Abstract
The process of biological invasions is necessary to understand to prevent future invasions and their negative impacts. Ecological theory and empirical work can provide a framework for approaching the process. Extrinsic factors, such as disturbances, can increase the probability of a successful invasion through several mechanisms. Disturbances may decrease native species’ abundances, decrease species diversity, or change community composition. We conducted a microcosm experiment using a container protozoan and rotifer community to examine how disturbances and the timing of the invasion affected the probability of invasion success. Native species richness significantly decreased with disturbance presence, but total native abundance was not affected. Invader abundance and richness significantly increased with increasing disturbance. Invasion timing had no effect on invasion success, implying that changes in native abundance or biomass did not facilitate or prevent invasions. Several native species that dominated post-disturbance communities had lower abundance levels in no-disturbance and invasion treatments, indicating that species in this community may have exhibited trade-offs between competitive ability and disturbance tolerance. These results suggest that changes in species richness and composition are most important in facilitating invasions, and this may be the result of increased vulnerability to invasion in a post-disturbance community dominated by poor competitors. Understanding how species invasions are facilitated by community characteristics can provide further insight to identifying when communities are most vulnerable and how to prevent invasions.