Maternal provisioning is structured by species’ competitive neighborhoods

Differential maternal provisioning of offspring in response to environmental conditions has been argued as ‘the missing link’ in plant life histories. Although empirical evidence suggests that maternal provisioning responses to abiotic conditions are common, there is little understanding of how differences in maternal provisioning manifest in response to competition. Frequency manipulations are commonly employed in ecological studies to assess the strength of interspecific competition, relative to intraspecific competition, and we used frequency manipulations to test how competition in two soil moisture environments affects maternal provisioning of seed mass. Specifically, for 15 pairs comprised from 25 annual plant species that occur in California, we varied the relative frequencies of conspecific to heterospecific competitors from 90% (intraspecific competition) to 10% (interspecific competition). We found that conspecific frequency affected maternal provisioning (seed mass) in 12 of ...母本针对环境条件对子代进行的差异化资源供给（maternal provisioning），被认为是植物生活史研究中的‘缺失一环’。尽管已有实验证据表明，母本资源供给对非生物环境的响应较为普遍，但学界对母本资源供给的差异如何响应竞争压力仍知之甚少。频率操控实验是生态学研究中常用于评估种间竞争（interspecific competition）相较于种内竞争（intraspecific competition）强度的研究手段；本研究借助频率操控实验，探究两种土壤水分环境下的竞争如何影响母本对种子质量（seed mass）的资源供给。具体而言，本研究选取分布于加利福尼亚州的25种一年生植物构建15组配对，将同种竞争者与异种竞争者的相对频率从90%（对应种内竞争）调整至10%（对应种间竞争）。本研究发现，在12组……中，同种竞争者的频率会影响母本的资源供给（即种子质量）。