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，许多生态学研究都探讨了生物多样性丧失对生态系统功能的影响，最近也是在多营养的背景下。消费者多样性对食物网动态的影响高度依赖于背景，并由食物网结构决定，涉及特定物种的特征，如消费者专门化和放牧率。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起着关键作用。拟议的项目旨在以实验室实验和基于过程的模型相结合的联合方法，评估在两个相互作用的营养水平上的特征变化的作用，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。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特定特征和权衡，例如消费者的专业化(通才和专家)、放牧和增长率(权衡：专业化和放牧效率)以及相关的猎物特征变化(可食性和增长率)。纤毛虫微藻系统的实验室实验将研究物种间和种内消费者特征的变化，依赖于猎物组成和其他纤毛虫竞争对手的存在，以及长期的种群动态(25-40代)和相互作用的营养水平之间的反馈循环。实验数据将被用来校准和验证多物种模型，该模型将有助于确定在关于种群动态、群落变异性和维持特征变异(即功能多样性)的实验中驱动观察到的模式的机制。同时，将利用模型模拟来优化后续实验的实验设计。这种联合方法将扩大现有的关于多物种食物网中特征动力学的实验和理论知识，并将大大增强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.