Rosas Alexandre, Fontanari José F
Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, São Carlos SP, Brazil.
Orig Life Evol Biosph. 2003 Oct;33(4-5):357-74. doi: 10.1023/a:1025750806233.
We re-examine the problem of the evolution of protein synthesis or enzyme production using a stochastic cellular automaton model, where the replicators are fixed in the sites of a two-dimensional square lattice. In contrast with the classical chemical kinetics or mean-field predictions, we show that a small colony of mutant, protein-mediated (enzymatic) replicators has an appreciable probability to take over a resident population of simpler, direct-template replicators. In addition, we argue that the threshold phenomenon corresponding to the onset of invasion can be described quantitatively within the physics framework of nonequilibrium phase transitions. We study also the invasion of a resident population of enzymatic replicators by more efficient replicators of the same kind, and show that although slightly more efficient mutants cannot invade, invasion is a likely event if the productivity advantage of the mutants is large. In this sense, the establishment of a population of enzymatic replicators is not a 'once-forever' evolutionary decision.
我们使用随机细胞自动机模型重新审视蛋白质合成或酶产生的进化问题，其中复制因子固定在二维方形晶格的位点上。与经典化学动力学或平均场预测不同，我们表明一小群突变的、蛋白质介导（酶促）的复制因子有相当大的概率取代较简单的直接模板复制因子的常驻群体。此外，我们认为对应于入侵开始的阈值现象可以在非平衡相变的物理框架内进行定量描述。我们还研究了同一类更高效的复制因子对酶促复制因子常驻群体的入侵，并表明尽管效率略高的突变体无法入侵，但如果突变体的生产力优势很大，入侵是很可能发生的。从这个意义上说，酶促复制因子群体的建立不是一个“一劳永逸”的进化决定。
