Evolution of cheating in complex underground networks
Mutualistic interactions are ubiquitous in all ecosystems. One of the most prevalent mutualisms is the arbuscular mycorrhizal (AM) mutualism between the majority of land plants and fungi of the Glomeromycota. Plants and their AM fungal symbionts exchange carbon for water and soil nutrients in complex underground networks involving multiple partners. Evolutionary stability is maintained by bidirectional control, such that partners offering the best rate of exchange are rewarded. Nevertheless, the existence of several cheater plant lineages – plants that exploit AM fungi for carbon – demonstrates that the AM ‘fair-trade’ mutualism is vulnerable to subversion. We use phylogenetic frameworks and network analysis to study the evolutionary pathways to the breakdown of the AM mutualism. The results from the proposed research will cumulate in a framework for the evolution and persistence of cheating in the AM mutualism, which contributes to the unraveling of the evolutionary potential of mycorrhizal fungal networks for effective restoration and agriculture.