Economic drivers of biological invasions: A worldwide, bio-geographical analysis

The introduction of harmful non-indigenous species is generally acknowledged to depend both on the propagule pressure imposed by openness to international trade and on the health of the receiving ecosystem. Bio-geographical factors however play a crucial role in determining the level of risk associated with trade. We develop an analytical treatment of bio-geographical similarity between trade partners, within a model that links the incidence of invasive species to resource extraction, pollution and to import volumes disaggregated by country and region of origin. The model, estimated with data on invasive species of all taxa in 123 countries, shows that considering the geographical structure of trade flows and the bio-geographical similarity between sources and destinations substantially improves our understanding of the drivers of biological invasions. The results allow us to identify, in a worldwide perspective, the relative risk of biological invasions (by habitat and organism type) entailed by different commercial partners.