Data from: Trait variation in response to varying winter temperatures, diversity patterns and signatures of selection along the latitudinal distribution of the widespread grassland plant Arrhenatherum elatius

Across Europe, genetic diversity can be expected to decline towards the North because of stochastic and selective effects which may imply diminished phenotypic variation and less potential for future genetic adaptations to environmental change. Understanding such latitudinal patterns can aid provenance selection for breeding or assisted migration approaches. In an experiment simulating different winter temperatures we assessed quantitative trait variation, genetic diversity and differentiation for natural populations of the grass Arrhenatherum elatius originating from a large latitudinal gradient. In general, populations from the North grew smaller and had a lower flowering probability. Towards the North, the absolute plastic response to the different winter conditions as well as heritability for biomass production significantly declined. Genetic differentiation in plant height and probability of flowering was very strong and significantly higher than under neutral expectations derived from SNP data, suggesting adaptive differentiation. Differentiation in biomass production did not exceed but mirrored patterns for neutral genetic differentiation, suggesting that migration related processed caused the observed clinal trait variation. Our results demonstrate that genetic diversity and trait differentiation patterns for A. elatius along a latitudinal gradient are likely shaped by both local selection and genetic drift.在欧洲全境，受随机效应与选择效应的影响，遗传多样性整体呈现随纬度升高而降低的趋势，这可能意味着表型变异的缩减，以及未来应对环境变化的遗传适应潜力下降。明晰此类纬度梯度格局，可为育种或辅助迁移策略的种源选择提供参考依据。本研究开展模拟不同冬季温度的实验，对源自大跨度纬度梯度的野生禾本科植物高燕麦草（Arrhenatherum elatius）的自然种群，评估其数量性状变异、遗传多样性与遗传分化水平。整体而言，高纬度北部的种群个体体型更小，开花概率更低。随纬度升高至北部区域，种群对不同冬季条件的绝对表型可塑性响应，以及生物量生产的遗传力均显著下降。植株高度与开花概率的遗传分化程度极高，且显著高于基于单核苷酸多态性（Single Nucleotide Polymorphism, SNP）数据得到的中性预期值，表明此类分化属于适应性分化。生物量生产的遗传分化未超出中性遗传分化的范围，但二者变化模式高度一致，表明观测到的性状梯度变异由与迁移相关的过程所驱动。本研究结果表明，高燕麦草（Arrhenatherum elatius）沿纬度梯度分布的遗传多样性与性状分化格局，大概率由本地选择与遗传漂变共同塑造。