Data from: Metabolic theory and the temperature size rule explain the temperature dependence of population carrying capacity

The temperature dependence of highly conserved subcellular metabolic systems affects ecological patterns and processes across scales, from organisms to ecosystems. Population density at carrying capacity plays an important role in evolutionary processes, biodiversity and ecosystem function, yet how it varies with temperature dependent metabolism remains unclear. Though the exponential effect of temperature on intrinsic population growth rate, r, is well known, we still lack clear evidence that population density at carrying capacity, K, declines with increasing per-capita metabolic rate, as is often assumed in the metabolic theory of ecology (MTE). We experimentally tested whether temperature effects on photosynthesis propagate directly to population carrying capacity in a model species, the mobile phytoplankton Tetraselmis tetrahele. After maintaining populations at constant resource supply and temperatures (6 levels) for 43 days, we found that density declined with increasing temperature in a manner quantitatively consistent with predictions when models included temperature-dependent metabolic rates and temperature-associated body size shifts. Our results demonstrate that warming reduces carrying capacity, and that temperature effects on body size and metabolic rate interact to determine how temperature affects population dynamics. These findings bolster efforts to relate metabolic temperature dependence to population and ecosystem patterns via MTE.

高度保守的亚细胞代谢系统的温度依赖性，会影响从生物体到生态系统各尺度的生态格局与生态过程。环境容纳量（carrying capacity, K）下的种群密度在进化过程、生物多样性及生态系统功能中发挥着关键作用，然而其如何随温度依赖性代谢发生变化仍不明确。尽管温度对内禀种群增长率（intrinsic population growth rate, r）的指数效应已被广泛认知，但我们仍缺乏明确证据表明，环境容纳量下的种群密度会随个体代谢率升高而降低——这正是代谢生态学理论（Metabolic Theory of Ecology, MTE）中通常所假设的结论。我们以模式生物——移动性浮游植物四列藻（Tetraselmis tetrahele）为研究对象，通过实验检验了温度对光合作用的影响是否会直接传递至种群环境容纳量。在将种群维持在恒定资源供给与6个温度梯度下培养43天后，我们发现：当模型纳入温度依赖性代谢率以及温度相关的体型变化时，种群密度随温度升高而下降的趋势与理论预测在定量上高度一致。本研究结果证实，气候变暖会降低种群环境容纳量，且温度对体型与代谢率的影响存在交互作用，共同决定了温度调控种群动态的方式。这些发现为通过代谢生态学理论（MTE）建立代谢温度依赖性与种群及生态系统格局之间的关联提供了有力支撑。