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

9520728真菌内生菌和草之间的马丁联合从寄生到互惠，是研究相互作用的条件性的理想方法。受感染的植物在种群中的频率可能会随着时间的推移而增加；这经常被引用为与种子携带的内生菌的相互作用是一种互惠互利的证据。假设受感染植物和未受感染植物的相对适合度是恒定的。如果相对适合度不同，草和真菌内生真菌之间的相互作用可能会微妙地平衡，并根据影响成本和收益的环境因素从互惠关系转变为寄生关系。这个项目将测试几个假设影响受感染和未受感染植物的相对适合度的因素。这些因素包括相关的食草动物丰度、植物资源和真菌内生真菌菌株在决定植物的成本和收益的平衡中的作用。目前，人们对互惠中条件结果的程度、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，就很难解决关于互惠共生生态的重要问题。由于许多植物物种，包括重要的农作物，都与真菌内生真菌有关，了解这些互惠互利的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.