Institute of Wetland Ecology & Clone Ecology; Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, Taizhou University, Taizhou, China.
Institute of Environment and Ecology, Academy of Environmental Health and Ecological Security, School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China.
Ann Bot. 2021 Jan 1;127(1):123-133. doi: 10.1093/aob/mcaa150.
Clonal plants dominate many plant communities, especially in aquatic systems, and clonality appears to promote invasiveness and to affect how diversity changes in response to disturbance and resource availability. Understanding how the special physiological and morphological properties of clonal growth lead to these ecological effects depends upon studying the long-term consequences of clonal growth properties across vegetative generations, but this has rarely been done. This study aimed to show how a key clonal property, physiological integration between connected ramets within clones, affects the response of clones to disturbance and resources in an aquatic, invasive, dominant species across multiple generations.
Single, parental ramets of the floating stoloniferous plant Pistia stratiotes were grown for 3 weeks, during which they produced two or three generations of offspring; connections between new ramets were cut or left intact. Individual offspring were then used as parents in a second 3-week iteration that crossed fragmentation with previous fragmentation in the first iteration. A third iteration yielded eight treatment combinations, zero to three rounds of fragmentation at different times in the past. The experiment was run once at a high and once at a low level of nutrients.
In each iteration, fragmentation increased biomass of the parental ramet, decreased biomass of the offspring and increased number of offspring. These effects persisted and compounded from one iteration to another, though more recent fragmentation had stronger effects, and were stronger at the low than at the high nutrient level. Fragmentation did not affect net accumulation of mass by groups after one iteration but increased it after two iterations at low nutrients, and after three iterations at both nutrient levels.
Both the positive and negative effects of fragmentation on clonal performance can compound and persist over time and can be stronger when resource levels are lower. Even when fragmentation has no short-term net effect on clonal performance, it can have a longer-term effect. In some cases, fragmentation may increase total accumulation of mass by a clone. The results provide the first demonstration of how physiological integration in clonal plants can affect fitness across generations and suggest that increased disturbance may promote invasion of introduced clonal species via effects on integration, perhaps especially at lower nutrient levels.
克隆植物在许多植物群落中占据主导地位，特别是在水生系统中，而克隆性似乎促进了入侵，并影响了多样性在受到干扰和资源可利用性时的变化方式。了解克隆生长的特殊生理和形态特性如何导致这些生态效应，取决于研究克隆生长特性在多个营养代中对长期后果，但这很少被研究过。本研究旨在展示连接克隆内的分株之间的生理整合这一关键克隆特性如何影响水生入侵优势种克隆对干扰和资源的反应，研究跨越多个世代。
单独的母体分株浮萍被种植 3 周，在此期间它们产生了两代或三代后代；新分株之间的连接被切断或保持完整。然后，将单个后代用作父母，进行第二次 3 周的迭代，在第一次迭代中交叉分割与以前的分割。第三次迭代产生了 8 种处理组合，过去不同时间进行零到三轮的分割。实验在高和低营养水平下各进行了一次。
在每次迭代中，分割增加了母体分株的生物量，降低了后代的生物量，并增加了后代的数量。这些影响从一次迭代持续并累积到另一次迭代，尽管最近的分割具有更强的影响，并且在低营养水平下更强。分割在一次迭代后对群体的净质量积累没有影响，但在低营养水平下两次迭代后增加了影响，在两个营养水平下三次迭代后都增加了影响。
分割对克隆表现的积极和消极影响可以随着时间的推移而累积和持续，并且在资源水平较低时可能更强。即使分割对克隆表现没有短期的净影响，它也可能有长期的影响。在某些情况下，分割可能会增加克隆的总质量积累。研究结果首次证明了克隆植物的生理整合如何影响几代的适应性，并表明增加干扰可能通过对整合的影响促进引入的克隆物种的入侵，尤其是在较低的营养水平下。
