Data from: Nonlinear averaging of thermal experience predicts population growth rates in a thermally variable environment

As thermal regimes change worldwide, projections of future population and species persistence often require estimates of how population growth rates depend on temperature. These projections rarely account for how temporal variation in temperature can systematically modify growth rates relative to projections based on constant temperatures. Here,we tested the hypothesis that time-averaged population growth rates in fluctuating thermal environments differ from growth rates in constant conditions as a consequence of Jensen’s inequality, and that the thermal performance curves (TPCs) describing population growth in fluctuating environments can be predicted quantitatively based on TPCs generated in constant lab conditions. With experimental populations of the green alga Tetraselmis tetrahele, we show that nonlinear averaging techniques accurately predicted increased as well as decreased population growth rates influctuating thermal regimes relative to constant thermal regimes. We extrapolate from these results to project critical temperatures for population growth and persistence of 89 phytoplankton species in naturally variable thermal environments. These results advance our ability to predict population dynamics in the context of global change.随着全球范围内热状况（thermal regimes）发生改变，预测未来种群与物种的存续情况往往需要估算种群增长率对温度的依赖关系。但这类预测极少考虑温度的时间变异会系统性地改变种群增长率，而这一效应无法通过基于恒温条件的预测得以体现。本研究验证了两项假说：其一，波动热环境下的时间平均种群增长率与恒温条件下的增长率存在差异，该差异源于延森不等式（Jensen’s inequality）；其二，描述波动环境中种群增长的热性能曲线（thermal performance curves, TPCs），可基于实验室恒温条件下获得的热性能曲线进行定量预测。本研究以绿藻四鞭四列藻（Tetraselmis tetrahele）的实验种群为材料，结果显示非线性平均技术可准确预测相较于恒温热环境，波动热环境下种群增长率的增减变化。基于上述研究结果，我们进一步外推，以预测89种浮游植物在自然可变热环境下，种群增长与存续所需的临界温度。本研究结果提升了我们在全球变化背景下预测种群动态的能力。