Importing risk: quantifying the propagule pressureestablishment relationship at the pathway level

Methods Our analysis examines the utility and behaviour of pathway-level NIS establishment curves that relate species-level PP to establishment probability. Using theoretical and empirical methods, we examine the behaviour of pathway-level establishment models when species are heterogeneous in their ability to establish. Next, we examine the implications of using PP proxy and historical establishment data to parameterize these models. Finally, we test the model by building an establishment curve for aquarium fish establishments in the United States using import data as a proxy for PP.