Abstract
Invasive plants often use mutualisms to establish in their new habitats and tend to be visited by resident pollinators similarly or more frequently than native plants. The quality and resulting reproductive success of those visits, however, have rarely been studied in a network context. Here, we use a dynamic model to evaluate the invasion success and impacts on natives of various types of non-native plant species into thousands of plant-pollinator networks of varying structure. We found that non-native plants producing high amounts of floral rewards but visited by few pollinators at the moment of their introduction were the only plant species able to invade the networks. This result is determined by the transient dynamics occurring right after the plant introduction, when the pollinator species visiting the introduced plant are low in abundance so it takes them a large amount of foraging effort to deplete the non-native rewards to the reward threshold that determines the equilibrium of the system. This large increase in foraging effort strongly increases the quality of their visits to the introduced plant which allows the plant to invade. Native pollinators visiting the successful invader increased their abundance but the reallocation of their foraging effort from the native plants to the invader reduced the quantity and quality of visits to native plants and made the networks more modular and nested. These effects were buffered by plant richness. Interestingly, changes in visitation structure only caused a minimal decline in native plant abundance and no extinctions. Our results call for evaluating the impact of invasive plants not only on visitation rates and network structure, but also on processes beyond pollination including seed production and recruitment.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
This version of the manuscript has been revised to improve clarity of the main novelties of the work
