The literature on biological invasions is biased in favour of invasive species - those that spread and often reach high abundance following introduction by humans. It is, however, also important to understand the factors that mediate naturalization.
Many studies lump all alien species, and fail to separate introduced, naturalized and invasive populations and species. These biases impede our ability to elucidate the full suite of drivers of invasion and to predict invasion dynamics, because different factors mediate progression along different sections of the continuum.
Processes leading to naturalization act differently in different regions and global biogeographical patterns of plant invasions result from the interaction of population-biological, macroecological and human-induced factors. Research that is explicitly linked to particular stages of the continuum can generate new information that is appropriate for improving the management of biological invasions.