Explaining failed invasions using functional traits: An analysis of freshwater fish introductions in the Laurentian Great Lakes

Background/Question/Methods As the number of non-native species introductions continues to increase, the need for tools to predict potential invaders has become a central focus in invasion ecology. More recently, trait-based models have become a popular method used to predict invaders. These models predict the establishment, spread, and/or impact of potential invaders based on ecological and life-history traits. However, trait-based models have many challenges to overcome, and often fail to address the roles of climate match and propagule pressure in failed invasions. Due to a lack of data, many studies cannot incorporate failed invasions into their models when trying to explain the success of some invaders. We analyzed the relationship between the functional diversity of non-native fish species, both successful and failed, and the native fish communities in the Great Lakes in 1920 and 2010. We only examined failed invasions where there was an environmental match and we had a record of deliberate stocking and, thus, sufficient propagule pressure to establish. This allows us to directly test the contribution of biotic interactions and functional traits to the success of an invader.

Results/Conclusions Preliminary results suggest that there is a significant difference in the mean functional diversity of failed non-native, successful non-native, extant native, and extirpated native species. This study is the first to examine the role of functional traits in invasion success by including known failed invaders that had the necessary propagule pressure and environmental conditions required for establishment. Our results suggest that functional diversity can be used to determine the success of a non-native species.