Third-party mutualists have contrasting effects on host invasion under the enemy-release and biotic-resistance hypotheses

Abstract

Plants engage in complex multipartite interactions with mutualists and antagonists, but these interactions are rarely included in studies that explore plant invasiveness. When considered in isolation, we know that beneficial microbes can enhance an exotic plant's invasive ability and that herbivorous insects often decrease an exotic plant's likeliness of success. However, the effect of these partners on plant fitness has not been well characterized when all three species coevolve. We use computational evolutionary modeling of a trait-based system to test how microbes and herbivores simultaneously coevolving with an invading plant affect the invaders' probability of becoming established. Specifically, we designed a model that explores how a beneficial microbe would influence the outcome of an interaction between a plant and herbivore. To model novel interactions, we included a phenotypic trait shared by each species. Making this trait continuous and selectable allows us to explore how trait similarities between coevolving plants, herbivores and microbes affect fitness. Using this model, we answer the following questions: (1) Can a beneficial plant-microbe interaction influence the evolutionary outcome of antagonistic interactions between plants and herbivores? (2) How does the initial trait similarity between interacting organisms affect the likelihood of plant survival in novel locations? (3) Does the effect of tripartite interactions on the invasion success of a plant depend on whether organisms interact through trait similarity [ -017-9912-5 plants to invade under the ERH but that beneficial microbes increase the probability of plant survival in a novel range under both hypotheses. To our knowledge, this model is the first to use tripartite interactions to explore novel species introductions. It represents a step towards gaining a better understanding of the factors influencing establishment of exotic species to prevent future invasions.

Invasive alien plant species: Their impact on environment, ecosystem services and human health

“…Also, studies on the role of plant-microbe/insect interactions (both mutualist and antagonist) are necessary for elucidating the mechanisms of IAPS spread (Jack et al, 2017). Nutrient enrichment in both the terrestrial and aquatic ecosystems plays a vital role in the success of IAPS in new habitats (Aragón et al, 2014;Uddin and Robinson, 2018); for example, an increased level of nitrogen in soils is found to help Bromus tectorum, (annual cheat grass), to outcompete the native flora (Morris et al, 2016).…”

Plant invasion in protected areas, the Indian Himalayan region, and the North East India: progress and prospects

“…The interaction of IAP with belowground microbial consortium in invaded regions can also be inextricably linked with their successful spread (Jack et al 2017). The role of microbial diversity in accelerating the invasive spread can be explored with advancement in molecular oromic tools, as demonstrated in the cases of Eupatorium adenophorum and Ageratina adenophora (Kong et al 2017) and Impatiens glandulifera (Gaggini et al 2018).…”

Trait-based modelling in ecology: lessons from two decades of research

“…There were also four equation-based models in this section addressing nutrient competition in an earth system model (Zhu et al, 2016), trade-offs of defensive plant traits in plant-herbivore interactions (Mortensen et al, 2018), plant-soil feedback mediated by litter and microorganisms (Ke et al, 2015), and three-way interactions between a plant, a herbivore and a beneficial microbe in the context of biological invasions (Jack et al, 2017).…”