In environments where encounters with unfamiliar resources are uncommon and risks associated with native predators are high, invaders should typically lean towards avoidance (Fig. 1, scenario B).
Category I species are high impact invaders that alter native plant communities by displacing native species, change ecological functions or community structures, or hybridize with natives, based on documented ecological damage [10].
Species were selected due to their classification as high impact invaders by the UK Technical Advisory Group for the EU Water Framework Directive.
One particularly stocky invader - high up in the pecking order, judging by the rich array of security passes hanging from his well-cushioned neck - is engaged in a friendly attempt to reassure him.
In the case of cane toad impacts, a capacity for taste aversion learning enables a rapid recovery from initial toad impact; a capacity for adaptive (genetically based) shifts allows recovery over a much longer timescale; and an inability to modify responses by either mechanism results in persistent high vulnerability to the invader (Shine 2010).
For many invaders, this high density appears stable, although the timescale of this stability (years, decades, centuries) is still unclear for many invaders (Simberloff and Gibbons 2004).
This ranking of the species' abilities can explain the current spreading success of the three bromes on the North American continent, and highlight the high potential of prehistoric invaders (European archaeophytes) to become invasive elsewhere.
For example, an invader with higher dominance than all of three resident species will have random Ri stratified in the bottom quartile of set limits Rmin to Rmax.
Invader triggers higher microbial activities through terpene-rich litter inputs to release nitrogen, which facilitates the invasion of A. adenophora.
These could include optimally timing treatments for when only non-native species are active, or using phenological differences to identify species that may have a high potential to be invaders with climate change.
