There exist few empirical rules for the effects of introduced species, reflecting the context-dependent nature of biological invasions. A promising approach toward developing generalizations is to explore hypotheses that incorporate characteristics of both the invader and the recipient system. We present the first general test of the hypothesis that an invader's impact is determined by the system's evolutionary experience with similar species. Through a meta-analysis, we compared the taxonomic distinctiveness of high- and low-impact invaders in several aquatic systems. We find that high-impact invaders (i.e. those that displace native species) are more likely to belong to genera not already present in the system.