.S. Fish and Wildlife Service, Fort Collins, CO, USA5 Biosciences, University of Exeter, Exeter, EX4 4PS, UK*To whom correspondence should be addressed:

Despite biological invasions are one of the main environmental problems of the twenty-first century, there is still no theoretical or empirical agreement on whether a high phylogenetic relatedness between exotic and native species positively or negatively affect invasion success. To resolve this conundrum, it has been proposed that the effect might be scale-dependent, being negative at smaller spatial scales and positive at larger scales. Here we show that this scale-dependent pattern may be a sampling artefact associated with species-area effects and a non-random pattern of species introductions. We support this conclusion with simulations and empirical data on invaded and non-invaded avian communities in regions from five continents. We further show that at smaller-scales ---where these artifacts are negligible--- invasion success generally increases with the presence of closely-related species, but that predictive accuracy largely depends on considering the influence of human-related disturbances in facilitating invasions.