The Establishment of Invasive Species

In the continuum of invasion phases, establishment stands at the interface between the initial introduction of propagules and the integration of the invader into the ecological community. Although the edges of this transitional phase tend to blur, invader establishment is generally related to the survival of initially-transported individuals to form reproducing and expanding populations, influenced both by the characteristics of the invader and the receiving ecosystem. In practice, however, it is often difficult to distinguish between the factors operating in the arrival and establishment phases, because most of the information available is for invaders that have successfully negotiated both and have survived to form conspicuous incursions (Chap. 7, Johnston et al.; Chap. 8, Miller and Ruiz). We often know relatively little about how many invasions fail, when they fail, and why.