Comparing phenotypic plasticity in bacterial prey traits and ecological consequences by using specialist vs. generalist strains and organic aggregates as model systems

通过使用专业菌株和通才菌株和有机聚集体作为模型系统，比较细菌猎物特征的表型可塑性和生态后果

• 批准号: 257346203
• 负责人: Professor Dr. Hans-Peter Grossart
• 金额: --
• 依托单位: Abteilung 3: Plankton- und mikrobielle Ökologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/257346203?language=en
• 关键词: Comparing; phenotypic; plasticity; bacterial; prey

Changes in bacterial cell size, microcolony formation and attachment to particle/aggregate surfaces can be regarded as key traits of aquatic bacteria to counteract protozoan grazing and changes in environmental conditions, e.g. the availability of nutrients and organic matter. Thereby, specialist with a low phenotypic plasticity (non-plastic, either free or surface attached) can be distinguished from generalists with a high phenotypic plasticity (plastic, switching between free and surface-attached life stages). Trait plasticity can be induced (phenotypic plasticity; generalists) or inherited (rapid evolution; specialists). Theoretically changes of specialists with a low phenotypic plasticity (either free or attached) lead to pronounced predator-prey cycles, whereas generalists with a high phenotypic plasticity dampens these oscillations and hence stabilize the system. Models predict that generalists are favored by fluctuations in environmental parameters, e.g. ecosystem disturbances, but that their stabilizing effect leads to a preference of specialists. Yet, such differences in bacterial lifestyle have not been taken into account when experimentally analyzing predator-prey interactions and dynamics. Our proposal addresses the core question of DynaTrait, i.e. by which mechanisms the existing trait variation at the prey/predator levels influences the dynamics at both trophic levels, which then feeds back on the maintenance of trait variation. We will combine experimental and modelling enterprises to examine the (combined) effects of rapid evolution and phenotypic plasticity of antipredatory defense on predator-prey dynamics in chemostats. Instead of using only one predator with high phenotypic plasticity, we will use 2 predators with a narrow plasticity (a predator grazing free bacteria and a second predator feeding on surface-attached bacteria).Our work focus on the different bacterial lifestyles and hence physiological traits of specialist and generalist prey bacteria. We propose that generalist prey dampens predator prey cycles and thus stabilize the system. Stable environmental conditions should lead to dominance of non-plastic specialist prey (small trait range), whereas changing environments should favor plastic generalist prey (high trait range). Phenotypically plastic prey thus determines coexistence of 2 different specialist predators and changes in specialist to generalist bacteria ratio affect organic matter cycling efficiency and ecosystem functioning. The tight inter-linkage of chemostat experiments and modeling enterprises allows us to elucidating ecological and evolutionary patterns for generalization of interactions between microorganisms. In a second step we aim to link these patterns to organic matter cycling in the system. Thus we will use the trait based approach to better define to which extent phenotypic plasticity on the microorganism level feeds back to biodiversity and ecosystem function.

细菌细胞大小、微菌落形成和颗粒/聚集体表面附着的变化可以被视为水生细菌抵抗原生动物放牧和环境条件变化的关键特征，例如，养分和有机物的可用性。因此，具有低表型可塑性（非塑料，游离或表面附着）的专家可以与具有高表型可塑性（塑料，在自由和表面附着生命阶段之间切换）的通才区分开来。性状可塑性可以是诱导的（表型可塑性；通才）或遗传的（快速进化；专家）。理论上，具有低表型可塑性（无论是游离的还是附着的）的专家的变化会导致明显的捕食者-被捕食者循环，​​而具有高表型可塑性的通才会抑制这些振荡，从而稳定系统。模型预测通才会受到环境参数波动的青睐，例如。生态系统扰动，但其稳定作用引起了专家的偏好。然而，在实验分析捕食者与猎物之间的相互作用和动力学时，细菌生活方式的这种差异并未被考虑在内。我们的建议解决了 DynaTrait 的核心问题，即猎物/捕食者水平上现有的性状变异通过何种机制影响两个营养水平的动态，然后反馈到性状变异的维持。我们将结合实验和建模企业来研究快速进化和反捕食防御的表型可塑性对恒化器中捕食者-猎物动力学的（综合）影响。我们不会只使用一种具有高表型可塑性的捕食者，而是使用两种具有窄可塑性的捕食者（一种捕食者吃游离细菌，另一种捕食者以表面附着的细菌为食）。我们的工作重点是不同的细菌生活方式，以及专业和通才猎物细菌的生理特征。我们认为，通才捕食会抑制捕食者的捕食周期，从而稳定系统。稳定的环境条件应导致非塑料专业猎物（小特征范围）占主导地位，而变化的环境应有利于塑料通才猎物（高特征范围）。因此，表型塑料猎物决定了两种不同的专业捕食者的共存，而专业细菌与通用细菌比例的变化会影响有机物循环效率和生态系统功能。恒化器实验和建模企业的紧密相互联系使我们能够阐明微生物之间相互作用的生态和进化模式。第二步，我们的目标是将这些模式与系统中的有机物循环联系起来。因此，我们将使用基于性状的方法来更好地定义微生物水平上的表型可塑性在多大程度上反馈到生物多样性和生态系统功能。