The effects of the exploiters (non-pollinating insects) on mutualistic interactions between the plant and its pollinator

Abstract: Mutualistic interactions between, for example, plants and pollinators play a crucial role in maintaining the biodiversity of ecosystems, while non-pollinating insects (exploiters) that exploit plants are commonly thought to have destabilizing effects. The long-term, i.e., evolutionary time scale, effects of such potential destabilization is however largely unknown. The eco-evolutionary implications of exploiters on plants and their pollinator community thus need to be studied in more detail. In this project, I formulate a functional trait-based model of interacting species to explore the effects of exploiters on the trait evolution of plants and pollinators. I use an abstract model that allows for the generalization of important functional traits such as the proboscis length of the pollinator and the exploiter, and corolla tube depth of plant flowers. I simulate a system of plants and pollinators that interact mutually and I use it as a reference point to analyze the effect of an introduction of exploiters in the system. More specifically, I simulate the introduction of different types of exploiters, i.e., different proboscis’s lengths and their effect on the reference plant-pollinator system. My results suggest that exploiters will reduce both plant and pollinator population abundance in an ecosystem but they do not necessarily destabilize the mutualistic interactions. Instead, exploiters induce selective pressure on both plant and pollinator trait co-evolution. The exploiters, for example, reduce the fitness of plants, leading to the selection of the functional traits of the plants to evolve avoidance of the exploitation. Furthermore, the pollinator will co-evolve with the plants to improve their fitness because of the mutualistic relationship between them. These results improve our understanding of the mechanism of the exploiters' stressor driving the co-evolution of plants and pollinators. Understanding that may inform human interventions for biodiversity protection and ecosystem stability in the natural plant-pollinator-exploiter network.