Ecoevolutionary feedbacks of phenotypic plasticity and mono- vs polyclonal communities in bi- and tritrophic systems

我们的项目将重点研究个体性状变异（表型可塑性）和遗传性状变异（多克隆系统）对双营养和三营养系统中以藻类为食物，草食性纤毛虫为主要消费者及其纤毛虫捕食者的种群，群落和性状动态的影响。在我们的系统中，表型可塑性在两个营养水平上起作用。纤毛虫（Euplotes aiculatus和E. occarinatus）可以形成表型上的可塑性防御来对抗它们的捕食者，这包括防御和竞争力量之间的权衡。此外，我们将在单克隆和多克隆实验中使用不同的Euplotes菌株，这些菌株的可塑性、生长速度和竞争强度的反应规范不同。因此，我们通过可塑性和克隆组成的变化来研究性状变异。此外，我们将使用能够形成诱导进攻的捕食者（Lembadion bullinum），这在一定程度上允许克服猎物的防御，或者捕食者，它们对猎物的防御没有反应（Stenostomum sphagnetorum）。在我们的系统中，我们将解决以下假设：在不同的无性系中，在消费水平上以克隆特异性反应规范（表型可塑性）表达的性状变异促进了三营养系统中营养水平的稳定性和持久性。2. 与单克隆系统相比，具有克隆特异性反应规范的多克隆消费者系统提高了群体的稳定性。根据调整的相对速度，在三营养系统中，消费者营养水平上的性状变异比两个营养水平（消费者和顶级捕食者）上的性状变异更能稳定营养动力学。我们的项目将结合实证实验和数学建模方法。它与SPP的其他项目密切相关，但独特之处在于我们研究了一个三营养系统，在这个系统中，捕食者对猎物的诱导防御形成诱导进攻。我们的项目将促进对生态过程的理解，特别是对捕食者-猎物和食物网动态的理解。

Our project will focus on the effects of individual trait variation (phenotypic plasticity) and genetic trait variation (polyclonal systems) on population, community and trait dynamics in bi- and tri-trophic systems with algae as food, herbivorous ciliates as primary consumer and their ciliate predators. In our system phenotypic plasticity acts on two trophic levels. The ciliates (Euplotes aediculatus and E. octocarinatus) can form phenotypically plastic defences against their predators, which includes a trade-off between defence and competitive strength. Furthermore, we will use different Euplotes strains that differ in their reaction norms of plasticity, growth rates and competitive strength in mono- and polyclonal experiments. Consequently, we study trait variation via plasticity and via shifts in the clonal composition. Additionally, we will use predators that can form inducible offences (Lembadion bullinum), which partly allow to overcome the prey defences, or predators, which do not respond to the prey defences (Stenostomum sphagnetorum). With our system we will address the following hypotheses:1. Trait variation expressed in clone-specific reaction norms (phenotypic plasticity) in different clones on the consumer level promotes the stability and persistence of trophic levels within a tri-trophic system. 2. Polyclonal consumer systems with clone-specific reaction norms of traits increase population stability compared to monoclonal systems.3. Trait variation on the consumer trophic level may stabilize trophic dynamics more than trait variation on two trophic levels (consumer and top predator) within a tri-trophic system depending on the relative speeds of adjustment.Our project will combine empirical experiments and mathematical modelling approaches. It is closely linked to other projects in the SPP but is unique in that we study a tri-trophic system where the predator forms inducible offenses in response to its prey’s inducible defences. Our project will foster the understanding of ecological processes in general and of predator-prey and food web dynamics in particular.