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...欧洲全境范围内，遗传多样性（genetic diversity）整体呈现随纬度升高（向北）而降低的趋势，该现象由随机效应与选择效应（stochastic and selective effects）介导，可能导致表型变异（phenotypic variation）缩减，且未来种群适应环境变化的遗传潜力下降。明晰此类纬度梯度格局，可为育种或辅助迁移（assisted migration）策略的种源选择（provenance selection）提供理论依据。本研究通过模拟不同冬季温度的实验，对源自大范围纬度梯度的天然禾本科植物燕麦草（Arrhenatherum elatius）种群的数量性状变异（quantitative trait variation）、遗传多样性及遗传分化（genetic differentiation）进行了评估。总体而言，高纬度北部种群的个体体量更小，开花概率也更低。随着纬度向北升高，种群对不同冬季条件的绝对表型可塑性响应（plastic response），以及生物量生产（biomass production）相关性状的遗传力（heritability）均显著下降。株高与开花概率的遗传分化程度极高，且显著高于基于中性期望（neutral expectations）推导的预期水平……