Host virus coevolution – demography versus selection in the face of multiple stressors

人们一直有兴趣描述适应性进化的速度，并需要更好地了解影响进化速度的因素。特别是，我们缺乏对基因组水平上的进化动力学如何与在复杂环境中共同进化的种群的适应度分布相关的详细了解。在这里提出的项目中，我们的目标是识别共同进化的宿主病毒群体中的快速适应性基因组变化，并确定宿主和病毒的多重应激源如何改变快速适应的速度和轨迹。在以前的实验中，结合基因组分析，我们展示了宿主的人口统计变化以及宿主和病毒之间的共同进化如何影响宿主和病毒在基因组水平上的适应性变化。使用相同的实验系统和前一个项目中开发的生物信息学工具，我们现在的目标是检验非生物应激源和物种相互作用交互作用影响适应性进化速度的假设。我们将在多个水平上跟踪随时间变化的动态，即种群动态、表型和基因组变化，并在表型水平(时移实验)和基因组水平(全基因组关联)详细描述观察到的数百(840)个藻类克隆的变化。我们将明确测试病毒和/或宿主的额外非生物应激源是否会直接(I)通过改变选择的强度和方向性，(Ii)通过不同个体之间的相互作用(克隆干扰)，(Iii)通过基因组内的相互作用(多位性，上位性)，或(Iv)通过人口统计学的变化间接改变共同进化动力学。总体而言，我们将确定非生物应激源引入的环境复杂性是否以及如何限制抗性进化的步伐，即使在突变率很高的情况下也是如此。

There is a continuing interest to characterise the pace of adaptive evolution and a need for a better understanding of the factors influencing the rate of evolution. Especially, we lack a detailed understanding on how evolutionary dynamics at the genomic level relate to the distribution of fitness in populations evolving together in complex environments. In the project proposed here, we aim to identify rapid adaptive genomic changes in coevolving host-virus populations and to determine how multiple stressors for the host and virus alter the rate and trajectory of rapid adaptation. In previous experiments combined with genomic analyses we showed how demographic changes of host and coevolution between the host and virus affected adaptive changes at the genome level of both, host and virus. Using the same experimental system and the bioinformatics tools developed in the previous project, we now aim testing the hypothesis that abiotic stressors and species interactions interactively affect the pace of adaptive evolution. We will follow the dynamics of changes across time at multiple levels, i.e. population dynamics, phenotypic and genomic changes and characterise observed changes across a few hundred (840) algae clones in detail at the phenotype level (time shift experiments) and at the genome level (genome-wide associations). We will explicitly test if additional abiotic stressors for virus and/or host will alter the coevolutionary dynamics directly (i) through altering the strength and directionality of selection, (ii) through interactions between different individuals (clonal interference), (iii) through interactions within the genome (pleitropy, epistasis), or (iv) indirectly through demographic changes. Overall we will identify if and how environmental complexity introduced by abiotic stressors constrains the pace of resistance evolution even when the mutation rate is high.