Indirect effects, both density- and trait-mediated, have been known to act in tandem with direct effects in the interactions of numerous species. They have been shown to affect populations embedded in competitive and mutualistic networks alike. In this work, we introduce a four-dimensional system of ordinary differential equations and investigate the interplay between direct density-effects and density- and trait-mediated indirect effects that take place in a yeast parasite-zooplankton host-incompetent competitor system embedded in a food web which also includes resources and predators. Among our main findings is the demonstration that indirect effects cause qualitative and quantitative changes almost indistinguishable from direct effects and the corroboration through our analysis of the fact that the effects of direct and indirect mechanisms cannot be disentangled. Our results underpin the conclusions of past studies calling for comprehensive models that incorporate both direct and indirect effects to better describe field data.

中文翻译：

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对浮游疾病系统的间接影响。

众所周知，密度和性状介导的间接作用在许多物种的相互作用中与直接作用协同作用。事实证明，它们会影响嵌入竞争和互惠网络的人口。在这项工作中，我们介绍了一个常微分方程的四维系统，并研究了直接密度效应与密度和性状介导的间接效应之间的相互影响，这种效应发生在嵌入在酵母中的酵母寄生虫-浮游动物宿主无能竞争者系统中食物网，其中还包括资源和捕食者。在我们的主要发现中，有一个论证表明，通过对直接和间接机制的影响无法加以分解的事实的分析，间接影响会导致定性和定量变化几乎与直接影响和佐证没有区别。我们的研究结果支持了以往研究的结论，这些研究要求建立综合模型，将直接和间接影响结合起来，以更好地描述现场数据。