Data_Sheet_1_Metatranscriptome Profiling Indicates Size-Dependent Differentiation in Plastic and Conserved Community Traits and Functional Diversification in Dinoflagellate Communities.pdf

Communities of microscopic dinoflagellates are omnipresent in aquatic ecosystems. Consequently, their traits drive community processes with profound effects on global biogeochemistry. Species traits are, however, not necessarily static but respond to environmental changes in order to maintain fitness and may differ with cell size that scales physiological rates. Comprehending such trait characteristics is necessary for a mechanistic understanding of plankton community dynamics and resulting biogeochemical impacts. Here, we used information theory to analyze metatranscriptomes of micro- and nano-dinoflagellate communities in three ecosystems. Measures of gene expression variations were set as a proxy to determine conserved and plastic community traits and the environmental influence on trait changes. Using metabarcoding, we further investigated if communities with a more similar taxon composition also express more similar traits. Our results indicate that plastic community traits mainly arise from membrane vesicle associated processes in all the environments we investigated. A specific environmental influence on trait plasticity was observed to arise from nitrogen availability in both size classes. Species interactions also appeared to be responsible for trait plasticity in the smaller-sized dinoflagellates. Additionally, the smaller-sized dinoflagellate communities are characterized by the expression of a large pool of habitat specific genes despite being taxonomically more similar across the habitats, in contrast to the microplanktonic assemblages that adapted to their environments by changing species composition. Our data highlight the functional diversification on the gene level as a signature of smaller sized dinoflagellates, nitrogen availability and species interactions as drivers of trait plasticity, and traits most likely linked to fitness and community performance.

微型甲藻（microscopic dinoflagellates）群落在水生生态系统中无处不在。因此，其功能性状驱动群落过程，对全球生物地球化学循环产生深远影响。然而，物种性状并非一成不变：为维持自身适应度，它们会响应环境变化，且可能随调控生理速率的细胞大小而异。明晰这类性状特征，是从机制层面理解浮游植物群落动态及其生物地球化学影响的必要前提。本研究利用信息论方法，分析了三类水生生态系统中微型与纳米级甲藻群落的宏转录组（metatranscriptome）。我们将基因表达变异的量化指标作为替代变量，用以鉴定保守型与可塑性群落性状，以及环境对性状变化的调控作用。借助元条形码（metabarcoding）技术，本研究进一步探究了分类组成更为相似的群落，其性状表达是否也更为相近。研究结果显示，在所有调研生境中，可塑性群落性状主要源自膜囊泡相关的生理过程。我们观察到，两类大小类群的性状可塑性均受到氮素可利用性这一特定环境因子的调控。物种间相互作用同样被证实是小型甲藻群落性状可塑性的驱动因素。此外，与通过改变物种组成以适应环境的微型浮游生物集合体不同，尽管跨生境的分类学相似性更高，小型甲藻群落仍以大量生境特异性基因的表达为特征。本研究数据表明，基因层面的功能分化是小型甲藻群落的标志性特征，氮素可利用性与物种间相互作用则是性状可塑性的核心驱动因子，且相关性状极有可能与群落适应度及群落表现密切相关。