Dissertation Research: Balancing Costs and Benefits in a Mutualism: Conditionality in the Interaction Between the Grass, Hystris patula and its Fungal Endophyte

小行星9520728 真菌内生菌和草之间的关联范围从寄生到互惠，是研究相互作用的条件性的理想选择。 种群中受感染植物的频率可以随着时间的推移而增加;这经常被引用为与种子传播的内生菌相互作用是互利共生的证据。 假设感染和未感染植物的相对适合度是恒定的。 如果相对适合度不同，草和真菌内生菌之间的相互作用可能会微妙地平衡，并根据影响成本和效益的环境因素从互利共生转变为寄生。 这个项目将测试几个因素，假设影响相对健康的感染和未感染的植物。 这些包括相关的食草动物丰度，植物资源和真菌内生菌菌株在确定植物的成本和效益平衡中的作用。 目前对互惠关系中条件结果的程度、决定结果的机制或结果变化的后果知之甚少。 如果没有这些信息，就很难解决关于互利共生生态学的重要问题。 由于许多植物物种，包括重要的农作物，都有相关的真菌内生菌，了解这些互利相互作用背后的机制也具有相当大的应用价值。

9520728 Martin Associations between fungal endophytes and grasses range from parasitic to mutualistic, and are ideal for studying the conditionality of interactions. Frequencies of infected plants in populations can increase over time; this is often cited as evidence that the interaction with seed-borne endophytes is a mutualism. The assumption is that relative fitnesses of infected and non-infected plants are constant. If relative fitnesses vary, the interaction between grasses and fungal endophytes may be delicately balanced, and shift from mutualism to parasitism depending upon environmental factors affecting costs and benefits. This project will test several factors that are hypothesized to affect the relative fitness of infected and non-infected plants. These include the roles of associated herbivore abundance, plant resources, and fungal endophyte strain in determining the balance of costs and benefits to the plant. Little is currently known about the extent of conditional outcomes in mutualisms, the mechanisms that determine outcomes, or the consequences of variation in outcome. Without this information it will be difficult to address important questions about the ecology of mutualisms. Since many plant species, including important agricultural crops, have associated fungal endophytes, understanding the mechanisms behind these mutualistic interactions also has considerable applied value.