The global distribution of exotic species is the result of abiotic, biotic and dispersal
filtering processes that shape the movement and success of species outside their native
range. In this study we aim to understand how these filtering processes drive the fluxes
of grass species among regions, the factors that influence which species establish outside
of their native range, and where they do so.

We used national and subnational checklists of native and introduced grass species
to determine the extent to which each region was a source or recipient of exotic grass
species. We asked how species traits may distinguish those grass species that have naturalized
outside their native range from those that have not, and how environmental
conditions are related to the distribution of exotic grass species.

We found that exotic grass establishment is shaped by an array of factors including
characteristics of regions, traits of species and their interactions. Regions with a longer
history of human occupation and larger numbers of native grass species were generally
the most important sources of exotic species. Global flows of species were mostly
driven by a climate match between the native and exotic ranges, but were also highly
asymmetric, with regions with recent human arrival being the major hosts of exotic
grass species. Tall, annual and C4 grass species exhibited particularly high probabilities
of establishment outside their native range.

Despite the idiosyncrasy and stochasticity characteristic of exotic species establishment,
this biogeographical analysis revealed important generalities across this large
plant group. Our results suggest that grass species that have co-occurred with humans
for a longer time may be better adapted to living in anthropogenic landscapes, explaining
the global asymmetry in species introductions.

Environmental predictors, and status (native or introduced) and presence information of 11361 grass species at the national or subnational level (TDWG3 regions, Brummitt 2001)

This dataset contains 3 files:

1) The file "ECOG-04609_Monnet_distribution_data" contains the status - native (N) or introduced (I) - of the grass species (species) in each TDWG3 regions (level3_cod). Source: World Checklist of Selected Plant Families (Royal Botanic Gardens Kew, 2015).

2) The file "ECOG-04609_Monnet_environmental_data" contains the environmental predictors processed for each TDWG3 regions (level3_cod): latitude and longitude; continent; area: surface of the region; temp_mean, temp_min, temp_max: mean, minimum, and maximum annual temperature; pp_mean, pp_min, pp_max: mean, minimum, and maximum annual precipitation; temp_sd: temperature seasonality; pp_cv: precipitation seasonality; hii: Humain Influence Index; gdp: Gross Domestic Product at PPP; fire_frequency: mean fire frequency; velocity: climate change velocity from the Last Glacial Maximum; croplandX, grazingX, pastureX, rangelandX, totalX: mean area covered by cropland / grazing / pasture / rangeland / in total at year X.

3) The file "ECOG-04609_Monnet_introduced_species_list" contains the list of the alien grass species (species) and whether they are considred as cultigens and widely cultivated grass species or not (1/0). Source: World Checklist of Selected Plant Families (Royal Botanic Gardens Kew, 2015).