Dissertation Research: The Roles of Local and Metapopulation Forces in Determining Regional Scale Aphid Population Dynamics

许多生物的活动范围是由通过迁徙而连接在一起的适宜生境斑块上的种群集合组成的。这样的集合被称为元种群。为了理解和预测元种群在一段时间内的行为，有必要分别了解影响每个种群的过程（例如，捕食者-猎物关系）和影响斑块之间迁移的过程。对黄斑蚜虫（Aphis lugentis）的初步研究表明，捕食压力和斑块分布都影响着超种群动态。两年多来收集的观测和实验数据被用来拟合一个描述lugentis系统的模拟模型。该模型将用于预测将在野外进行的大规模捕食者密度和斑块排列操作的结果。提出的操作将是第一个明确的实验测试的作用迁移在控制元种群动态。当仿真模型能够准确地预测大规模操作的结果时，它将用于回答两个密切相关的问题。首先，在什么条件下影响斑块间迁移的因素在元种群动态中发挥重要作用？第二，在什么条件下，斑块内的过程变得如此重要，以至于掩盖了决定元种群动态的迁移影响？这项研究将为迁移在确定超种群动态中的重要性提供关键的实验证据。虽然大量的理论预测了迁移率在决定元种群动态方面的关键作用，但这一理论在很大程度上尚未得到验证。然而，元种群模型在物种管理和保护计划中被广泛使用。除了提供实验证据证明迁移确实在确定元种群动态方面发挥重要作用外，本研究还将探讨斑块内过程和迁移的相对重要性在各种条件下如何变化。在这样做的过程中，它将在预测何时可以仅根据斑块内部过程的信息、仅根据迁移和灭绝率的信息来预测大规模种群动态，以及何时需要两个尺度上的更详细的信息方面迈出一大步。

Morris9801089The range of many organisms consists of collections of populations in suitable habitat patches connected through migration. Such collections are called metapopulations. In order to understand and predict how metapopulations will behave over time it is necessary to understand both processes affecting each of the populations separately (e.g. predator-prey relations) and processes affecting migration between patches. Preliminary studies on the aphid, Aphis lugentis, reveal that both predation pressure and patch distribution affect metapopulation dynamics. Observational and experimental data collected over two years is being used to fit a simulation model describing the A. lugentis system. The model will be used to predict the results of large-scale manipulations of predator density and patch arrangement which will be carried out in the field. The proposed manipulations will be the first explicit experimental test of the role of migration in controlling metapopulation dynamics. When the simulation model is able to accurately predict the results of the large-scale manipulations it will be used to answer two closely related questions. First, under what conditions do factors affecting migration between patches play an important role in metapopulation dynamics? Second, under what conditions do within patch processes become so important as to mask the affects of migration in determining metapopulation dynamics? This study will provide crucial experimental evidence for the importance of migration in determining metapopulation dynamics. While a great deal of theory predicts a critical role for migration rates in determining metapopulation dynamics that theory has gone largely untested. Nevertheless metapopulation models are widely used in species management and conservation plans. Beyond providing experimental evidence that migration does indeed play an important role in determining metapopulation dynamics, this study will explore how the relative importance of within patch processes and migration change under a variety of conditions. In so doing it will take a large step towards predicting when large-scale population dynamics can be predicted based on information about within patch processes alone, migration and extinction rates alone, and when more detailed information at both scales is necessary.