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 toward 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. Toward 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 were 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 processes 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.

在欧洲全域范围内，受随机效应与选择作用的共同影响，遗传多样性预计会随着纬度向北逐渐降低，这可能导致表型变异缩减，同时削弱种群未来适应环境变化的遗传潜力。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重要参考。在一项模拟不同冬季温度条件的实验中，我们针对源自大范围纬度梯度的天然禾本科植物高燕麦草（Arrhenatherum elatius）种群，评估了其数量性状变异、遗传多样性及遗传分化水平。总体而言，高纬地区的种群个体更小，开花概率也更低。随着纬度向北推移，种群对不同冬季温度的绝对表型可塑性响应，以及生物量生产相关性状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）数据得到的中性预期值，提示此类分化属于适应性分化。生物量生产相关性状的分化未超出中性遗传分化的范畴，但其变化模式与中性遗传分化高度吻合，表明观测到的梯度性状变异是由与迁移相关的过程所主导。本研究结果证实，高燕麦草沿纬度梯度分布的遗传多样性与性状分化格局，可能是局部选择与遗传漂变共同作用的结果。