The great escape: patterns of enemy release are not explained by time, space or climate

When a plant is introduced to a new ecosystem it may escape from some of its coevolved herbivores. Reduced herbivore damage, and the ability of introduced plants to allocate resources from defence to growth and reproduction can increase the success of introduced species. This mechanism is known as enemy release and is known to occur in some species and situations, but not in others. Understanding the conditions under which enemy release is most likely to occur is important, as this will help us to identify which species and habitats may be most at risk of invasion. We compared in situ measurements of herbivory on 16 plant species at 12 locations within their native European and introduced Australian ranges to quantify their level of enemy release and understand the relationship between enemy release and time, space and climate. Overall, plants experienced approximately seven times more herbivore damage in their native range than in their introduced range. We found no evidence that enemy release was related to time since introduction, introduced range size, temperature, precipitation, humidity or elevation. From here, we can explore whether traits, such as leaf defences or phylogenetic relatedness to neighbouring plants, are stronger indicators of enemy release across species.

Automated summary

When a plant is introduced to a new ecosystem, it may escape from its coevolved herbivores, resulting in less damage and increased success for the introduced species. This mechanism, known as enemy release, varies among species and situations. Understanding the conditions for enemy release is crucial for identifying species and habitats that are most vulnerable to invasion. A study comparing herbivory levels on native and introduced plant species found that plants experienced significantly less damage in their introduced range, but no significant relationships were observed with time, space, or climate factors. Further research can explore other indicators of enemy release, such as leaf defenses or evolutionary relationships among species.