Dissertation Research: Causes of Complex Dynamics in Cardamine Pensylvanica Populations

本项目是对宾夕法尼亚小豆豆（Cardamine pennsylvania）种群动态机制的研究。在早期的研究中，这些植物的实验种群在15代内表现出复杂的数值动态，种群在3到4代内从低密度到高密度循环。虽然密度依赖的种群增长的简单模型预测振荡动力学是可能的，但这些模型在应用于我们的实验种群时预测了稳定（非循环）动力学。这个项目将调查造成模型预测和观测到的动态之间差异的因素。由此，研究人员推断出类似的机制何时可能在自然种群中驱动复杂的动态。自然界中复杂动力学的意义是双重的。首先，如果这些动态是确定性种群调节的产物（相对于资源可用性的随机波动），那么试图解释自然的复杂性应该集中在理解驱动这些过程的反馈机制上。其次，由于人口统计的随机性，人口规模高度可变的群体容易灭绝，并且由于随机遗传变化的概率增加，可能无法适应不断变化的环境。因此，了解种群动态对于解释基础生态研究和环境管理至关重要。t vv !!!F v v (Times New Roman Symbol & Arial 1 " h * eX* eX* e 9 7 Crystal Blackshear水晶Blackshear

9321790 Antonovics This project is an investigation of the mechanisms governing population dynamics in Cardamine pennsylvanica, a weedy plant. In an earlier study, experimental populations of these plants displayed complex numerical dynamics over fifteen generations, with populations cycling from low to high density in three to four generations. Although simple models of density-dependent population growth predict that the oscillatory dynamics are possible, these models predicted stable (non-cyclic) dynamics when applied to our experimental populations. This project will investigate what factors responsible for the discrepancy between the model predictions and the observed dynamics. From this, the investigators extrapolate to when similar mechanisms might drive complex dynamics in natural populations. The significance of complex dynamics in nature is twofold. First, if these dynamics are the product of deterministic population regulation (as opposed to stochastic fluctuations in resource availability), then attempts to interpret the complexity of nature should focus on understanding the feedback mechanisms that drive these processes. Second, populations that are highly variable in size are prone to extinction due to demographic stochasticity, and may be unable to adapt to a changing environment due to increased probability of random genetic change. Thus, an understanding of population dynamics is crucial to interpreting basic ecological studies, as well as to environmental management. t v v ! ! ! F v v ( Times New Roman Symbol & Arial l " h * eX* eX* e 9 7 Crystal Blackshear Crystal Blackshear