Response of bluebunch wheatgrass to invasion: differences in competitive ability among invader-experienced and naïve populations

1. Invasive species may alter selective pressures on native plant populations, and there is some evidence that competition with invasive plants may lead to differences in competitive ability between populations that have experienced invasion and those that have not. Previous results have varied among species but also among populations of the same species.
2. We conducted a greenhouse experiment to determine whether there was variation in traits, or in ability to tolerate or suppress an invasive species, among populations of a common native grass that had different histories of exposure to competition from an invasive species. Specifically, we grew seeds of a native grass (Pseudoroegneria spicata) collected from 14 wild populations (six from invaded populations and eight from uninvaded populations) and a cultivar (Anatone) alone or in competition with the invasive species (Centaurea stoebe) and measured traits of both species during and at the end of a 100-day growing period.
3. Pseu...