Takeuchi Nobuto, Hogeweg Paulien
Theoretical Biology/Bioinformatics Group, Utrecht University, Utrecht, The Netherlands.
J Mol Evol. 2007 Dec;65(6):668-86. doi: 10.1007/s00239-007-9044-6. Epub 2007 Oct 23.
In the RNA world hypothesis, RNA(-like) self-replicators are suggested as the central player of prebiotic evolution. However, there is a serious problem in the evolution of complexity in such replicators, i.e., the problem of parasites. Parasites, which are replicated by catalytic replicators (catalysts), but do not replicate the others, can destroy a whole replicator system by exploitation. Recently, a theoretical study underlined complex formation between replicators--an often neglected but realistic process--as a stabilizing factor in a replicator system by demonstrating that complex formation can shift the viable range of diffusion intensity to higher values. In the current study, we extend the previous study of complex formation. Firstly, by investigating a well-mixed replicator system, we establish that complex formation gives parasites an implicit advantage over catalysts, which makes the system significantly more vulnerable to parasites. Secondly, by investigating a spatially extended replicator system, we show that the formation of traveling wave patterns plays a crucial role in the stability of the system against parasites, and that because of this the effect of complex formation is not straightforward; i.e., whether complex formation stabilizes or destabilizes the spatial system is a complex function of other parameters. We give a detailed analysis of the spatial system by considering the pattern dynamics of waves. Furthermore, we investigate the effect of deleterious mutations. Surprisingly, high mutation rates can weaken the exploitation of the catalyst by the parasite.
在RNA世界假说中,RNA(类RNA)自我复制分子被认为是前生物进化的核心参与者。然而,这类复制分子在复杂性进化过程中存在一个严重问题,即寄生虫问题。寄生虫由催化复制分子(催化剂)复制,但不会复制其他分子,它们会通过剥削破坏整个复制分子系统。最近,一项理论研究强调了复制分子之间的复合物形成——这一常被忽视但现实的过程——作为复制分子系统中的一个稳定因素,通过证明复合物形成可将扩散强度的可行范围转移到更高值。在当前研究中,我们扩展了之前关于复合物形成的研究。首先,通过研究一个充分混合的复制分子系统,我们确定复合物形成赋予了寄生虫相对于催化剂的隐性优势,这使得系统对寄生虫的脆弱性显著增加。其次,通过研究一个空间扩展的复制分子系统,我们表明行波模式的形成在系统抵御寄生虫的稳定性中起着关键作用,并且正因如此,复合物形成的影响并非直接的;也就是说,复合物形成是使空间系统稳定还是不稳定是其他参数的复杂函数。我们通过考虑波的模式动力学对空间系统进行了详细分析。此外,我们研究了有害突变的影响。令人惊讶的是,高突变率会削弱寄生虫对催化剂的剥削。