Integrating intraspecific variation into population dynamics reveals how interacting species persist in mutualistic communities

Abstract

Mutualistic interactions among organisms are fundamental to the origin and maintenance of biodiversity. Yet the study of community dynamics often relies on values averaged at the species level, ignoring how intraspecific variation can affect those dynamics. We propose a theoretical framework for evaluating the extent to which various forms of variation within populations can influence species' persistence in mutualistic systems. Next, drawing from detailed empirical data on plant-pollinator interactions and plant fitness, we quantify intraspecific variation in the mutualistic benefits received by plants and incorporate this variation into estimations of the community's structural stability, a robust theoretical measure of species' likelihood of persistence. Through explicit consideration of intraspecific variation, we are able to demonstrate that having different combinations of specialized and generalized individuals within plant populations promotes the persistence of pollinator communities. Further, we find that these heterogeneous mixtures of plant individuals reduce the probability of exclusion of focal plant species by promoting indirect effects across the broader plant-pollinator community. By providing a framework that explicitly accounts for individual-level variation, we open the door to a better understanding of the mechanisms promoting biodiversity in mutualistic communities and beyond.