Ecological dynamics of multi-mutualist communities

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Mutualisms are interactions between species where both partners benefit from the association. Pollination of plants by insects or birds is a fundamental mutualism interaction of both natural and agricultural communities. Mutualisms produce critical resources required for the persistence of species involved in the mutualistic interactions. For example, pollinators (insects, bird) are essential for reproduction in many crop plants and pollinators are dependent on food obtained from flowers. In natural communities, mutualisms often involve large groups of species that have similar functional roles. For instance, many flowering plant species live together in a community and are pollinated by a number of different insect species. Similar functional roles among species may contribute to the persistence and success of mutualism communities because alternate partners can provide necessary resources. In addition, species with similar functional role could also provide protection from exploiters or parasites of mutualisms that take resources or services without reciprocating. The study will test the effect of numbers of species, degree of role similarity among species on the stability of multi-mutualist communities. The study also will test how the presence of exploiters affects community persistence. The investigators will use a synthetic mutualism in budding yeast. Understanding how mutualisms persist is critical for protection and restoration of natural communities and in creating successful strategies for sustainable farming. The research will create materials for a high school after-school program that will help to bridge science education gaps for underprivileged children. Additionally, the study will provide training for graduate and undergraduate students. The research will examine the properties of multi-species mutualism communities that contribute to their persistence by experimentally manipulating mutualist community structure to assess how changes in species richness and partner redundancy influence persistence. The research will also test how the presence of exploiters influences community persistence and will use the experimental results to develop new theory to identify the key factors in mutualism dynamics. To accomplish this, a newly developed synthetic mutualism in budding yeast will be used to experimentally manipulate mutualist community structure. The study will examine four objectives: 1) How does the structure of multi-mutualist species communities affect community dynamics? Objective 1 experiments will manipulate species richness and symmetry of communities to test how these factors impact persistence. 2) Are multi-mutualist communities buffered from exploitation? Objective 2 experiments will add exploiters to communities to assess how antagonistic interactions impact persistence. 3) How does the presence of redundant mutualist species with similar function influence mutualist investment? Objective 3 will test how increased species richness and functional redundancy influence the resources that mutualists invest. 4) Objective 4 will build a consumer-resource model of multi-species mutualism that captures the dynamics observed in the experiments to identify key parameters that facilitate persistence.