Rapid evolution of latitudinal clines in growth and defence of an invasive weed

Abstract

Summary Re‐establishment of heritable latitudinal clines in growth‐related traits has been recognised as evidence for adaptive evolution in invasive plants. However, less information is known about latitudinal clines in defence and joint clinal evolution of growth and defence in invasive plants. We planted 14 native Argentinean populations and 14 introduced Chinese populations of Alternanthera philoxeroides in replicate common gardens in China. We investigated the latitudinal clines of traits related to growth and defence, and plasticity of these traits in relation to experiment site and soil nitrogen. We found that chemical defence decreased with latitude in introduced populations but increased with latitude in native populations. For growth rate, latitudinal clines were positive in introduced populations but nonexistent in native populations. There were also parallel positive latitudinal clines in total/shoot biomass and specific leaf area. Experiment site affected the occurrence or magnitude of latitudinal clines in growth rate, branch intensity and triterpenoid saponins concentration. Introduced populations were more plastic to experiment site and soil nitrogen than native populations. We provide evidence for rapid evolution of clines in growth and defence in an invasive plant. Altered herbivory gradients and trade‐off between growth and defence may explain nonparallel clines between the native and introduced ranges.

Effects of different scenarios of temperature rise and biological control agents on interactions between two noxious invasive plants

“…Therefore, the defoliation of A. philoxeroides is high, and its performance is limited. A. philoxeroides allocates more resources to growth or reproduction and fewer resources to defence due to its release from specialist enemies at high latitudes (Yang et al, 2021). In addition, our study showed that E. crassipes restricted the population expansion of A. philoxeroides in warmer ranges where both invasive plant species co-occur.…”

Plant invasion alters latitudinal pattern of plant‐defense syndromes

“…The generality of this hypothesis has been called into question as latitudinal trends in herbivory and plant defense are highly variable in strength and direction (Moles et al 2011), and the alternative range center hypothesis posits a hump shaped relationship between latitude and herbivory or defense (Garcia et al 2000, Woods et al 2012. Nevertheless, latitudinal gradients in herbivory and defense seem to be common for native plants (Bhattarai et al 2017, Yang et al 2021.…”

“…Geographic patterns in plant-herbivore interactions may change during the spread of invasive plants as a result of altered herbivore communities and of having had insufficient time for evolution of gradients that parallel the ones in the native range (Bezemer et al 2014, Cronin et al 2015, Yang et al 2021. For example, herbivory of Phragmites australis in the field decreased with latitude among native populations, but not among introduced populations (Cronin et al 2015).…”

“…This non-parallel latitudinal gradients between native and introduced populations may result in greater herbivore pressure on native than introduced populations (i.e., enemy release) at low latitudes but no or less difference in herbivore pressure at higher latitudes (Bezemer et al 2014, Cronin et al 2015. Consequently, introduced populations may experience different evolutionary trajectories along latitude, which may confound inferences on evolutionary changes in defense phenotypes of invasive plants (Colautti et al 2009, Yang et al 2021. While there is increasing awareness of this issue, the incorporation of such large-scale heterogeneity in plant-herbivore interactions into studies of the evolution of invasive plants defenses remains an open and important task.…”

Phenotypic plasticity of <i>Alternanthera philoxeroides</i> in response to simulated daily warming in the Tibet Plateau in introduced vs. native populations

“…全球变暖和生物入侵是全球生态变化的重要 研究内容 (Sala et al, 2000)。气候变暖对物种分布、 群落组成和生态系统结构有着至关重要的影响 (Shabani et al, 2020), 也为外来植物的入侵和扩张 创造了条件 (Sorte et al, 2013)。气候变暖条件下, 随 着"热岛"的形成和物种传播方式的改变, 植物能将 分 布 范 围 扩 张 到 更 高 纬 度 和 更 高 海 拔 的 地 区 (Walther, 2002)。对于年均气温较低的生境, 气候变 暖的影响更加显著 (Harvey, 1995;Janion-Scheepers et al, 2018)。 对温度响应的可塑性是植物成功入侵的关键 因素之一 (Hyldgaard & Brix, 2012)。已有研究指出, 在气候快速变化的背景下, 表型可塑性是植物适应 短 期 温 度 波 动 和 长 期 温 度 变 化 的 决 定 性 策 略 (Nicotra et al, 2010)。表型可塑性通常被定义为个体 基因型为响应环境变异而产生不同表型的能力 (Pigliucci, 2001), 在 生 物 入 侵 中 具 有 重 要 作 用 (Richards et al, 2006)。表型可塑性增强进化假说 (evolution of increased phenotypic plasticity hypothesis) 预测, 定植到新环境的入侵植物种群相比于原产地 种群具有演化出更强表型可塑性的潜力 (Richards et al, 2006)。此前对可塑性进化的研究涵盖了外来植 物性状对水分条件、光照变化、土壤养分、邻体根 系 以 及 天 敌 防 御 等 的 响 应 (DeWalt et al, 2004;Hawkins, 2018;于良瑞等, 2020;Lucob-Agustin et al, 2021;Yang et al, 2021) (Hyldgaard & Brix, 2012), 且已有的部分研究聚焦 于热带和温带地区 (Zhou & He, 2020;黄河燕等, 2021), 较少关注入侵植物在高寒地区对增温的响 应; 且研究多聚焦于植物适合度相关性状 (He et al, 2012;Ren et al, 2020), 而植物的防御性状(特别是 次生代谢抗性产物)很少报道 (Bauerfeind & Fischer, 2013)。 喜旱莲子草(Alternanthera philoxeroides, 又称 空心莲子草、 水花生)是苋科莲子草属一种原产于阿 根廷的多年生草本植物, 能适应多种生境且生长迅 速 (Holm et al, 1969), 现已广泛分布于欧洲和非洲 以外的大陆和岛屿 (Buckingham, 1995;Sainty et al, 1997) 1 Effects of simulated daily warming on fitness traits, functional traits and defense traits between two different origins (introduced and native) of Alternanthera philoxeroides (F (P)). BI, Branching intensity; RSR, Root to shoot ratio; SLA, Specific leaf area; SSL, Specific stem length.…”