Species charisma, understood as a set of species characteristics and their perception that affect people's attitudes and behaviors, is a highly relevant concept for invasion science, with implications across all stages of the invasion process. However, the concept of invasive alien species (IAS) charisma has not yet been systematically investigated. Here, we discuss this concept, provide a set of recommendations for further research and highlight management implications. We review how charisma affects the processes associated with biological invasions and IAS management, including: effects on species introductions and spread, media portrayals, public perceptions of species management, research attention, and active public involvement in research and management. Explicit consideration of IAS charisma is critical to improve understanding of the drivers of people's attitudes towards particular IAS and planned management measures and strategies, and to implement programs aiming to influence stakeholder perceptions and behavior and to strengthen public engagement. In a nutshell • We discuss the concept of charismatic invasive alien species (IAS), highlight management implications and provide a set of recommendations for further research. • The charisma of IAS might influence all stages of the invasion process, and both charisma and its influence can vary over time and space. • It is a potential hindrance to management actions by affecting public support and contributing to conflicts. • We explore the concept of IAS charisma and its effects on biological invasions and management, including species introductions, media portrayal, public perceptions, opposition to management, research effort and public participation in research and management.

Abstract. The literature suggests that small genomes promote invasion in plants, but little is known about the interaction of genome size with other traits or about the role of genome size during different phases of the invasion process. By intercontinental comparison of native and invasive populations of the common reed Phragmites australis, we revealed a distinct relationship between genome size and invasiveness at the intraspecific level. Monoploid genome size was the only significant variable that clearly separated the North American native plants from those of European origin. The mean Cx value (the amount of DNA in one chromosome set) for source European native populations was 0.490 AE 0.007 (mean AE SD), for North American invasive 0.506 AE 0.020, and for North American native 0.543 AE 0.021. Relative to native populations, the European populations that successfully invaded North America had a smaller genome that was associated with plant traits favoring invasiveness (long rhizomes, early emerging abundant shoots, resistance to aphid attack, and low C:N ratio). The knowledge that invasive populations within species can be identified based on genome size can be applied to screen potentially invasive populations of Phragmites in other parts of the world where they could grow in mixed stands with native plants, as well as to other plant species with intraspecific variation in invasion potential. Moreover, as small genomes are better equipped to respond to extreme environmental conditions such as drought, the mechanism reported here may represent an emerging driver for future invasions and range expansions.