Consumer diversity effects in multispecies predator-prey systems: Relevance of inter- and intraspecific consumer trait variation

鉴于全球物种的急剧减少，许多生态学研究已经解决了生物多样性丧失对生态系统功能的影响，最近也在多营养背景下进行了研究。消费者多样性对食物网动态的影响高度依赖于环境，并由食物网配置决定，涉及物种特异性特征，如消费者专业化和放牧率。生物的功能特征和相关的权衡被认为对生态系统的功能起着关键作用。该项目旨在通过实验室实验和基于过程的模型相结合的方法，评估性状变异在两个相互作用的营养水平上的作用，以了解消费者多样性丧失对营养动力学和生态系统功能的影响。我们将使用淡水纤毛虫消费者和微藻猎物作为模型系统，这使我们能够特别关注消费者特定的特征和权衡，例如消费者专业化（通才vs专家），放牧和生长速度（权衡：专业化vs放牧效率）以及相关的猎物特征变化（可食性vs生长速度）。在纤毛虫微藻系统的实验室实验中，将研究在依赖于猎物组成和其他纤毛虫竞争对手的情况下，种间和种内消费性状的变化，以及长期种群动态（25至40代）和相互作用的营养水平之间的反馈循环。实验数据将用于校准和验证一个多物种模型，这将有助于确定驱动实验中观察到的关于种群动态、群落变异和性状变异（即功能多样性）维持模式的机制。同时，模型仿真将用于优化后续实验的实验设计。这种联合方法将扩大现有的多物种食物网性状动力学的实验和理论知识，并将大大提高我们对生物多样性丧失对营养动力学和生态系统功能的影响的理解。

Given the dramatic global loss of species, numerous ecological studies have addressed the consequences of biodiversity loss on ecosystem functioning, more recently also in a multitrophic context. Consumer diversity effects on food web dynamics were shown to be highly context-dependent and determined by the food web configuration, involving species-specific traits, such as consumer specialization and grazing rates. The functional traits of organisms and associated trade-offs are supposed to play a key role for ecosystem functioning. The proposed project aims at evaluating the role of trait variation on two interacting trophic levels for understanding the consequences of consumer diversity loss on trophic dynamics and ecosystem functioning in a joint approach combining laboratory experiments with a process-based model. We will use freshwater ciliate consumers and microalgal prey as a model system, which allows us to focus particularly on consumer specific traits and trade offs, such as consumer specialization (generalists versus specialists), grazing and growth rates (trade off: specialization versus grazing efficiency) and the associated prey trait variation (edibility versus growth rate). Laboratory experiments on a ciliate microalgae system will investigate the inter- and intraspecific consumer trait variation in dependence of prey composition and the presence of other ciliate competitors as well as long-term population dynamics (25 to 40 generations) and feedback loops among interacting trophic levels. Experimental data will be used to calibrate and validate a multispecies model, which will help to identify the mechanisms driving the observed patterns in experiments regarding population dynamics, community variability and the maintenance of trait variation (i.e. functional diversity). At the same time, model simulations will be used to optimize the experimental design of subsequent experiments. This joint approach will broaden the existing experimental and theoretical knowledge on trait dynamics in a multispecies food web and will substantially enhance our understanding of the consequences of biodiversity loss on trophic dynamics and ecosystem functioning.