C-RUI: Spatial Modeling of a Biological Invasion: the Spread of Sudden Oak Death and the Importance of Host Genetics, Environmental Forcings, and Community Structyre

生物入侵是全球环境变化的一个重要组成部分。入侵可能导致生物多样性减少，并常常导致生态系统的永久性改变。入侵的非本地植物病原体对世界许多地区的生态系统产生了巨大影响。这些病原体的扩散机制及其生态后果是保护和生态系统管理的关键问题。空间格局是疾病动力学的基本属性，因为它反映了遗传异质性和环境力量对病原体传播和生活史的影响。需要多学科方法来解决以下挑战：1)将病原体扩散的精细尺度过程纳入景观水平模型；2)将环境因素和宿主种群遗传学与疾病发病率的空间变化结合起来。在这篇论文中，我们描述了一项研究，分析了疫霉（phytophthora ramorum）的时空动态，疫霉是一种新兴的，可能是外来的病原体，导致加利福尼亚沿海的橡树和tanoaks致命疾病。这种疾病被称为橡树猝死病（SOD），在几个县已经达到流行病的程度。该方案将寄主遗传、群落结构和环境变化的空间数据与研究ramorum传播机制相结合，以模拟该植物病害在景观中的分布变化。模型预测将确定影响超氧化物歧化酶分布的关键因素，并提供超氧化物歧化酶导致橡树林地栖息地丧失的预测。该提案描述了一个多学科的项目，以模拟破坏性植物疾病的传播并预测其生态后果。我们的目标不是为单个研究人员开发的离散活动，而是研究人员之间的合作努力来解决单个问题。我们的目标是：1。根据几个关键环境因素之间的关系，开发一个基于统计的模型，预测景观中SOD风险的空间格局。这些因素包括与以前感染地点的接近程度、宿主物种的遗传背景、植物群落结构、景观结构、非生物条件和人为活动。2 .在精细空间尺度和有利于病原体繁殖和扩散的环境条件下，基于病原体在宿主之间传播的实证研究，建立预测病原体活动和宿主易感性空间格局的机制模型。建立一个SOD扩散模型，该模型集成了统计模型和机制模型中最具预测性的组成部分。促进本科生参与这项跨学科研究，并将研究纳入索诺玛州立大学生物系和地理系的核心课程。索诺玛州立大学距离学习区不到20公里，PI和他们的学生都很容易到达。先前对环境变化与SOD传播之间关系的分析集中在Marin县受影响最严重的地区，在那里病原体感染了整个研究区域的树木。相比之下，目前的研究侧重于SOD扩散到目前没有感染迹象的新区域。我们相信，这种方法将大大有助于更好地了解这种病原体的生物学，以及我们对植物-病原体相互作用的生态学和遗传学的理解。这项研究的时间安排也将确保索诺玛州立大学的本科生积极参与，他们希望参与每个人都认识到对更大的社区至关重要的研究。

Biological invasions represent a major component of global environmental change.Invasions may lead to reduced biodiversity and often result in permanent alterations toecosystems.Invasive non-native plant pathogens have dramatically affected ecosystems in manyparts of the world.The mechanisms underlying dispersal of these pathogens and their ecologicalconsequences are critical issues for conservation and ecosystem management.Spatial pattern isa fundamental property of disease dynamics because it reflects the genetic heterogeneity andenvironmental forces acting on pathogen dispersal and life history.A multidisciplinary approachis required to solve the challenges of 1)incorporating fine-scale processes of pathogen dispersalinto landscape-level models and 2)integrating spatial variation in environmental factors and hostpopulation genetics with disease incidence.In this proposal,we describe research to analyze spatio-temporal dynamics ofPhytophthora ramorum,an emerging,and probably exotic,pathogen that causes a lethal diseaseof oaks and tanoaks in coastal California.This disease,known as Sudden Oak Death (SOD),hasreached epidemic levels in several counties.The proposal integrates spatial data on hostgenetics,community structure,and environmental variation with investigations of mechanismsunderlying spread of P.ramorum to model changes in the distribution of this plant disease acrossthe landscape.Model predictions will identify critical factors that influence the distribution ofSOD and provide forecasts of habitat loss in oak woodlands as a consequence of SOD.Thisproposal describes a multidisciplinary program to model the spread of a destructive plant diseaseand to predict its ecological consequences.Our objectives are not developed as discreteactivities for individual researchers,but rather a collaborative effort among researchers to attacka single problem.We aim to accomplish the following:1.Develop a statistically based model that predicts spatial patterns of SOD risk on thelandscape,based on relationships among several critical environmental factors.These factorsinclude proximity to previously infected locations,genetic background of host species,plantcommunity structure,landscape structure,abiotic conditions,and anthropogenic activities.2.Develop a mechanistic model that predicts spatial patterns of pathogen activity and hostsusceptibility based on empirical studies of pathogen dispersal between hosts on fine spatialscales and on environmental conditions conducive to pathogen reproduction and dispersal.3.Develop a model of SOD spread that integrates the most predictive components of thestatistical and mechanistic models.4.Foster participation of undergraduates in this cross-disciplinary research and integrate theresearch into the curriculum of core courses in the Departments of Biology and Geography atSonoma State University.Sonoma State University is located within 20 km of the study area,which is easilyaccessible to PI s and their students.Previous analyses of the relationship betweenenvironmental variation and SOD spread have concentrated on the most heavily impactedregions in Marin County where the pathogen has infected trees throughout the study area.Incontrast,the present study focuses on SOD spread into new areas that presently show no sign ofinfection.We believe that this approach will contribute substantially towards a greaterunderstanding of the biology of this pathogen and to our understanding of the ecology andgenetics of plant-pathogen interactions.The timing of this study will also ensure involvement bymotivated undergraduates at Sonoma State University who wish to participate in research thateveryone recognizes is of critical significance to the larger community.