While much research debates whether properties of ecological networks such as nestedness and connectance stabilize biological communities, few studies mechanistically explain overall network structure and successfully predict novel field observations. For example, only recently have the well-evidenced adaptive foraging of pollinators and the inherent consumer-resource nature of pollination networks been studied in an integrated manner. Additionally, nearly all previous network studies emphasized previously observed empirical patterns without successfully predicting new observations. Many consider such prediction a required indicator of scientific understanding. We address these challenges using Valdovinos’ et al. (2013) consumer-resource approach to pollination networks that mechanistically integrates behaviors and network structures associated with floral rewards and reproductive services in order to model the dynamics of mutualistic systems. We begin by focusing on how adaptive foraging behavior interacts with network architecture to determine the stability, in terms of species persistence, of pollination networks. We then more deeply explored how the modeled mechanisms differentially affected the dynamics, abundance and persistence of more and less generalized plants and animals. Finally, we tested novel predictions emerging from our explorations against intensive field observations of bee foraging.
We found that adaptive foraging stabilized realistically structured (i.e. nested and moderately connected) networks by partitioning the niches between generalist and specialist species. This partitioning increases the persistence of specialist species by increasing the reward consumption by specialist pollinators and the quantity and quality of visits received by specialist plants. In unrealistically over-connected networks, the greater access to more diverse and abundant food sources by more generalized pollinators greatly increases pollinator persistence but also slightly decreases the quality of their pollination services to plants. When adaptive foraging is incorporated in these over-connected networks, pollinators maintain their high persistence but strongly decrease the persistence of generalist plants. This is because all pollinators in over-connected networks with adaptive foraging are generalists that adaptively avoid visiting their most generalized plants. These findings suggest that pollination behaviors and network structures found in nature emerge from balancing generalization, which allows pollinators to benefit from consuming more plant species, and specialization, which allows plants to benefit from deposition of more abundant and less diluted conspecific pollen. Our research shows how networks exhibiting empirically observed structures and behaviors resolve this conflict and successfully predict novel adaptive foraging behaviors corroborated by intensive field observations.