DISSERTATION RESEARCH: Elucidating the Roles of Abiotic and Biotic Factors in Exotic Species Establishment: A Trait-based Approach

非本地物种的入侵是21世纪最大的环境挑战之一，不仅威胁到本地动植物及其提供的生态系统服务，还威胁到农业、人类健康和经济。非本地物种的入侵和建立受到物理（非生物）因素（如温度）和与本地物种（生物因素）的相互作用（如捕食和竞争）的驱动。了解这些生物和非生物因素如何相互放大或抵消，对于预测入侵物种在新地区建立的条件，以及制定控制这些物种扩散的方法是必要的。然而，大多数研究忽视了非生物和生物因素对入侵成功的共同影响，因为它们只研究了一种因素。这个项目通过研究环境温度和资源竞争对加利福尼亚昆虫入侵的共同影响来解决这个问题。这项研究结合了实验室实验、实地观察和数学模型来预测允许入侵物种传播的条件。目前，美国每年花费数亿美元用于控制入侵物种。该项目旨在通过提供制定更具成本效益的控制措施所需的科学知识来降低这一成本。该项目综合了操作实验、实地观察和数学模型，以研究温度和竞争如何影响一对生态相关昆虫的种群动态和物种相互作用，一种是本地昆虫，一种是入侵昆虫。这项工作的动力来自于加利福尼亚沿海鼠尾草灌丛群落中发生的一种本地入侵相互作用，在这种相互作用中，两种半足纲动物（科：五足科），本地的Murgantia histrionica和最近的北美入侵Bagrada hilaris，竞争它们的主要宿主，多年生灌木Cleome isomeris。本研究旨在(i)量化温度和密度对两种物种生活史特征（繁殖力、发育和死亡率）的共同影响，（ii）参数化阶段结构种群动态的数学模型，该模型包含了生命速率温度响应的机制描述，以及由温度变化引起的时间依赖性发育延迟。这些目标是通过(i)密度和温度处理的全因子实验室实验实现的，（ii）使用应用于实验数据的最大似然方法估计模型参数，用于分析种群动态的延迟微分方程模型，以及（iii）实地收集昆虫丰度以测试模型的预测。

Invasions of non-native species are one of the greatest environmental challenges of the 21st century, threatening not only native flora, fauna, and the ecosystem services that they provide, but also agriculture, human health, and the economy. Invasion and establishment of non-native species is driven by both physical (abiotic) factors, such as temperature, and by interactions with native species (biotic factors), such as predation and competition. Understanding how these biotic and abiotic factors magnify or cancel one another is necessary for forecasting the conditions under which invasive species establish in new localities, and for developing methods to control the spread of such species. Yet, most studies overlook the joint effects of abiotic and biotic factors on invasion success because they examine on only one type of factor. This project addresses this problem by examining the joint effect of environmental temperature and competition for resources on invasion by an insect in California. The research combines laboratory experiments, field observations, and mathematical models to forecast the conditions that allow the invasive species to spread. Currently, the U.S. spends hundreds of millions of dollars annually on invasive species control. This project aims to reduce this cost by providing the scientific knowledge needed to develop more cost-effective control measures.The project integrates manipulative experiments, field observations and mathematical models to examine how temperature and competition impact population dynamics and species interactions of an ecologically related pair of insects, one native and one invasive. The impetus for this work comes from a native-invasive interaction occurring in the California coastal sage scrub community in which two Hemipterans (Family: Pentatomidae), native Murgantia histrionica and recent North American invasive Bagrada hilaris, compete for their primary host, the perennial shrub Cleome isomeris. This study aims to (i) quantify the joint effect of temperature and density on life history traits (fecundity, development, mortality) of the two species, and (ii) parameterize a mathematical model of stage-structured population dynamics that incorporates mechanistic descriptions of vital rate temperature responses, and time-dependent developmental delays that arise due to temperature variation. These goals are achieved through (i) a fully factorial lab experiment with density and temperature treatments, (ii) estimation of model parameters using maximum likelihood methods applied to experimental data, which are used to analyze a delay differential equation model of population dynamics, and (iii) field collection of insect abundances to test the model's predictions.