The equalizing effect of adaptive foraging increases plant coexistence in plant-pollinator networks

Environmental changes have impacted specialist species promoting their replacement by generalists, consequently driving functional homogenization with potential implications for ecosystem function. This problem is particularly relevant for plant-pollinator systems, where numerous rare and specialized species coexist with generalists. Prior research on pollination’s role in plant coexistence shows conflicting results: Lotka-Volterra models suggest pollinators negatively impact coexistence by favoring abundant plants, while empirical studies of modular networks show positive effects through niche partitioning. Using a consumer-resource model and modern coexistence theory, we evaluated how nestedness and adaptive foraging affect plant coexistence in plant-pollinator networks through stabilizing mechanisms (increased intraspecific with respect of interspecific competition) and equalizing mechanisms (reduced fitness differences). Nestedness alone reduces coexistence by increasing fitness differences between generalist and specialist species. However, adaptive foraging promotes coexistence by eliminating these differences through equalizing the total visits generalists and specialists receive per plant. This redistribution of pollinator visits caused by adaptive foraging lowers the threshold of visit quality needed for species to persist, enhancing plant coexistence. Our findings show that when a consumer-resource approach is taken, modern coexistence theory supports a positive effect of animal pollination on plant coexistence via an equalizing effect on visits per plant of pollinators’ adaptive foraging.