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丧失，许多生态学研究探讨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探讨了这一问题。消费者多样性对食物网动态的影响被证明是高度依赖于上下文的，并由食物网配置，涉及物种特有的特征，如消费者专业化和放牧率。生物体的功能特征和相关的权衡被认为对生态系统的功能发挥关键作用。拟议的项目旨在评估性状变异对两个相互作用的营养水平的作用，以了解消费者多样性丧失对营养动态和生态系统功能的影响，采用实验室实验与基于过程的模型相结合的联合方法。我们将使用淡水纤毛虫消费者和微藻猎物作为一个模型系统，这使我们能够特别关注消费者的具体特征和权衡，如消费者专业化（通才与专家），放牧和增长率（权衡：专业化与放牧效率）和相关的猎物性状变化（可食性与增长率）。纤毛虫微藻系统的实验室实验将调查间和种内的消费者性状的变化依赖于猎物组成和其他纤毛虫竞争对手的存在，以及长期的人口动态（25至40代）和相互作用的营养水平之间的反馈回路。实验数据将用于校准和验证多物种模型，这将有助于确定在关于种群动态、群落变异和维持性状变异（即功能多样性）的实验中观察到的模式的驱动机制。同时，模型模拟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实验和理论知识的性状动态在多物种食物网，并将大大提高我们的理解的后果，生物多样性丧失的营养动态和生态系统功能。

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.