DISSERTATION RESEARCH: Flowers as hubs of nectar-microbe diversity and dispersal in flower visitor networks

许多植物只有在蜜蜂、黄蜂、甲虫、苍蝇和蝴蝶等飞虫将花粉沉积在花上时才能受精。当这些昆虫四处走动收集花蜜和花粉时，它们也倾向于四处传播微生物，如酵母、细菌和病毒，这些微生物会影响植物或其他花的来访者。例如，这些微生物中的一些通过花朵感染作物，一些感染蜜蜂和大黄蜂群体，还有一些影响昆虫是否被花朵吸引。虽然我们知道这些花微生物是由昆虫移动的，并影响它们所附着的植物，但我们对开花植物群落中花微生物的分布有多可预测知之甚少。本研究旨在了解昆虫访问花的模式如何影响花上微生物的分布。了解这一点很重要，因为它可以帮助解决对我们的食物和纤维生产以及本地生态系统至关重要的植物和昆虫的管理问题。寄生在花蜜中的微生物可以改变花对传粉者的吸引力，从而影响传粉服务的成功。由于花蜜微生物主要以访花者为主，因此它们对访花者网络结构具有很大的影响和被影响的潜力。然而，植物与其访花者和花蜜微生物的相互作用尚未在网络框架中考虑。该项目的目的是验证中心植物物种（具有高度多样性的访花植物物种）在本地植物群落中也是花微生物多样性和传播的中心的假设。众所周知，网络枢纽是造成动物物种内不成比例的病原体传播（“超级传播者”）的原因。在访花网络中，中心植物可能是植物间花微生物的超级传播者。本计划的目标是建立植物、访花者及花蜜微生物组成的资料集，并以高海拔湿草甸植物群落中访花者变异较大的物种——台湾水仙进行操控实验。在植物水平上，利用模拟模型来评价访客多样性和访客频率对花蜜微生物多样性的影响。研究人员将对某些花是花蜜微生物多样性中心的假设进行实证检验。

Many plants can only be fertilized when pollen is deposited on flowers by flying insects such as bees, wasps, beetles, flies, and butterflies. While these insects move around gathering nectar and pollen from flowers, they also tend to move around microbes such as yeast, bacteria, and viruses that can impact the plant or other flower visitors. For example, some of these microbes infect crops through the flowers, some infect honeybee and bumblebee colonies, and others affect whether or not an insect is attracted to the flower. While it is known that these floral microbes are moved around by insects, and affect the plant they land on, little is known about how predictable the distribution of floral microbes are in flowering plant communities. This research seeks to understand how the pattern of insect visitation to flowers affects the distribution of microbes on flowers. It is important to learn this because it could help address management of plants and insects that are critical to our food and fiber production as well as native ecosystems. Nectar-inhabiting microbes can alter floral attractiveness to pollinators and thus shape the success of pollination services. Since nectar microbes are primarily flower-visitor dispersed, they have great potential to affect and be affected by flower visitor network structure. However, the interactions of plants with their flower visitors and nectar microbes have yet to be considered in a network framework. The aim of this project is to test the hypothesis that hub plant species (plant species that have very high diversity of flower visitors) are also hubs of floral microbe diversity and dispersal in a native plant community. Network hubs are known to be responsible for a disproportionate amount of pathogen spread within animal species ("super-spreaders"). In flower visitor networks, hub plant species might function as super-spreaders of floral microbes between plant species. The project goals are to construct a dataset of plants, their flower visitors, and nectar microbe composition as well as perform a manipulative experiment on a species with high variation in flower visitors, Aquilegia formosa, in a high elevation wet meadow plant community. Simulation models will be used to evaluate the effects of visitor diversity and visitation frequency on the diversity of nectar microbes at the plant level. The researchers will empirically test the hypothesis that certain flowers are hubs of nectar microbe diversity.