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首页> 外文学位 >Investigation of Three Species Predator-Prey Food Chain Model in Ecology: 'Ecological' Damping, Allee Effects and Environmental Noise.
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Investigation of Three Species Predator-Prey Food Chain Model in Ecology: 'Ecological' Damping, Allee Effects and Environmental Noise.

机译：三种生态系统中的捕食者－猎物食物链模型的研究：“生态”阻尼，阿利效应和环境噪声。

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摘要

Invasive species are defined as any species capable of propagating into a nonnative environment. If established, they can be extremely difficult to eradicate, or even manage. In this thesis, we developed and analyzed a mathematical model of biological control to prevent or attenuate the explosive increase of an invasive species population, that functions as a top predator, in a three species food chain. We incorporated controls that were shown to drive down the invasive population growth and, in certain cases, eliminated explosion. Hence, the population did not reach an uncontrollable level. We referred to these new controls as "ecological damping", as their inclusion dampens the invasive species population growth. We again investigate the effect of random environmental fluctuation on such explosive growth of the invasive species. We find that environmental noise alone, cannot prevent explosive growth in invasive populations. We interpret these results as showing that invasive species can strongly adapt to a randomly changing environment.;We investigated an important phenomenon known as Allee effect in a three species food chain model. Allee effect is phenomenon characterized by positive density dependence, that is a positive correlation between population density and individual fitness. However, the effect is not well studied in multi-level trophic food chains. We therefore considered a ratio dependent spatially explicit three species food chain model, where the top predator is subjected to a strong Allee effect. Next, we numerically investigated the decay rate to a target attractor. We found decay estimates that are O(mgamma), where gamma was found explicitly to be close to 1.0. Furthermore, we provided overexploitation theorems for the food chain model, showing that overexploitation has to be driven by the middle predator. In particular overexploitation is not possible without an Allee effect in place. We also uncovered a rich class of Turing patterns in the model which depend significantly on the Allee threshold parameter m..
机译：入侵物种定义为能够繁殖到非本地环境中的任何物种。如果建立起来，它们将很难根除甚至管理。在本文中，我们开发并分析了生物控制的数学模型，以防止或减弱三物种食物链中作为顶级掠食者的入侵物种种群的爆炸性增长。我们采用了能够降低入侵种群增长并在某些情况下消除爆炸的控制措施。因此，人口并没有达到无法控制的水平。我们将这些新控件称为“生态阻尼”，因为它们的包含会抑制入侵物种的数量增长。我们再次调查随机环境波动对这种入侵物种的爆炸性增长的影响。我们发现仅靠环境噪声并不能阻止入侵人群的爆炸性增长。我们将这些结果解释为表明入侵物种可以强烈适应随机变化的环境。我们研究了一种在三物种食物链模型中被称为Allee效应的重要现象。 Allee效应是一种以正密度依赖性为特征的现象，即人口密度与个体适应性之间呈正相关。但是，在多级营养食物链中对这种作用的研究还不够好。因此，我们考虑了比率依赖的空间显性三物种食物链模型，其中顶级捕食者受到强烈的阿利效应。接下来，我们通过数值研究了目标吸引子的衰减率。我们发现衰减估计为O（mgamma），其中gamma被明确确定为接近1.0。此外，我们为食物链模型提供了过度开发定理，表明过度开发必须由中间捕食者驱动。特别是如果没有Allee效应，就不可能进行过度开发。我们还在模型中发现了丰富的Turing模式类别，这些模式很大程度上取决于Allee阈值参数m。

著录项

  • 作者

    Quansah, Emmanuel Kwesi-Amonoo.;

  • 作者单位

    Clarkson University.;

  • 授予单位 Clarkson University.;
  • 学科 Mathematics.;Bioinformatics.;Biology.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 235 p.
  • 总页数 235
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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