Diversity loss and trait dynamics in natural plankton communities

该项目的目标是评估来自具有共同进化史的自然群落的特征丧失对特征动态的影响，以及它们对消费者健康和生产力的影响。在这种特征多样性及其对生产者和消费者群落动态的影响的背景下，这一总体目标可以通过湖泊食物网中浮游植物-浮游动物界面的物种特定特征(色素和脂肪酸组成)来很好地解决。我们拟议的工作方案旨在调查以下研究问题：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野外浮游生物种群相关，并在“野生自然”中显示出更复杂的动态？因此，仅凭实验室研究很难预测重要生态生理特性损失的后果，特别是在发生复杂的相互作用和反馈循环的情况下。因此，迫切需要对物种多样性中被操纵的进化的野外群落进行调查。我们将通过使用自然浮游植物群落的一系列可检验假说(A-C)来解决这一研究问题。我们将在两种不同的损失情况下(稀有物种的丧失，对压力敏感的物种的丧失)和在野外和对照的实验室实验中沿着营养梯度(从少营养到真营养)来研究这些假说。a)在“野生自然”中影响浮游生物动态的生态相关的、动态的和功能的特征是例如浮游植物的分类群特定的色素组成和浮游植物群落中必需的脂类(特别是脂肪酸)的分类群特定的组成。b)自然浮游植物(色素、脂肪酸)的分类群和功能特征的多样性与草食性浮游动物群落的营养互补有关。C)不同的浮游动物群体(例如，不同的水蚤基因类型)对必需脂肪酸的可获得性的限制的敏感性不同。因此，特征多样性(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特征产生动态反馈效应。这些假说将通过实验室和现场实验以双重方式解决。通过回答上述研究问题，我们将首次能够估计自然中上层群落特征损失的重要性，并将个体生态生理特征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.