Dissertation Research: Partner Variability and Fitness in a Legume-Rhizobium Mutualism

生物互惠是物种之间的相互作用，在这种相互作用中，两个物种都受益。这些相互作用在自然界中无处不在。在这些互惠关系中，研究得最好的和经济上重要的一种发生在豆科植物和根瘤菌之间，在这种互惠关系中，植物为细菌提供食物和庇护，细菌为植物提供氮。然而，维持这些伙伴之间合作的进化力量却鲜为人知。本项目将研究模式植物紫花苜蓿（Medicago truncatula）与其共生细菌Sinorhizobium meliloti的协同进化。操控温室实验将用于研究共生对双方繁殖成功的影响。这些数据将使我们能够确定互惠关系是否对双方都最有利，还是在有益和寄生之间波动。这项研究将促进我们对自然界中相互作用如何进化的认识，并有助于理解基本的进化过程。这些知识将提高我们管理互惠互动的能力，因为它们通常在作物生产和生态系统恢复中发挥重要作用。此外，深入了解这些关系将提高我们对环境条件的自然和人为变化对共生稳定性的影响的理解。

Biological mutualisms are interactions between species in which both species benefit. These interactions are ubiquitous in nature. One of the best studied and economically important of these mutualisms occurs between legume plants and rhizobial bacteria, a mutualism in which plants provide food and shelter to the bacteria and the bacteria provide nitrogen to the plant. Little is known, however, about the evolutionary forces that maintain cooperation between these partners. This project will investigate coevolution between the model plant Medicago truncatula and its symbiotic bacterium Sinorhizobium meliloti. Manipulative greenhouse experiments will be used to study the effects of symbiosis on the reproductive success of both partners. These data will allow us to determine if mutualisms are optimally beneficial for both parties or fluctuate between being beneficial and parasitic.This research will advance our knowledge of how mutualisms evolve in nature as well as contribute to an understanding of basic evolutionary processes. This knowledge will increase our ability to manage mutualistic interactions, as they often play important roles in both crop production and ecosystem restoration. Moreover, insight into these relationships will improve our understanding of the effects natural and anthropogenic changes in environmental conditions have on mutualism stability.