To better predict how populations and communities respond to climatic temperature variation, it is necessary to understand how the shape of the response of fitness‐related rates to temperature evolves (the thermal performance curve). Currently, there is disagreement about the extent to which the evolution of thermal performance curves is constrained. One school of thought has argued for the prevalence of thermodynamic constraints through enzyme kinetics, whereas another argues that adaptation can—at least partly—overcome such constraints. To shed further light on this debate, we perform a phylogenetic meta‐analysis of the thermal performance curves of growth rate of phytoplankton—a globally important functional group—controlling for environmental effects (habitat type and thermal regime). We find that thermodynamic constraints have a minor influence on the shape of the curve. In particular, we detect a very weak increase of maximum performance with the temperature at which the curve peaks, suggesting a weak “hotter‐is‐better” constraint. Also, instead of a constant thermal sensitivity of growth across species, as might be expected from strong constraints, we find that all aspects of the thermal performance curve evolve along the phylogeny. Our results suggest that phytoplankton thermal performance curves adapt to thermal environments largely in the absence of hard thermodynamic constraints.

中文翻译：

---

浮游植物热响应在没有硬热力学约束的情况下适应

为了更好地预测人口和社区如何对气候温度变化做出反应，有必要了解适应度相关速率对温度的响应形状（热性能曲线）如何演变。目前，关于热性能曲线演变的受限程度存在分歧。一个学派认为通过酶动力学普遍存在热力学约束，而另一个学派则认为适应可以——至少部分地——克服这些约束。为了进一步阐明这一争论，我们对浮游植物生长速率的热性能曲线进行了系统发育荟萃分​​析 - 一个全球重要的功能组 - 控制环境影响（栖息地类型和热状态）。我们发现热力学约束对曲线的形状影响很小。特别是，我们检测到随着曲线达到峰值的温度，最大性能的增加非常微弱，这表明“越热越好”约束很弱。此外，我们发现热性能曲线的所有方面都沿着系统发育进化，而不是像强约束所预期的那样，物种之间的生长具有恒定的热敏感性。我们的结果表明，浮游植物热性能曲线在很大程度上在没有硬热力学约束的情况下适应热环境。我们发现热性能曲线的所有方面都沿着系统发育进化，而不是像强约束所预期的那样，物种间的生长具有恒定的热敏感性。我们的结果表明，浮游植物热性能曲线在很大程度上在没有硬热力学约束的情况下适应热环境。我们发现热性能曲线的所有方面都沿着系统发育进化，而不是像强约束所预期的那样，物种间的生长具有恒定的热敏感性。我们的结果表明，浮游植物热性能曲线在很大程度上在没有硬热力学约束的情况下适应热环境。