Data and Code for: Resistance is futile: Weaker selection for resistance by abundant parasites increases prevalence and depresses host density

We model host evolution of costly resistance to infection and its dependence on environmental factors, such as nutrients. We find that higher nutrients can increase infection prevalence AND select for lower resistance. In turn, the model predicts that lower resistance drives infection prevalence even higher while depressing host density. The attached code performs the model analysis, produces the published figures, and conducts statistical analysis on the data (described below). We conducted a mesocosm experiment with mixtures of zooplankton host (Daphnia dentifera) genotypes, algal resources (Ankistrodesmus falcatus), and fungal parasites (Metschnikowia bicuspidata). Mesocosm populations were supplied with low or high nutrients (5 or 50 ug/L phosphorus and 100 or 1000 ug/L nitrogen). We measured densities of hosts along with age class (juvenile or adult), sex, infections status, and egg number and chlorophyll densities; these data are a subset of data published previously Walsman et al..., ,

本研究构建了宿主对感染的代价性抗性演化模型，并分析其对营养等环境因子的依赖性。研究发现，更高的营养水平可提升感染率，同时筛选出更低的抗性水平。该模型进一步预测，更低的抗性水平会进一步推高感染率，同时降低宿主种群密度。随附代码可完成模型分析、生成已发表的图表，并对下述数据开展统计分析。本研究开展了一项中型实验生态系统（mesocosm）实验，实验体系包含浮游动物宿主齿纹溞（Daphnia dentifera）的不同基因型、藻类食物资源镰形纤维藻（Ankistrodesmus falcatus）以及真菌寄生虫双突梅奇酵母（Metschnikowia bicuspidata）的混合群落。中型实验生态系统种群分别施加低营养或高营养水平处理（磷浓度为5或50 μg/L，氮浓度为100或1000 μg/L）。我们测定了宿主种群密度，同时记录了宿主的年龄阶层（幼体或成体）、性别、感染状态、产卵量以及叶绿素密度；本数据集为Walsman等人此前发表的研究数据的子集。