Data from: Characterizing the contribution of plasticity and genetic differentiation to community-level trait responses to environmental change

The match between functional trait variation in communities and environmental gradients is maintained by three processes: phenotypic plasticity and genetic differentiation (intraspecific processes), and species turnover (interspecific). Recently, evidence has emerged suggesting that intraspecific variation might have a potentially large role in driving functional community composition and response to environmental change. However, empirical evidence quantifying the respective importance of phenotypic plasticity and genetic differentiation relative to species turnover is still lacking. We performed a reciprocal transplant experiment using a common herbaceous plant species (Oxalis montana) among low-, mid-, and high-elevation sites to first quantify the contributions of plasticity and genetic differentiation in driving intraspecific variation in three traits: height, specific leaf area and leaf area. We next compared the contributions of these intraspecific drivers of community trait-environment matching to that of species turnover, which had been previously assessed along the same elevational gradient. Plasticity was the dominant driver of intraspecific trait variation across elevation in all traits, with only a small contribution of genetic differentiation among populations. Local adaptation was not detected to a major extent along the gradient. Fitness components were greatest in O. montana plants with trait values closest to the local community-weighted means, thus supporting the common assumption that community-weighted mean trait values represent selective optima. Our results suggest that community-level trait responses to ongoing climate change should be mostly mediated by species turnover, even at the small spatial scale of our study, with an especially small contribution of evolutionary adaptation within species.群落功能性状变异与环境梯度间的匹配关系由三类过程维持：表型可塑性（phenotypic plasticity）与遗传分化（genetic differentiation，二者均为种内过程），以及物种周转（species turnover，种间过程）。近期已有研究证据表明，种内变异在驱动功能群落组成及其对环境变化的响应中，或许扮演着极为关键的角色。然而，目前仍缺乏能够量化表型可塑性、遗传分化相较于物种周转各自重要性的实证研究。本研究针对常见草本植物山酢浆草（Oxalis montana），在低、中、高海拔样地开展互易移植实验，首先量化了可塑性与遗传分化对三类功能性状——株高、比叶面积（specific leaf area）与叶面积——的种内变异的贡献程度。随后，我们将上述驱动群落性状-环境匹配的种内因子的贡献度，与此前沿同一海拔梯度评估得到的物种周转贡献度进行了对比。研究显示，在所有调研性状中，可塑性是驱动海拔梯度内种内性状变异的主导因子，种群间的遗传分化仅贡献极小的比例。沿该海拔梯度未检测到显著的本地适应现象。当山酢浆草植株的性状值与本地群落加权平均（community-weighted mean）性状值最为接近时，其适合度组分表现最优，这一结果支持了“群落加权平均性状值代表选择最优值”的通用学术假设。本研究结果表明，针对当前持续发生的气候变化，群落水平的性状响应应主要由物种周转所介导——即便在本研究的小空间尺度下亦是如此，而物种内部的进化适应的贡献度则微乎其微。