Table_1_Past Competition Affects Offspring Foliar Terpenoid Concentrations, Seed Traits, and Fitness in the Invasive Forb Erodium cicutarium (Geraniaceae).DOCX

(1) Environmental conditions experienced in the past may lead to intraspecific differences in ecological and chemical traits of plants, which likely affect future responses to altered or new environments. Whether competition by neighbors is such a trait-shaping factor is not yet well-known. We aimed to understand how the level of ancestral plant competition affects traits related to plant fitness and resource allocation, reproduction, and (phyto-)toxin accumulation in offspring, and whether a potential differentiation in these traits can be found in different geographic origins of which one belongs to the native and one to the invaded range. (2) We compared differentiation of the following traits in offspring plants of multiple populations in Erodium cicutarium (Geraniaceae): biomass, seed production, seed traits related to dispersal and germination, and concentrations of foliar mono- and sesquiterpenes. We tested the allelopatic potential of aqueous extracts of the same E. cicutarium plants on seeds of five different plant families. (3) In plants originating from populations that experienced high levels of competition, we found twice as high monoterpene concentrations. These plants also produced more biomass and a higher proportion of ripe to unripe seeds until harvesting. Seeds originating from high competition sites were shorter. Aqueous E. cicutarium leaf extracts with high terpenoid content reduced radicle length of Zea mays and radicle and hypocotyl length of E. cicutarium seedlings. (4) The results of this study provide first evidence that the surrounding vegetation may shape chemo-ecological plant traits that may be fundamental for competitive ability. Our study calls for more research testing whether competition experienced in the native range may lead to an enhanced capability of plants to establish populations and spread in a new range.

(1) 过往经历的环境条件可能引发植物生态与化学性状的种内差异，此类差异或会影响植物未来对变化环境或新生境的响应。目前学界尚未明确邻株竞争是否属于这类性状塑造因子。本研究旨在阐明祖先植株所经历的竞争强度，如何影响子代植株的适合度、资源分配、繁殖以及（植物）毒素积累相关性状，同时探究这类性状的潜在分化是否存在于不同地理起源的种群中——其中一类种群源自原生分布区，另一类则来自入侵分布区。
(2) 本研究比较了芹叶牻牛儿苗（Erodium cicutarium，牻牛儿苗科）多个种群的子代植株的以下性状分化：生物量、种子产量、与扩散和萌发相关的种子性状，以及叶片单萜与倍半萜的含量。我们利用同一芹叶牻牛儿苗植株的水提物，针对5个不同植物科的种子开展了化感潜力测试。
(3) 相较于源自低竞争生境种群的植株，源自高竞争生境种群的植株单萜浓度提升了一倍。此类植株同时具有更高的生物量，且收获时成熟种子与未成熟种子的比例更高。而源自高竞争生境的种子，其长度更短。此外，萜类化合物含量较高的芹叶牻牛儿苗叶片水提物，会抑制玉米（Zea mays）幼苗的胚根长度，以及芹叶牻牛儿苗自身幼苗的胚根与下胚轴长度。
(4) 本研究结果首次证实，周边植被可塑造植物的化学生态性状，而这类性状或对竞争能力至关重要。本研究呼吁开展更多相关研究，以验证原生分布区经历的竞争是否会提升植物在新分布区建立种群并实现扩散的能力。