Planktonic ecosystems are usually modeled in terms of autotrophic and heterotrophic compartments. However, the trophic strategy of unicellular organisms can take a range of mixotrophic strategies with both autotrophic and heterotrophic contributions. The dominant emerging strategy found in nature depends on the environment (both biotic and abiotic aspects) and the cell size and influences key ecosystem functions like trophic transfer and carbon export. Ecosystem models that faithfully represent this diversity of trophic strategies are lacking. Here we develop a trait‐based model of unicellular plankton with cell size as the master trait and three other traits that determine trophic strategies: investments in photosynthesis, nutrient uptake, and phagotrophy. This unicellular model spans the entire auto‐ mixo‐ hererotrophic strategy continuum and the entire size range of unicellular organisms. The model reproduces observed latitudinal patterns in biomass, primary productivity, vertical carbon export, and energy transfer efficiency; all increase with increasing latitude. The size range of mixotrophic cells is independent of the season at low latitudes. At high latitudes, the dominance of pure phototrophs during early spring restricts mixotrophic behavior to a narrower range of cell sizes and with the occurrence of relatively smaller mixotrophs during summer. The model's ability to adapt to different environmental conditions, combined with its simple conceptual structure and low number of parameters and state variables (10), makes it ideally suited for global simulation studies under changing environmental conditions.

中文翻译：

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浮游生物性状的纬度变化与生态系统功能

浮游生物生态系统通常根据自养和异养间隔进行建模。但是，单细胞生物的营养策略可以采取多种混合营养策略，同时具有自养和异养作用。在自然界发现的主要新兴策略取决于环境（生物和非生物方面）和细胞大小，并影响营养传递和碳输出等关键生态系统功能。缺乏忠实地代表这种营养策略多样性的生态系统模型。在这里，我们开发了一种基于特征的单细胞浮游生物模型，其中以细胞大小为主要特征，另外三个特征决定了营养策略：光合作用，养分吸收和吞噬能力的投资。这个单细胞模型涵盖了整个自体异养策略的连续体和单细胞生物的整个大小范围。该模型再现了生物量，初级生产力，垂直碳输出和能量转移效率中的经纬度模式。随着纬度的增加，所有这些都增加了。在低纬度地区，混合营养细胞的大小范围与季节无关。在高纬度地区，早春纯营养养分的优势将混养养分的行为限制在较窄的细胞大小范围内，并且在夏季出现了相对较小的混养养分。该模型具有适应不同环境条件的能力，并具有简单的概念结构以及少量参数和状态变量（10），