Furubayashi Taro, Ichihashi Norikazu
Graduate School of Frontier Biosciences, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
Department of Bioinformatics Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
Life (Basel). 2018 Jan 26;8(1):3. doi: 10.3390/life8010003.
The emergence and dominance of parasitic replicators are among the major hurdles for the proliferation of primitive replicators. Compartmentalization of replicators is proposed to relieve the parasite dominance; however, it remains unclear under what conditions simple compartmentalization uncoupled with internal reaction secures the long-term survival of a population of primitive replicators against incessant parasite emergence. Here, we investigate the sustainability of a compartmentalized host-parasite replicator (CHPR) system undergoing periodic washout-mixing cycles, by constructing a mathematical model and performing extensive simulations. We describe sustainable landscapes of the CHPR system in the parameter space and elucidate the mechanism of phase transitions between sustainable and extinct regions. Our findings revealed that a large population size of compartments, a high mixing intensity, and a modest amount of nutrients are important factors for the robust survival of replicators. We also found two distinctive sustainable phases with different mixing intensities. These results suggest that a population of simple host-parasite replicators assumed before the origin of life can be sustained by a simple compartmentalization with periodic washout-mixing processes.
寄生复制子的出现和主导地位是原始复制子增殖的主要障碍之一。有人提出复制子的区室化可缓解寄生虫的主导地位；然而，目前尚不清楚在何种条件下，与内部反应无关的简单区室化能够确保原始复制子群体在寄生虫不断出现的情况下长期存活。在此，我们通过构建数学模型并进行大量模拟，研究了经历周期性冲洗 - 混合循环的区室化宿主 - 寄生虫复制子（CHPR）系统的可持续性。我们在参数空间中描述了CHPR系统的可持续景观，并阐明了可持续区域和灭绝区域之间的相变机制。我们的研究结果表明，大量的区室、高混合强度和适量的营养物质是复制子稳健存活的重要因素。我们还发现了两个具有不同混合强度的独特可持续阶段。这些结果表明，生命起源之前假设的简单宿主 - 寄生虫复制子群体可以通过具有周期性冲洗 - 混合过程的简单区室化来维持。
