Data from: Covariation in abscission force and terminal velocity of wind-borne sibling seeds alters long distance dispersal projections

1. Despite the fact that seeds are unlikely to be identical—even among siblings within a maternal individual—dispersal models typically use one mean trait value to represent the ability of an entire species to disperse. Previous work has shown that the environmental conditions under which individuals leave the maternal site strongly affect how far seeds will travel. However, less is known about how trait variation within individuals contributes to dispersal or how such variation might interact with abiotic factors. 2. Here, we develop the use of an ergometer in a novel application to investigate variation in seed traits, specifically the force required for seed abscission and seed terminal velocity, exhibited by seeds from different locations within maternal capitula of the invasive species Carduus nutans (Asteraceae). 3. We find that seeds from the center of capitula are significantly easier to liberate and have slower falling velocities than siblings found near the edge of capitula. When abscission force is positively correlated with terminal velocity, slowly falling, easily abscised seeds are projected to travel much further than the average seed on slow winds. 4. Our experimental and theoretical results, which together show that within-individual variation can strongly affect model projections of species dispersal, have important implications for our broader understanding of population spread rates, the spatial structure of populations, metapopulation connectivity, and gene flow in the landscape.1. 尽管即便同一母株个体所结的同胞种子之间也未必完全一致，但现有种子扩散模型通常仅以单一平均性状值来表征整个物种的扩散能力。已有研究显示，植株脱离母株原生位点时的环境条件，会显著影响种子的传播距离。然而，学界对于个体内部的性状变异如何影响种子扩散，以及这类变异如何与非生物因子产生互作，仍所知甚少。 2. 本研究将测力计（ergometer）的应用拓展至全新场景，用以探究入侵物种垂花蓟（Carduus nutans，菊科Asteraceae）母株头状花序内不同位置所结种子的性状变异，具体包括种子脱落（seed abscission）所需作用力以及种子终端降落速度（terminal velocity）两项指标。 3. 研究结果显示，头状花序中心的种子相较于边缘的同胞种子，脱落难度更低且终端降落速度更慢。当脱落力与终端降落速度呈正相关时，在低速风力条件下，易脱落且降落速度缓慢的种子的理论传播距离将显著高于平均水平的种子。 4. 本研究的实验与理论结果共同表明，个体内部的性状变异可对物种扩散的模型预测结果产生显著影响，这一发现对于我们深入理解种群扩散速率、种群空间结构、集合种群（metapopulation）连通性以及景观中的基因流均具有重要意义。