Physical Chemistry of Nanomaterials, Institute of Chemistry and Center for Interdisciplinary Nanostructure Science and Technology, University of Kassel, 34109 Kassel, Germany.
Microbiology, Institute of Biology and Center for Interdisciplinary Nanostructure Science and Technology, University of Kassel, 34109 Kassel, Germany.
J R Soc Interface. 2021 Jun;18(179):20210146. doi: 10.1098/rsif.2021.0146. Epub 2021 Jun 16.
The unique life cycle of diatoms with continuous decreasing and restoration of the cell size leads to periodic fluctuations in cell size distribution and has been regarded as a multi-annual clock. To understand the long-term behaviour of a population analytically, generic mathematical models are investigated algebraically and numerically for their capability to describe periodic oscillations. Whereas the generally accepted simple concepts for the proliferation dynamics do not sustain oscillating behaviour owing to broadening of the size distribution, simulations show that a proposed limited lifetime of a newly synthesized cell wall slows down the relaxation towards a time-invariant equilibrium state to the order of a hundred thousand generations. In combination with seasonal perturbation events, the proliferation scheme with limited lifetime is able to explain long-lasting rhythms that are characteristic for diatom population dynamics. The life cycle thus resembles a pendulum clock that has to be wound up from time to time by seasonal perturbations rather than an oscillator represented by a limit cycle.
硅藻独特的生命周期伴随着细胞大小的持续减小和恢复，导致细胞大小分布的周期性波动，被认为是一种多年时钟。为了从分析上理解种群的长期行为，对通用的数学模型进行了代数和数值研究，以了解它们描述周期性振荡的能力。由于尺寸分布的变宽，普遍接受的用于增殖动力学的简单概念不能维持振荡行为，而模拟表明，新合成细胞壁的有限寿命的建议会减缓向时间不变的平衡状态的松弛速度，达到数十万代。与季节性扰动事件相结合，具有有限寿命的增殖方案能够解释硅藻种群动态的特征性持久节律。因此，生命周期类似于一个钟摆时钟，它需要不时地通过季节性干扰来上发条，而不是由极限环表示的振荡器。
