J Plant Ecol ›› 2022, Vol. 15 ›› Issue (5): 1065-1079 .DOI: 10.1093/jpe/rtac054

• Research Articles • Previous Articles     Next Articles

The importance of ecotype diversity on duckweed growth with and without salt stress

Sofa J. van Moorsel*   

  1. Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland

    *Corresponding author. E-mail: sofa.vanmoorsel@ieu.uzh.ch
  • Received:2021-10-05 Revised:2022-11-20 Accepted:2022-03-26 Online:2022-04-07 Published:2022-09-01

Abstract:

The pollution of freshwater ecosystems is threatening freshwater plant species diversity worldwide. Freshwater plants, such as the common duckweed (Lemna minor), are potentially sensitive to novel stressful environments. To test if ecotype diversity could increase resistance to stressful environments, I used seven L. minor populations and measured their growth rates with and without moderate salt stress across an ecotype diversity gradient. The L. minor populations were grown over 5 months in 92 experimental mesocosms, either in ecotype monocultures or in polyculture with either one or three conspecific ecotypes (23 unique compositions). After growing the duckweed in unperturbed conditions (phase 1), the cultures were subjected to moderate salt stress (50 mmol/L NaCl) for several weeks (phase 2). The experiment was conducted in the presence of the natural epimicrobial community associated with the different ecotypes. In phase 2, a subset of these algae added an unintentional second stressor to the experiment. The ecotypes differed in their growth rates, the fastest growing at twice the rate of others. The diversity context further shaped the ecotype growth rates. Ecotype polycultures showed higher abundances towards the end of the experiment, thus over time, as the environment deteriorated, ecotype diversity gained in importance. These findings show that within-species variation in growth rates can translate to a positive effect of ecotype diversity on population abundance. Exposure of L. minor to moderate salt levels did not significantly impact growth rates, although the effect may have been masked by reduced algal stress in the saline environments.

Key words: aquatic plant, diversity experiment, glasshouse experiment, growth rate, intraspecific diversity, Lemna minor

摘要:
生态型多样性对存在盐分胁迫和不存在盐分胁迫下浮萍生长的重要性
淡水生态系统受到的污染正在威胁着全世界淡水植物物种的多样性。浮萍(Lemna minor)等淡水植物对新出现的逆境条件具有潜在的敏感性。为了测试生态型的多样性是否可以增强这类植物对逆境的抗性,本研究使用了7个浮萍种群,并沿着一个生态型多样性梯度对存在和不存在中度盐分胁迫时的种群生长速率进行了测量。这些浮萍种群在92个实验围隔中生长了5个月,其中有生态型单一栽培,也有在5或3个同种生态型(23种独特组合)中混合栽培。在无扰条件下生长一段时间(阶段1)后,这些浮萍栽培物将被置于中等盐分胁迫(50 mmol/L NaCl)条件下数周时间(阶段2)。实验进行时存在着与不同生态型伴生的天然表观微生物群落(epimicrobial community)。在阶段2中,这些藻类的一部分受到了随机二次胁迫。这些生态型表现出了不同的生长速率,其中最快的生长速率是其它生态型的两倍。多样性的环境进一步影响了生态型的生长速率,生态型混合栽培的植株在实验结束时具有更高的丰度,因此,随着时间的推移,环境逐渐恶化,生态型的多样性也将变得更为重要。上述研究结果表明,种内生长速率的差异体现了生态型多样性对种群丰度的正向影响。在中等盐度水平下的暴露并未显著影响浮萍的生长速率,尽管这种效应可能被盐性环境中更小的藻类压力所掩盖。

关键词: 水生植物, 多样性实验, 温室实验, 生长速率, 种内多样性, 浮萍(Lemna minor)