Symbiont Choice in the Attine Ant-Fungus Mutualism

生物学中尚未解决的一个主要问题是如何解释合作和互惠主义的维持。一个尚未研究的稳定物种间互惠关系的机制是伴侣选择，其中一个互惠主义者区分优质和劣质伴侣，并通过优先联系奖励优质伴侣。本文提出了一种以抗真菌共生为研究对象的共生体选择模型。蚂蚁培育真菌克隆的单一培养物作为它们的主要食物来源，而真菌从蚂蚁那里获得营养和病原体的保护。该提案发展了几种抗真菌系统，包括来自美国西南部的切叶蚁，以研究蚂蚁对其真菌施加的共生体选择的遗传后果。从本质上讲，这些实验提出的问题是，蚂蚁花园中通过基因突变产生的品种多样性是否可能在类似于蚂蚁驱动的“人工选择”（共生选择）下进化。因为共生是生命史上一个反复出现的主题，这项研究有望对驱动生物复杂性和多样性的机制产生深入的见解。这些见解可能影响与人类福利直接相关的问题，包括疾病演变和可持续农业的实践。此外，本课程亦会以个案研究的方式，向学生及公众宣传生态、共生及所有生物过程的重要性。

A major unresolved problem in biology is explaining the maintenance of cooperation and mutualism. One unstudied mechanism that stabilizes mutualisms between species is partner choice, where one of the mutualists discriminates between superior versus inferior partners, and rewards the superior types through preferential association. This proposal develops the attine ant-fungus mutualism as a model for the study of symbiont choice. Attine ants cultivate monocultures of fungal clones as their major food source, whereas the fungus receives from the ants both nourishment and protection from pathogens. The proposal develops several ant-fungus systems, including leafcutter ants from the southwestern USA, to study the genetic consequences of symbiont choice exerted by the ants on their fungi. In essence, the proposed experiments ask whether cultivar diversity in ant gardens, arising through genetic mutation, may evolve under an analog of ant-driven "artificial selection" (symbiont choice).Because symbiosis is a major recurring theme in the history of life, this research is expected to generate insights into the mechanisms that drive biological complexity and diversity. Such insights could impact issues directly relevant to human welfare, including disease evolution and the practice of sustainable agriculture. The case study of the attine ant-fungus mutualism will also be used to promote education of students and the public on the importance of ecological, symbiotic, and ultimately all biological processes.