Am Nat. 2018 Dec;192(6):687-697. doi: 10.1086/700114. Epub 2018 Oct 22.
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 predicted by 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 a fixed resource supply and fixed temperatures for 43 days, we found that carrying capacity declined with increasing temperature. This decline was predicted quantitatively 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.
高度保守的细胞内代谢系统的温度依赖性影响着从生物体到生态系统等多个尺度上的生态格局和过程。在进化过程、生物多样性和生态系统功能中，承载能力下的种群密度起着重要作用，但它如何随依赖于温度的代谢而变化尚不清楚。尽管温度对内在种群增长率 r 的指数效应是众所周知的，但我们仍然缺乏明确的证据表明，承载能力下的种群密度 K 会随着人均代谢率的增加而下降，这是生态代谢理论（MTE）所预测的。我们通过对一种移动性浮游植物 Tetraselmis tetrahele 的模型物种进行实验测试，来验证光合作用对种群承载能力的温度影响是否直接传递。在 43 天的时间里，我们将种群维持在固定的资源供应和固定温度下，结果发现承载能力随温度升高而下降。当模型包括温度依赖的代谢率和与温度相关的体型变化时，这种下降可以被定量预测。我们的研究结果表明，变暖会降低承载能力，并且体型和代谢率对温度的影响会相互作用，从而影响温度对种群动态的影响。这些发现为通过 MTE 将代谢的温度依赖性与种群和生态系统模式联系起来的努力提供了支持。
