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

细菌细胞大小、小菌落形成和附着在颗粒/聚集体表面的变化可被视为水生细菌抵抗原生动物放牧和环境条件变化（例如营养物和有机物的可用性）的关键特征。因此，具有低表型可塑性（非可塑性，自由或表面附着）的专家可以与具有高表型可塑性（可塑性，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）。从理论上讲，专家的变化与低表型可塑性（无论是免费或附加）导致明显的捕食者-猎物周期，而通才与高表型可塑性抑制这些振荡，从而稳定系统。模型预测，通才的青睐，在环境参数的波动，如生态系统的干扰，但他们的稳定作用导致专家的偏好。然而，在实验分析捕食者-猎物的相互作用和动力学时，细菌生活方式的这种差异并没有被考虑在内。我们的建议解决了DynaTrait的核心问题，即通过何种机制，现有的性状变异在猎物/捕食者水平的影响，在两个营养水平的动态，然后反馈的性状变异的维护。我们将结合联合收割机实验和建模企业，以检查（联合）的影响，快速进化和表型可塑性的反捕食防御捕食者-猎物动态恒化器。我们将使用2个具有窄可塑性的捕食者（一个捕食者吃自由细菌，另一个捕食者吃表面附着细菌），而不是仅使用一个具有高表型可塑性的捕食者。我们建议，通才猎物抑制捕食者-捕食者循环，从而稳定系统。稳定的环境条件下，应导致主导地位的非塑料专业猎物（小性状范围），而不断变化的环境应有利于塑料通才猎物（高性状范围）。表型塑料猎物，从而决定共存的2个不同的专业捕食者和变化的专业通才细菌的比例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联系使我们能够阐明生态和进化模式，以推广微生物之间的相互作用。在第二步中，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对生物多样性和生态系统功能的反馈程度。

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.