Ant identity determines the fungi richness and composition of a myrmecochorous seed

Abstract

AbstractMyrmecochory - seed dispersal by ants - is a mutualistic interaction in which ants attracted by seed appendices take them away from the parental plant location, where seeds usually have better development odds. Not all ant species benefit plants, and the mechanisms of those divergent outcomes are still unclear, especially from the perspective of microbial third parties. Here, we explore the effects of seed manipulation on fungi communities promoted by two ant species with contrasting effects on seed germination and antimicrobial cleaning strategies. We hypothesize that: i) fungi richness is higher in seeds manipulated byAcromyrmex subterraneus(species that negatively affect seed germination), followed by unmanipulated seeds and seeds manipulated byAtta sexdens(ant species that increase seed germination) and ii) seeds manipulated byA. sexdens, Ac. subterraneusand unmanipulated seeds present dissimilar fungi compositions. We identified fungal morphotypes in three groups of seeds: i) manipulated byA. sexdens; ii) manipulated byAc. subterraneus; iii) unmanipulated. Seeds manipulated byAc. subterraneusexhibited higher fungal richness than those manipulated byA. sexdensand unmanipulated seeds, indicating that the ant species known to impair germination increases the fungal load on seeds. Additionally, we found thatA. sexdensants were unable to reduce fungal richness compared to unmanipulated seeds. Furthermore, fungal composition differed among all three treatments. Our results underscore the significance of ant species identity in shaping the fungal communities associated with myrmecochorous seeds. Given the potential influence of microbial infection on seed fate, we suggest considering manipulation strategies when evaluating the overall quality of an ant as a seed disperser.