Context dependence in community composition of functional traits mediates freshwater fish invasion success in the Laurentian Great Lakes over time

As the number of non-native species introductions continues to increase, the need for tools to predict potential invaders is a central focus in invasion ecology. Trait-based models are a popular method used to predict non-native species success; however, they have many challenges to overcome and often fail to address the role of propagule pressure in failed invasions. Due to a lack of data, many studies cannot incorporate failed invasions into their models examining the success of invaders. Here, we analyzed the relationship between the functional traits of non-native species, both successful and failed, and native species in the Laurentian Great Lakes over three time periods between 1870 and 2010. We only examined failed invasions where there was an environmental match and sufficient propagule pressure for establishment as determined through records of authorized stocking, allowing us to directly test the contribution of traits to invasion success. We evaluated whether nearest neighbor functional distance (NNFD), mean functional distance (MFD), lake, time, and functional traits predicted invasion success and impact using logistic regression models. Our results indicate that species with functional traits associated with r-selected life-history strategies were more likely to establish and predators were more likely to have high impact. While smaller NNFD and MFD values predicted establishment success, higher MFD values predicted high impact. This study examined the role of functional traits in invasion success and demonstrated the importance that a change in community context contributes to regulating invasion success.