Network of observed invasive alien species costs per country in the Mediterranean. This bipartite network is composed of both species groups and country nodes. Links indicate the cumulative costs of species in countries over 1990–2017. Node size and link thickness corresponds to the cumulative costs. For species nodes, node size represents the total cost they had over all countries. For country nodes, the node size represents the total cost of all species in that country, so large country nodes imply that those countries had large invasion costs.