Symbiosis is an intimate association between two or more different species that is permanent or long lasting. Interactions range from antagonistic (parasitism), where one organism exploits another, to cooperative (mutualism) in which all partners benefit. Throughout the history of life the formation of symbiotic associations has led to increased complexity and diversity in organisms. The fungus-farming ant-microbe symbiosis is, minimally, a quadripartite association. The obligate mutualism between ants and their fungal cultivar is parasitized by a mold called Escovopsis. To defend against infection, the ants cooperate with bacteria that produce antibiotics, which inhibit Escovopsis. This study explores a newly discovered microbe in this symbiosis, a black yeast, that appears to exploit the ant-bacterial mutualism. The research aims to characterize the role of the black yeast within the system, and to determine whether it is a fifth member of the fungus-farming ant-microbe symbiosis. By combining a variety of microbiological, chemical, ecological and phylogenetic techniques, with creative experimental designs such as "fungal choice" and "potential fitness indicator" experiments, this research will shed light on cooperation and conflict among this complex ant-microbe community. Symbiosis and microbial ecology are emerging fields in the biological sciences, and studies exploring novel interactions and processes in natural systems are important to further develop the fields. Research results will be used to educate students at the K-12, undergraduate, and graduate levels, and as a scientific outreach tool through UW-Madison. International collaborations, and deposition of specimens at museums in Latin America, will further increase the dissemination of scientific knowledge.
