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Global hotspots and correlates of alien species richness across taxonomic groups


Human-mediated transport beyond biogeographic barriers has led to the introduction and establishment of alien species in new regions worldwide. However, we lack a global picture of established alien species richness for multiple taxonomic groups. Here, we assess global patterns and potential drivers of established alien species richness across eight taxonomic groups (amphibians, ants, birds, freshwater fishes, mammals, vascular plants, reptiles and spiders) for 186 islands and 423 mainland regions. Hotspots of established alien species richness are predominantly island and coastal mainland regions. Regions with greater gross domestic product per capita, human population density, and area have higher established alien richness, with strongest effects emerging for islands. Ants and reptiles, birds and mammals, and vascular plants and spiders form pairs of taxonomic groups with the highest spatial congruence in established alien richness, but drivers explaining richness differ between the taxa in each pair. Across all taxonomic groups, our results highlight the need to prioritize prevention of further alien species introductions to island and coastal mainland regions globally.

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Figure 1: Established alien species richness in the 609 TDWG level-4 regions with data available per taxonomic group.
Figure 2: Hotspot and coldspot regions for cross-taxon established alien species richness across eight taxonomic groups, accounting for area and sampling effort.
Figure 3: Effects of area, climate, sampling effort, GDP per capita, human population density and whether a region is coastal on established alien species richness of eight taxonomic groups.

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This research benefited from support from the European Commission (COST Action TD1209). The Deutsche Forschungsgemeinschaft supported H.S. (DFG, grant SE 1891/2-1), M.v.K. (KL 1866/9-1) and M.W. (FZT 118), the Austrian Science Foundation supported F.E., B.L. and D.M. (FWF, grant I2086-B16). P.P. and J.P. were supported by the Academy of Sciences of the Czech Republic (no. RVO 67985939), Praemium Academiae award to P.P. and Czech Science Foundation (project no. 14-36079G). C. Capinha was supported by a postdoctoral grant from the Portuguese Foundation for Science and Technology (FCT/MCTES) and POPH/FSE (EC) grant SFRH/BPD/84422/2012. E.G.-B. was supported by the Spanish Ministry of Economy and Competitiveness (projects CGL2013-43822-R and CGL2015-69311-REDT). C.M. was supported by the Volkswagen Foundation through a Freigeist Fellowship.

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The GloNAF core team (M.v.K., P.P., W.D., F.E., J.P., M.W., H.K. and P.W.), T.M.B., H.S. and B.L. conceived the idea; W.D. coordinated data collation, and designed and led the analyses and writing with major inputs from F.E., D.M. M.v.K., P.P., H.K., M.W., J.P. and P.W., and further inputs from all other authors. Data were contributed by the GloNAF database for vascular plants, E.P.E. and B.G. for ants, C. Capinha, F.E., H.S. and P.G.-D. for amphibians and reptiles, T.M.B. and E.E.D. for birds, C. Casal, E.G.-B., P.F. and N.E.M. for fishes, P.C. and S.L.S for mammals, and W.N. for spiders. D.M. collected and calculated data on region area and sampling effort. C.M. contributed data on completeness of native species richness inventories.

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Correspondence to Wayne Dawson.

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Dawson, W., Moser, D., van Kleunen, M. et al. Global hotspots and correlates of alien species richness across taxonomic groups. Nat Ecol Evol 1, 0186 (2017).

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