Trade, transport and trouble: managing invasive species pathways in an era of globalization.
Humans have traded and transported alien species for millennia with two notable step-changes: the end of the Middle Ages and beginning of the Industrial Revolution. However, in recent decades the world has entered a new phase in the magnitude and diversity of biological invasions: the Era of Globalization. This Special Profile reviews the links between the main drivers of globalization and biological invasions and examines state-of-the-art approaches to pathway risk assessment to illustrate new opportunities for managing invasive species. Income growth is a primary driver of globalization and a clear association exists between Gross Domestic Product and the richness of alien floras and faunas for many regions of the world. In many cases, the exposure of these economies to trade is highlighted by the significant role of merchandise imports in biological invasions, especially for island ecosystems. Post-1950, technical and logistic improvements have accelerated the ease with which commodities are transported across the globe and hindered the traceability of goods and the ease of intercepting pests. New sea, land and air links in international trade and human transport have established novel pathways for the spread of alien species. Increasingly, the science advances underpinning invasive species management must move at the speed of commerce. Increasing transport networks and demand for commodities have led to pathway risk assessments becoming the frontline in the prevention of biological invasions. The diverse routes of introduction arising from contaminant, stowaway, corridor and unaided pathways, in both aquatic and terrestrial biomes are complex. Nevertheless, common features enable comparable approaches to risk assessment. By bringing together spatial data on climate suitability, habitat availability and points of entry, as well a demographic models that include species dispersal (both natural and human-mediated) and measures of propagule pressure, it is possible to generate risk maps highlighting potential invasion hotspots that can inform prevention strategies. Synthesis and applications. To date, most attempts to model pathways have focused on describing the likelihood of invader establishment. Few have modelled explicit management strategies such as optimal detection and inspection strategies and assessments of the effectiveness of different management measures. A future focus in these areas will ensure research informs response.