Data from: Latitudinal patterns of phenology and age-specific thermal performance across six Coenagrion damselfly species

Using a combination of computer simulations and laboratory experiments we test if the thermal sensitivity of growth rates change during ontogeny in damselfly larvae and if these changes can be predicted based on the natural progression of average temperature or thermal variability in the field. The laboratory experiment included replicated species from Southern, Central and Northern Europe. Although annual fluctuations in temperature represent a key characteristic of temperate environments, few studies of thermal performance have considered the ecological importance of the studied traits within a seasonal context. Instead, thermal performance is assumed to remain constant throughout ontogeny and reflect selection acting over the whole life cycle. The laboratory experiment revealed considerable variation among species in the strength and direction of ontogenetic performance shifts. In four species from Southern and Central Europe, reaction norms were steepest during early ontogeny, becoming less steep during later ontogenetic stages (indicative of low-temperature acclimation). In one Northern European species, the slope of reaction norms did not change during ontogeny. In the other North European species, reaction norms became steeper during ontogeny (indicative of high-temperature acclimation). We had expected high-latitude species to show strong low-temperature acclimation responses, because they have a short flight season and inhabit a strongly seasonal environment. Instead, we found the reversed pattern low-latitude species displayed strong low-temperature acclimation responses and high-latitude species displayed weak, or even reversed, acclimation responses to low temperatures. These findings suggest that low-temperature acclimation may be less beneficial and possibly more costly in habitats with rapid seasonal transitions in average temperature. We conclude that thermal performance traits are more dynamic than typically assumed and caut ion against using results from single ontogenetic stages to predict species' responses to changing environmental conditions.本研究结合计算机模拟与室内受控实验，探究豆娘幼虫（damselfly larvae）的生长速率热敏感性是否会随个体发育（ontogeny）发生改变，以及这类变化能否依据野外环境中平均温度或热变异性的自然时序动态进行预测。本次室内实验纳入了来自南欧、中欧与北欧的多个重复物种类群。尽管温度年际波动是温带环境的核心特征，但目前鲜有研究在季节生态背景下探讨热性能相关性状的生态学重要性；此前的研究多默认热性能在个体发育全程保持恒定，并将其视为作用于整个生命周期的选择压力的反映。室内实验结果显示，不同物种的个体发育性能变化强度与方向均存在显著差异：在来自南欧与中欧的4个物种中，其反应规范（reaction norms）在个体发育早期最为陡峭，后期则逐渐趋缓，该模式指示低温驯化（acclimation）效应；北欧的1个物种，其反应规范斜率在个体发育过程中未发生显著改变；而其余北欧物种的反应规范则随个体发育愈发陡峭，该模式指示高温驯化效应。我们原本预期高纬度物种会表现出较强的低温驯化响应——鉴于其飞行期较短且栖息于季节性极强的环境中，但实际观测结果却呈现出相反的模式：低纬度物种呈现出显著的低温驯化响应，而高纬度物种的低温驯化响应则较弱，甚至出现逆转。上述结果表明，在平均温度随季节快速转换的生境中，低温驯化的益处可能相对有限，甚至可能带来更高的演化成本。本研究结论指出，热性能相关性状的动态性远超此前的普遍认知，同时告诫研究者不应仅依据单个发育阶段的实验结果，预测物种对环境变化的响应。