Fishes are sensitive to their thermal environment and face an uncertain future in a warming world. Theoretically, populations in novel environments might express greater levels of phenotypic variability to increase the chance of surviving—and eventually thriving—in the new conditions. Most research on the effect of the early thermal environment in fish species focuses on average phenotypic effects rather than phenotypic variability, but to understand how fishes will respond to rising temperatures we need to consider both the average response of the population, as well as the breadth of individual responses. Here we present the first meta‐analysis on the effects of developmental temperature in fishes. Using data from 43 species and over 6,000 individual fish, we show that a change in developmental temperature induces a significant change in phenotypic means and variability, but differently depending on whether the temperature is increased or decreased. Decreases in temperature (cool environments) showed a significant decrease in phenotypic means and no change in phenotypic variability. Increases in temperature (warm environments) showed a non‐significant increase in phenotypic means and a marginally significant increase in phenotypic variability. Larger increases in temperature saw greater increases in phenotypic variability, but no increase in the mean phenotypic response. Together, our results suggest that fishes exhibit both directed and stochastic developmental plasticity in response to warming temperatures, which could facilitate or accelerate adaptation to a changing environment.

中文翻译：

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发育温度影响表型均值和变异性：鱼类数据的荟萃分析

鱼类对它们的热环境很敏感，在变暖的世界中面临着不确定的未来。从理论上讲，新环境中的种群可能会表现出更高水平的表型变异性，以增加在新条件下生存并最终繁荣的机会。大多数关于早期热环境对鱼类物种影响的研究都集中在平均表型效应而不是表型变异上，但要了解鱼类对温度升高的反应，我们需要同时考虑种群的平均反应和广度个人的反应。在这里，我们提出了关于鱼类发育温度影响的首次荟萃分析。使用来自 43 个物种和超过 6,000 条鱼的数据，我们表明，发育温度的变化会引起表型均值和变异性的显着变化，但根据温度是升高还是降低而有所不同。温度的降低（凉爽的环境）表明表型均值显着降低，而表型变异性没有变化。温度升高（温暖环境）显示表型均值不显着增加，表型变异略显着增加。温度升高幅度越大，表型变异性越大，但平均表型反应没有增加。总之，我们的结果表明，鱼类在响应变暖的温度时表现出定向和随机的发育可塑性，这可以促进或加速对不断变化的环境的适应。