Trait-based ecology allows much of the complexity of ecosystems to be projected onto a low-dimensional trait space. We conjecture that three key traits capture the main aspects of diversity of unicellular planktonic organisms: cell size, trophic strategies (relative investment in photosynthesis and phagotrophy) and vacuolation. The three selected traits are representative of two groups: mixotrophic protists, which in addition to phototrophy, use phagotrophic grazing as a food source, and diatoms that use fluid-filled vacuoles to increase their physical size relative to carbon biomass. We construct a trait-based model related to the three traits and determine the optimal trait values of cells of a given carbon size in a given environment. We also perform fully dynamic simulations to study the self-assembled trait distribution at steady state and throughout a seasonal cycle. Diatoms’ strategy is shown to be advantageous among small cells and under early spring conditions, in which highly vacuolated diatoms are simulated, while mixotrophy is dominant among larger cells when nutrients are limiting (summer conditions). The novelty of this approach lies in the mechanistic understanding of plankton physiology that is successfully used to capture how community trait structure emerges from trade-offs that constrain the different strategy among unicellular plankton.

中文翻译：

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空泡和混合营养单细胞浮游生物之间的竞争

基于特征的生态系统允许将生态系统的许多复杂性投影到低维特征空间上。我们推测三个主要特征捕获了单细胞浮游生物多样性的主要方面：细胞大小，营养策略（在光合作用和吞噬营养上的相对投资）和空泡化。所选的三个特征代表两组：混合营养的原生生物，除了光营养性外，还使用吞噬营养的草食作为食物来源；硅藻使用充满液体的液泡来增加其相对于碳生物量的物理尺寸。我们构建与三个特征相关的基于特征的模型，并确定在给定环境中给定碳尺寸的细胞的最佳特征值。我们还执行全动态模拟，以研究稳态和整个季节周期中自组装特征分布。硅藻的策略在小细胞中和早春条件下被证明是有利的，在早春条件下模拟了高度空泡的硅藻，而当营养物质受限时（夏季条件），混合营养在较大细胞中占主导。这种方法的新颖之处在于对浮游生物生理学的机械理解，该机制成功地用于捕获群落特征结构如何从权衡取舍而出现，这些取舍限制了单细胞浮游生物之间的不同策略。当营养受到限制时（夏季条件），混合营养在较大细胞中占主导地位。这种方法的新颖性在于对浮游生物生理学的机械理解，该机制成功地用于捕获社区特征结构如何从权衡取舍中出现，这些取舍限制了单细胞浮游生物之间的不同策略。当营养受到限制时（夏季条件），混合营养在较大细胞中占主导地位。这种方法的新颖性在于对浮游生物生理学的机械理解，该机制成功地用于捕获社区特征结构如何从权衡取舍中出现，这些取舍限制了单细胞浮游生物之间的不同策略。