Searching for non-indigenous species: rapidly delimiting the invasion boundary

Invasive species are increasingly being recognized as a driver of global environmental change, causing both economic and environmental damages (Mack et al., 2000). These effects will likely be exacerbated as the rate of introduction of exotic species worldwide accelerates in conjunction with global trade (Hulme, 2009). Not surprisingly, there is consensus in the scientific community that society should invest in improved methods to deal with invaders, as these may pay dividends in terms of reduced impacts caused by the invader (Lodge et al., 2006). In an ideal world, we would identify and prevent the introduction of harmful exotic species. Failing that, we would be able to react quickly and eradicate an invader, or at least control its spread, and therefore the potential damages that it might cause (Veitch & Clout, 2002). For many management options, the first step is to determine the extent of spread – to Department of Biology, McGill University, Montreal, Quebec H3A 1B1, Canada, School of Environment, McGill University, Montreal, Quebec H3A 2A7, Canada, School of Business, Economics, and Public Policy, University of New England, Armidale, 2350, NSW, Australia, School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia