Invasion syndromes: a systematic approach for predicting biological invasions and facilitating effective management

Abstract

Our ability to predict invasions has been hindered by the seemingly idiosyncratic contextdependency of individual invasions. However, we argue that robust and useful generalisations in invasion science can be made by considering ''invasion syndromes'' which we define as ''a combination of pathways, alien species traits, and characteristics of the recipient ecosystem which collectively result in predictable dynamics and impacts, and that can be managed effectively using specific policy and management actions''. We describe this approach and outline examples that highlight its utility, including: cacti with clonal fragmentation in arid ecosystems; small aquatic organisms introduced through ballast water in harbours; large ranid frogs with frequent secondary transfers; piscivorous freshwater fishes in connected aquatic ecosystems; plant invasions in high-elevation areas; tall-statured grasses; and tree-Electronic supplementary material The online version of this article (

Effects of species traits and abiotic factors during the stages of plant invasions

“…Although sometimes questioned in studies on species invasions (cf. Catford et al, 2009, but see Thuiller et al, 2006), our results provide some insights into an “invasion syndrome” relative to the native community and the stages of invasion (question 2, table 1; Novoa et al, 2020). In fact, invasive species are more similar to native species than alien species in terms of their trait characteristics (cf.…”

Double trouble: the implications of climate change for biological invasions

“…Long-term monitoring of alien and native taxa offers an important tool for tracking invasions and gaining first insights into impacts. While context dependency in invasions already poses a notable challenge to their effective and efficient management (Novoa et al in 2020), this is likely to be exacerbated by a changing climate. However, through proactive and adaptive management our ability to prevent and manage invasions under these challenging circumstances will be enhanced.…”

“…This has led to attempts to use generalisations at a broad-scale to enhance understanding (e.g. Hui et al 2013), but this can oversimplify patterns and have many exceptions (Novoa et al 2020). A contrasting approach has been to focus on detailed case studies that comprehensively document individual invasions, but such results can lack generality (Robinson et al 2017).…”

“…A contrasting approach has been to focus on detailed case studies that comprehensively document individual invasions, but such results can lack generality (Robinson et al 2017). Invasion syndromes (sensu Novoa et al 2020) offer an approach for identifying generalities in invasions that are evident when grouping pathways, alien species traits and ecosystem characteristics that display predictable dynamics and impacts. The implication is that specific management approaches are thus identifiable per syndrome.…”

“…This conceptual leap is an important step towards accounting for context dependency of invasions in light of climate change, as pathways, species traits and recipient environments could all be affected into the future. While some invasion syndromes have been identified (Novoa et al 2020), for this approach to be fully tested, it needs to be applied to more systems. In the context of future climate change, invasion syndromes provide a theoretical foundation for hypothesis testing research.…”