DISSERTATION RESEARCH: Population genetic structure and the evolution of specialization within a multi-species ant-microbe symbiosis

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Microbial symbionts play key roles in shaping the diversity of life, from disease causing pathogens to beneficial microbes. The evolutionary dynamics of microbial interactions are understood best within single species or between pairs of interacting species; however, further multi-species studies are necessary to understand how these dynamics change within a broader community of symbionts. The fungus-growing ant (Apterostigma dentigerum) is ideal for addressing such questions, as it maintains multiple symbionts, including fungal cultivars, cultivar-attacking pathogens, and mutualistic bacteria whose antibiotic secretions combat infection. Preliminary work has shown that cultivars are not specialized to combat infection by their most common pathogen species; however, the bacteria are likely filling this role. This study will generate population genetic structure data for A. dentigerum and, coupled with bioassay experiments, seeks to understand how host/symbiont transmission and gene flow impact the evolution of specialization within a complex multi-species symbiosis. This study applies long-standing concepts in population genetics and coevolutionary theory within a more complex framework. Because the proposed work speaks directly to the evolutionary dynamics of pathogen resistance and the maintenance of antibiotic potency, the results will have broad health implications. This study will rely on the assistance of undergraduates (including underrepresented minorities), who will become trained in a variety of molecular genetic and microbiological techniques. Finally, the results of this study will be incorporated into the researchers' microbial ecology and evolution course, in addition to annual K-12 public outreach events attended by the researchers.