Sir

Mark Davis suggests in his book Invasion Biology that the discipline should be reabsorbed into general community ecology, as Emma Marris reports in her Review 'The end of the invasion?' (Nature 459, 327–328; 2009). In fact, invasion biology has a much wider remit than the management of a few highly invasive species. The comparison of alien and native species has contributed to a better understanding of population dynamics, ecosystem function and species evolution. The field still has much to teach us about biodiversity and ecological processes in general, and its relevance to conservation policy is growing.

The acceleration of international trade and travel has led to progressive mixing of biota from across the world, introducing increasing numbers of species to new regions. Although our knowledge of the drivers and consequences of these invasions is still poor, the wisdom of distinguishing species in relation to their geographical origin is confirmed by discoveries of the often marked difference between alien and native species in behaviour, traits and impact (see, for example, P. E. Hulme Global Ecol. Biogeogr. 17, 641–647; 2008). However, the position of invasion biology as a separate discipline will continue to be questioned until we have a better framework for understanding the impacts of invasive species, as well as for risk assessment and strategies to deal with them.

Plurality of discourse is, of course, valuable in any science, and Davis's book should help to instil a balanced perspective among scholars in a young field that is still defining its own unique contribution to ecological understanding.