ABSTRACT
Ecosystems are composed of complex networks of many species interacting in different ways. While ecologists have long studied food webs of feeding interactions, recent studies increasingly focus on mutualistic networks including plants that exchange food for reproductive services provided by animals such as pollinators. Here, we synthesize both types of consumer-resource interactions to better understand the controversial effects of mutualism on ecosystems at the species, guild, and whole-community levels. We find that consumer-resource mechanisms underlying plant-pollinator mutualisms can increase the persistence, productivity, abundance, and temporal stability of both mutualists and non-mutualists in food webs. These effects strongly increase with floral reward productivity and are qualitatively robust to variation in the prevalence of mutualism and pollinators feeding upon resources in addition to rewards. This work advances the ability of mechanistic network theory to synthesize different types of interactions and illustrates how mutualism can enhance the diversity, stability, and function of complex ecosystems.
Footnotes
Data Availability: Simulation code will be available upon acceptance at the repository https://github.com/kayla-hale/Multiplex-Dynamics/
Expanded Material: Supplementary Information with 11 supplementary figures and 4 supplementary tables of additional analysis.
We (1) provided more specific definitions of mutualism, stability, and function by addressing these topics in the Introduction and by more clearly defining repeated terms in a new Table 1, (2) increased clarity in the Results section by (a) explicitly presenting our modeling framework in a section entitled ``The multiplex model,'' (b) justifying our parameterization, (c) presenting our pollination mutualism model visually in a new Figure 1, and (d) summarizing quantitative results for each treatment in a new Figure 4, and (3) improved the control treatments by (a) presenting a ``feedback control'' which better addresses the effect of rewards productivity on ecosystem stability and function, (b) clearly describing how the control is derived from the multiplex model in Figure 1, (c) clarifying hypotheses and conclusions, and (d) providing more detailed results and sensitivity analyses in the supplementary information. These revisions improve the readability of the manuscript but do not substantially change the central content of the work or its conclusions.