The a geographic area of first author affiliation and the study area (where the invasive species were sampled from) (two papers had a global study area and two had a study area of the Northern Hemisphere which are not shown). Multiple geographic areas were recorded for both first author and study locations, but more so for the latter. The number of papers which b used field, lab, review or modelling to collect data or draw conclusions, with the structure of the study shown in stacked bars (Exp. = experimental, Obs. = Observational, N/A = study did not include experiments or observational data) and c the habitat type from where the invasive species were collected.