Trait heterogeneity effects on trophic interactions: the role of essential nutrients

食物质量取决于猎物体内必需资源的可得性，对捕食者的生理、行为和生活史性状有很大影响。该项目的目标是将这种食品质量效应整合到性状变异的最新方法中。我们将评估食物质量和相关的反馈机制在形成性状异质性和捕食者与猎物之间复杂和动态的相互作用中的作用。特别是，我们希望通过研究双营养模式系统的种间性状变异和三营养模式系统的种内捕食来估计种群动态和物种共存。采用实验和理论相结合的方法，我们正在研究由轮虫捕食者和两种食物质量（就必需脂质而言）差异很大的猎物组成的化学调节系统中简单的、人工组装的、因此高度易处理的食物网。我们假设生化营养的限制主要影响捕食者对猎物的利用效率（从而影响其数值反应和生长速度），而不是使猎物免于被捕食，因为这是低适口性的情况。由于低质量猎物的利用取决于高质量猎物的可用性和捕食者的生理反应，因此营养相互作用和种群密度可能是高度动态的，导致营养水平之间存在重要的反馈回路。随后，将探索更复杂的食物网，例如，考虑到猎物物种之间防御能力的潜在差异以及其他中间食草动物（公会内捕食）的存在。人口/社区动态将通过迭代使用数学模型和实验进行调查。了解基本营养物质在塑造种群动态方面的潜力，对于预测种群和食物网如何应对不断变化的环境条件至关重要。

Food quality depends on the availability of essential resources in the prey and has great impacts on physiological, behavioral and life history traits of predators. The objective of the project is to integrate such food quality effects into recent approaches on trait variation. We will assess the role of food quality and associated feedback mechanisms in shaping trait heterogeneity and the complex and dynamic interactions between predator and prey. In particular, we want to estimate population dynamics and species coexistence by studying interspecific trait variation in bi-trophic model systems and intraguild predation in tri-trophic model systems. Using a combined experimental and theoretical approach, we are studying simple, manually assembled and therefore highly tractable food webs in chemostat systems consisting of a rotifer predator and two prey species substantially differing in food quality (in terms of essential lipids). We assume that a limitation by biochemical nutrients will mainly affect the prey utilization efficiency of the predator (and thus its numerical response and growth rate), but not saving the prey from predation as this is the case for low palatability. As the utilization of the low quality prey depends on the availability of the high quality prey and the physiological response of the predator, trophic interactions and population densities can be highly dynamic, resulting in important feedback loops between trophic levels. Subsequently, food webs of higher complexity will be explored, considering, for instance, potential differences in defense capacities among prey species and the presence of additional intermediary grazers (intra-guild predation). The population/community dynamics will be investigated by iteratively using mathematical models and experiments. Understanding the potential of essential nutrients in shaping population dynamics is crucial for predicting how populations and food webs will respond to changing environmental conditions.