Diversity loss and trait dynamics in natural plankton communities

该项目的目标是评估具有共同进化历史的自然群落中性状的丧失对性状动态的影响及其对消费者适应性和生产力的影响。在性状多样性及其对生产者和消费者群落动态的影响的背景下，通过湖泊食物网中浮游植物-浮游动物界面的物种特异性性状（色素和脂肪酸组成）可以很好地解决这一总体目标。我们提出的工作计划旨在调查以下研究问题：在实验室浮游生物群落中负责生物多样性-生态系统功能的特征是否也与自然浮游生物种群相关，并在“野生自然”中显示这些特征更复杂的动态？重要的生态生理性状丧失的后果，不能轻易地从实验室研究预测，特别是，如果复杂的相互作用和反馈回路发生。因此，迫切需要调查在物种多样性操纵下进化的野外群落。我们将利用天然浮游植物群落，用一系列可测试的假设（a - c）来解决这个研究问题。我们将在两种不同的损失情景下（稀有物种的损失，胁迫敏感物种的损失）以及沿着营养梯度（贫营养到富营养）在野外和受控实验室实验中研究这些假设。A)影响“野生自然”中浮游生物动态的生态相关、动态和功能特征，例如浮游植物的特定分类群色素组成和浮游植物群落中必需脂类（特别是脂肪酸）的特定分类群组成。B)天然浮游植物（色素、脂肪酸）的分类群及其功能性状多样性与该群落对食草浮游动物的营养互补性相关。C)不同的浮游动物类群（如不同的水蚤基因型）对必需脂肪酸可用性限制的敏感性不同。因此，性状多样性（脂肪酸）的丧失会影响浮游动物之间的竞争性相互作用。这反过来又会影响浮游动物群落的遗传和/或分类组成，从而对浮游植物群落组成和相应的功能性状产生动态反馈效应。这些假设将采用实验室和现场实验的双重方法来解决。通过回答上述研究问题，我们将能够首次估计自然远洋群落性状损失的重要性，并将个体生态生理性状的动态与生态系统功能机械地联系起来。

The project's objective is to assess the impact of a loss of traits from natural communities with shared evolutionary history on trait dynamics and their effect on consumer fitness and productivity. In such a context of trait diversity and their impact on producer and consumer community dynamics, this general objective can be particularly well addressed through species specific traits (pigment and fatty acid composition) at the phytoplankton-zooplankton interface in lake food webs. Our proposed work programme aims to investigate the following research question: Are traits that are responsible for biodiversity - ecosystem functions in laboratory plankton communities also relevant for natural field populations of plankton and show these traits more complex dynamics in "wild nature"? Consequences of losses of important ecophysiological traits can then not easily be predicted from laboratory studies alone, in particular, if complex interactions and feed-back loops occur. Investigations of evolved field communities manipulated in species diversity are therefore urgently needed. We will address this research question with a chain of testable hypotheses (A-C) using natural phytoplankton communities. We will investigate these hypotheses at two different loss scenarios (loss of rare species, loss of stress sensitive species) and along a trophic gradient (oligotroph to eutroph) in the field and in controlled laboratory experiments.A) Ecologically relevant, dynamic and functional traits affecting plankton dynamics in "wild nature" are e.g. the taxon specific pigment composition of phytoplankton and the taxon-specific composition of essential lipids (in particular fatty acids) in the phytoplankton community.B) The taxon and thereby functional trait diversity of natural phytoplankton (pigments, fatty acids) is correlated with the nutritional complementarity of this community for herbivorous zooplankton. C) Different zooplankton groups (e.g. different Daphnia genotypes) differ in their susceptibility to limitations by the availability of essential fatty acids. A loss of trait diversity (fatty acids) can thus affect competitive interactions between zooplankton. This can in turn affect the genetic and/or taxonomic composition of the zooplankton community resulting on dynamic feedback effects on phytoplankton community composition and the corresponding functional traits. These hypotheses will be addressed in a dual approach, using laboratory and field experiments. By answering the above stated research questions, we will be able for the first time to estimate the importance of trait losses in natural pelagic communities and to link mechanistically the dynamics of individual ecophysiological traits to ecosystem functioning.