Data from: What drives selection on flowering time? An experimental manipulation of the inherent correlation between genotype and environment

The optimal timing of the seasonal switch from somatic growth to reproduction can depend on an individual’s condition at reproduction, the quality of the environment in which it will reproduce, or both. In annual plants, vegetative size (a function of age at flowering) affects resources available for seed production, while exposure to mutualists, antagonists, and abiotic stresses in the environment (functions of Julian date of flowering), influences success in converting resources into offspring. The inherent tight correlation between age, size, and environment obscures their independent fitness contributions. We isolated the fitness effects of these factors by experimentally manipulating the correlation between age at flowering and date of flowering in Brassica rapa. We staggered the planting dates of families with differing ages at flowering to produce experimental populations in which age at flowering and date of flowering were positively-, negatively-, or uncorrelated. In all populations, plants with an early date of flowering produced more seed than those flowering late, regardless of age or size at flowering onset. The temporal environment was thus the principal driver of selection on flowering time, but its importance relative to that of age and size varied with the presence/absence of herbivores and seed predators.生物从营养生长向繁殖转变的季节性最佳时序，既取决于个体繁殖时的生理状态，也受其繁殖所处环境质量的影响，或两者共同作用。对于一年生植物而言，营养体大小由开花年龄（age at flowering）决定，会影响种子生产可利用的资源；而植株遭遇环境中的互利共生生物、拮抗生物与非生物胁迫的情况由开花的儒略日（Julian date）决定，这会影响其将资源转化为子代的成功率。年龄、大小与环境三者之间固有的紧密相关性，掩盖了它们各自对适合度的独立贡献。本研究以芸苔（Brassica rapa）为实验材料，通过实验调控其开花年龄（age at flowering）与开花日期（date of flowering）之间的相关性，分离出上述各因素对适合度的影响效应：具体而言，我们调整不同开花年龄家系的播种日期，构建出三类实验种群，其中开花年龄（age at flowering）与开花日期（date of flowering）分别呈正相关、负相关或无相关性。在所有实验种群中，开花日期（date of flowering）较早的植株相较于开花较晚的植株，无论其开花起始时的年龄与大小如何，均能产生更多的种子。由此可见，时间环境是驱动开花时间选择的主要因素，但其相较于年龄与大小的重要性，会随植食性动物与种子捕食者的存在与否发生变化。