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

微生物共生体在塑造生命多样性方面发挥着关键作用，从致病的病原体到有益的微生物。微生物相互作用的进化动力学在单个物种内或相互作用的物种对之间理解得最好；然而，有必要进行进一步的多物种研究，以了解这些动态在更广泛的共生体群落中如何变化。种植真菌的蚂蚁(无牙无菌)是解决这些问题的理想之选，因为它保持着多种共生体，包括真菌品种、攻击品种的病原体和互惠共生细菌，它们的抗生素分泌对抗感染。初步工作表明，品种并不专门对抗它们最常见的病原体物种的感染；然而，细菌可能正在扮演这一角色。这项研究将产生牙杆菌的种群遗传结构数据，并结合生物测定实验，试图了解寄主/共生菌的传播和基因流动如何影响复杂的多物种共生中的专门化进化。这项研究在更复杂的框架内应用了种群遗传学和共同进化理论中的长期概念。由于拟议的工作直接涉及病原体耐药性的进化动力学和抗生素效力的维持，因此结果将具有广泛的健康影响。这项研究将依赖于本科生(包括未被充分代表的少数民族)的帮助，他们将接受各种分子遗传和微生物学技术方面的培训。最后，这项研究的结果将被纳入研究人员的微生物生态学和进化过程，以及研究人员参加的一年一度的K-12公众推广活动。

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.