Human-mediated transport beyond biogeographic barriers has led to the introduction and 73The transport of species across biogeographic barriers by humans is a key component of 74 global environmental change [1][2][3] . Some of the species introduced to new regions will establish 75 self-sustaining populations and, thus, become a persistent part of the local biota 95We expect regions with higher gross domestic product per capita (GDPpc) or with higher 96 population densities to receive more alien species introductions across taxa (i.e., to experience 97 higher colonisation pressure through trade and transport), resulting in higher EAS richness 7,8,10,21 . 98We also test whether EAS richness patterns follow the latitudinal gradients often observed for 99 native biota, with higher richness in regions with higher mean annual temperature and 100 precipitation 22,23 . We expect island regions to have higher EAS richness than mainland regions, 101as islands are thought to be more prone to the establishment of alien species 12,24,25 . In addition, 102we expect more isolated oceanic islands to have greater EAS richness, as they have been shown 103 to receive more introductions, at least for birds 9 . We also expect coastal regions (as points of human population density, with a weak trend of higher alien richness in wetter regions (Table 1). 125While we only have potential proxy data (GDPpc, population density) for colonisation pressure 126 here (i.e., the total numbers of species introduced) 26 , our results suggest that cumulative numbers 127 7 of EAS are driven to a greater extent by differences in area and the pressure of introductions 128 from human history and activity 1,3,5,12,21 than by climate. 129Island regions have on average higher cross-taxon EAS richness (mean ± 1 S.D. 130proportional cross-taxon richness = 0.17 ± 0.11) than mainland regions (mean ± 1 S.D. = 0.11 ± 131 0.07; Table 1). In addition, models explaining alien richness of island and mainland regions 132 separately reveal that EAS richness is more strongly related to area, GDPpc and population 133 density on islands than in mainland regions (Table 1) (Table 1). Among mainland regions, EAS richness is greater for coastal (mean ± 1 S.D. 139proportional cross-taxon richness = 0.13 ± 0.09) than for landlocked regions (mean ± 1 S.D. = 140 0.10 ± 0.04). Cross-taxon EAS richness on islands tends to be higher for those further from 141 continental landmasses (Table 1). 143 Taxonomic congruence 144The strongest correlations in alien richness between taxonomic groups exist for ants and 145 reptiles (r s = 0.62), followed by birds and mammals, and vascular plants and spiders (both r s = 146 0.55) ( Table 2). For ants and reptiles, EAS richness is high in the Hawaiian Islands, southern 147United States (especially Florida) and Madagascar and the Mascarene Islands (Fig. 1b, 1g). (Fig. 1f, 1h). In Europe, the United Kingdom has the highest established alien 154 plant richness, while Germany has the highest spider richness (Fig. 1h, 1h). Overa...

One of the best-known general patterns in island biogeography is the species-isolation relationship (SIR), a decrease in the number of native species with increasing island isolation that is linked to lower rates of natural dispersal and colonization on remote oceanic islands. However, during recent centuries, the anthropogenic introduction of alien species has increasingly gained importance and altered the composition and richness of island species pools. We analyzed a large dataset for alien and native plants, ants, reptiles, mammals, and birds on 257 (sub) tropical islands, and showed that, except for birds, the number of naturalized alien species increases with isolation for all taxa, a pattern that is opposite to the negative SIR of native species. We argue that the reversal of the SIR for alien species is driven by an increase in island invasibility due to reduced diversity and increased ecological naiveté of native biota on the more remote islands.

Aim:We introduce a high-quality global database of established alien amphibians and reptiles. We use this data set to analyse: (1) the global distribution; (2) the temporal dynamics; (3) the flows between native and alien ranges; and (4) the key drivers of established alien amphibians and reptiles. Location: Worldwide. Methods:We collected geographical records of established amphibians and reptiles from a thorough search across a wide number of sources. We supplemented these data with year of first record, when available. We used descriptive statistics and data visualization techniques to analyse taxonomic, spatial and temporal patterns in establishment records and the global flows of alien species. We used generalized linear mixed models to relate spatial variation in the number of established species richness with variables describing geographical, environmental and human factors. Results: Our database covers 86% of the terrestrial area of the world. We identified 78 alien amphibian and 198 alien reptile species established in at least one of our 359 study regions. These figures represent about 1.0% of the extant global amphibian and 1.9% of the extant global reptile species richness. The flows of amphibians were dominated by exchanges between and within North and South America, and within Europe BIOSKETCHES César Capinha is an ecologist and biogeographer interested in documenting large-scale biogeographical patterns of alien species and in forecasting how these patterns may progress under global change.Hanno Seebens is an invasion ecologist with interests in the global distribution and spread of alien species, using data analysis and modelling.Franz Essl is an ecologist with a focus on invasion ecology, macroecology and conservation biology.