Flexible until it snaps: Dynamics of genes & traits, densities & diversity in communities challenged by environmental change

在SPP dyaTrait中需要解决的主要和关键问题之一是，多样性是否允许通过特征动态在生态群落内进行反馈，从而反过来促进多样性的维持--特别是在应对环境变化的情况下。环境条件的变化，如污染物暴露和水温上升，与未知的添加剂相互作用，对生物群产生协同或拮抗作用。社区反馈跨越了基因和特征、密度和多样性的动态，对于缓冲社区对环境变化的反应可能是至关重要的。在这里，我们关注由原生生物组成的模式群落，这些原生生物在生态系统水平上的主要功能特征不同(自养、混合营养或异养)。该项目的重点在于对环境应激源，特别是对离子银的动态反应，以及这种应激源对社区动态反应热浪等额外应激源的能力的影响。选定的形态和生理特征的变化可能不会或可能只是间接地与所看到的环境线索有关。因此，过去主要依靠形态和生理数据的方法可能会遗漏生物和生态系统反应中的一些关键方面。为了全面解决这一问题，考虑到在特定时间内可能出现的许多不同反应和反馈，采取更广泛的办法是可取的，甚至是必不可少的。因此，我们将经典的形态和生态生理学分析与基于高通量测序技术的(元)转录组分析相结合。在六个连续的工作包中，我们(I)确定目标生物对不同水平的压力源的关键反应和单个物种的动态，(Ii)确定基因和特征之间的动态和反馈，低多样性和高多样性模式群落的密度和多样性，以及(Iii)在草食动物放牧压力存在的情况下，在群落水平上确定基因和特征、密度和多样性之间的动态和反馈。该项目的综合性需要原生生物生态学、生态毒理学、生物信息学和生态系统建模方面的专业知识，这些专业知识由三个申请者和外部合作伙伴负责。简而言之，我们的假设是(1)恒定和波动的环境条件对基因表达、特征、密度和最终多样性之间的反馈具有根本不同的影响，(2)施加的压力的大小和不同应激源之间的相互作用决定了“灵活性的力量”何时崩溃。

One of the main and crucial questions to be addressed within the SPP DynaTrait is whether diversity allows feedbacks within ecological communities, through trait dynamics, that in turn promotes the maintenance of diversity - specifically in response to environmental change. Changes in environmental conditions, such as pollutant exposure and water temperature increases interact with unknown additive, synergistic or antagonistic effects on biota. Community feedbacks spanning the dynamics of genes and traits, densities and diversity are presumably of key importance for buffering the community response to, for instance, environmental changes. Here we focus on model communities consisting of protist species that differ in major functional traits that are relevant at the ecosystem level (being autotrophs, mixotrophs or heterotrophs). The focus of the project lies on the dynamic responses to environmental stressors, specifically to ionic silver, and on the effect of such stressors to constrain the communities ability to dynamically respond to additional stressors such as heat waves. Shifts in selected morphological and physiological traits may not or may only indirectly be linked to the environmental cues under view. Past approaches relying mainly on morphological and physiological data alone may therefore miss some key aspects in the organisms and ecosystems response. A much broader approach considering many different potential reactions and feedbacks at a given time would be desireable or even essential to comprehensively address this issue. We consequently combine classical morphological and ecophysiological analyses with (meta-)transcriptome analyses based on high throughput sequencing technologies. In six consecutive working packages we (i) identify key responses of the target organisms and the dynamics of single species upon varying levels of stressors, (ii) identify the dynamics and feedbacks between genes and traits, densities and diversity of low and high diversity model communities, and (iii) identify the dynamics and feedbacks between genes and traits, densities and diversity at the community level in the presence of herbivore grazing pressure. The comprehensive character of the project requires expertise in protist ecology, ecotoxicology, bioinformatics and ecosystem modeling which is covered by the three applicants and the external cooperation partner. In brief, our hypotheses are (1) that constant and fluctuating environmental conditions have fundamentally different effects on the feedback between gene expression, traits, densities and eventual diversity and (2) that the magnitude of imposed stress and the interaction between different stressors determine when "the power of flexibility" breaks down.