DISSERTATION RESEARCH: Network heterogeneity and metapopulation persistence in Pseudomonas syringae

社会越来越多地被网络所定义——由或大或小的距离分开的个人组成的群体。跨空间的移动决定了网络的强度、信息传播的速度（社会网络）或个人互动的速度（人口网络），以及一个群体中的事件对另一个群体的影响程度。该项目将使用一种新工具来确定种群之间的联系如何、何时以及为何决定一个种群是持续存在还是灭绝。该项目的结果将改善因土地使用变化而日益孤立的人口的养护和管理计划。改善保护计划对于在脆弱的生态网络中持续存在的濒危物种尤为重要。该项目将促进一名博士生的培训和教育，该博士生已经开发并将改进一种新的实验工具。研究人员将使这一工具的设计和使用可公开获取，促进研究人员共同设计和共享设备的民主科学进程。这种研究方法的使用将通过提供有监督的独立研究的项目扩展到本科生和中学生。该项目将使用新开发的实验室直接测试现有元人口模型的假设和预测；元种群是由相互关联的种群组成的群体。在室中培养的细菌群将通过走廊以均匀晶格或强烈异质排列相连。殖民化和灭绝的速度都可以通过控制廊道结构和四环素干扰种群来控制，从而导致灭绝。这些操作将比较斑块占用和超种群持久性在同质和异质网络在灭绝-殖民化比率的梯度。研究人员下一步将设计符合晶格、随机、指数和幂律分布的网络处理方法，以确定细菌种群无法继续存在的灭绝与定植比的阈值。最后的操作将创建连接到单个邻居的“孤独”种群，并将种群持久性与连接到网络中不同节点的对应种群进行比较。这些实验将提高对空间异质性对生态和进化过程的影响的理解，并确定由强网络和弱网络组成的元种群的适当保护策略。

Society is increasingly defined by networks - groups of individuals separated by small or large distances. Movement across space to connect groups determines the strength of a network, the rates at which information spreads (social networks) or individuals interact (population networks), and the extent to which events in one group affect events in another group. This project will use a new tool to determine how, when, and why connections among populations determine whether a population persists or goes extinct. Results of the project will improve conservation and management plans for populations that are increasingly isolated by changes in land use. Improved conservation plans will be particularly important for endangered species that persist within weak networks. The project will advance the training and education of a doctoral student, who has developed and will improve a new experimental tool. Investigators will make the design and use of this tool publicly accessible, contributing to a democratic scientific process in which researchers co-design and share equipment. Use of this research approach will be extended to undergraduate and middle school students through programs that provide supervised independent research.This project will use a newly-developed experimental chamber to test directly both assumptions and predictions of existing metapopulation models; metapopulations are groups of linked populations. Bacterial populations cultured in chambers will be connected by corridors in a homogeneous lattice or a strongly heterogeneous arrangement. Both colonization and extinction rates will be controlled by manipulating corridor configurations and by disturbing populations with tetracycline, causing extinction. These manipulations will compare patch occupancy and metapopulation persistence in homogenous and heterogeneous networks across a gradient of extinction-to-colonization ratios. The researchers will next design network treatments that conform to lattice, random, exponential, and power-law distributions to identify the threshold extinction-to-colonization ratio at which bacterial populations can no longer persist. A final manipulation will create 'lonely' populations that are connected to a single neighbor and compare population persistence to that of counterpart populations connected to diverse nodes in a network. These experiments will improve understanding of the effects of spatial heterogeneity on ecological and evolutionary processes and identify appropriate conservation strategies for metapopulations comprising strong versus weak networks.