Research Unit of Biodiversity, Oviedo University, 33600 Mieres, Spain;
Department of Ecology, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden.
Proc Natl Acad Sci U S A. 2020 Dec 8;117(49):31249-31258. doi: 10.1073/pnas.2002713117. Epub 2020 Nov 23.
For species to stay temporally tuned to their environment, they use cues such as the accumulation of degree-days. The relationships between the timing of a phenological event in a population and its environmental cue can be described by a population-level reaction norm. Variation in reaction norms along environmental gradients may either intensify the environmental effects on timing (cogradient variation) or attenuate the effects (countergradient variation). To resolve spatial and seasonal variation in species' response, we use a unique dataset of 91 taxa and 178 phenological events observed across a network of 472 monitoring sites, spread across the nations of the former Soviet Union. We show that compared to local rates of advancement of phenological events with the advancement of temperature-related cues (i.e., variation within site over years), spatial variation in reaction norms tend to accentuate responses in spring (cogradient variation) and attenuate them in autumn (countergradient variation). As a result, among-population variation in the timing of events is greater in spring and less in autumn than if all populations followed the same reaction norm regardless of location. Despite such signs of local adaptation, overall phenotypic plasticity was not sufficient for phenological events to keep exact pace with their cues-the earlier the year, the more did the timing of the phenological event lag behind the timing of the cue. Overall, these patterns suggest that differences in the spatial versus temporal reaction norms will affect species' response to climate change in opposite ways in spring and autumn.
为了使物种在时间上与环境保持协调，它们会利用积累度日数等线索。种群中物候事件的时间与其环境线索之间的关系可以用种群水平的反应规范来描述。环境梯度上反应规范的变化可能会加剧（共梯度变化）或减弱（反梯度变化）环境对时间的影响。为了解决物种响应的空间和季节性变化，我们使用了一个独特的数据集，该数据集包含了 91 个分类群和 178 个物候事件，这些事件是在跨越前苏联国家的 472 个监测站点网络中观察到的。我们表明，与随着与温度相关线索的推进而导致的物候事件的本地推进速度（即，多年来站点内的变化）相比，反应规范的空间变化往往会强调春季的响应（共梯度变化），并在秋季减弱（反梯度变化）。因此，与所有种群无论位置如何都遵循相同的反应规范相比，种群之间事件时间的变化在春季更大，在秋季更小。尽管存在这种局部适应的迹象，但整体表型可塑性不足以使物候事件与线索保持完全同步——年份越早，物候事件的时间与线索的时间差距就越大。总的来说，这些模式表明，空间与时间反应规范的差异将以相反的方式影响物种在春季和秋季对气候变化的响应。
