Yeates Jessica A M, Hilbe Christian, Zwick Martin, Nowak Martin A, Lehman Niles
Department of Chemistry, Portland State University, Portland, OR 97207;
Program for Evolutionary Dynamics, Harvard University, Cambridge, MA 02138;
Proc Natl Acad Sci U S A. 2016 May 3;113(18):5030-5. doi: 10.1073/pnas.1525273113. Epub 2016 Apr 18.
Many origins-of-life scenarios depict a situation in which there are common and potentially scarce resources needed by molecules that compete for survival and reproduction. The dynamics of RNA assembly in a complex mixture of sequences is a frequency-dependent process and mimics such scenarios. By synthesizing Azoarcus ribozyme genotypes that differ in their single-nucleotide interactions with other genotypes, we can create molecules that interact among each other to reproduce. Pairwise interplays between RNAs involve both cooperation and selfishness, quantifiable in a 2 × 2 payoff matrix. We show that a simple model of differential equations based on chemical kinetics accurately predicts the outcomes of these molecular competitions using simple rate inputs into these matrices. In some cases, we find that mixtures of different RNAs reproduce much better than each RNA type alone, reflecting a molecular form of reciprocal cooperation. We also demonstrate that three RNA genotypes can stably coexist in a rock-paper-scissors analog. Our experiments suggest a new type of evolutionary game dynamics, called prelife game dynamics or chemical game dynamics. These operate without template-directed replication, illustrating how small networks of RNAs could have developed and evolved in an RNA world.
分子生存和繁殖所需的资源是常见的，但可能很稀缺，分子们会为这些资源展开竞争。在复杂的序列混合物中，RNA组装的动力学是一个频率依赖过程，并且模拟了这种情形。通过合成与其他基因型在单核苷酸相互作用上存在差异的固氮弧菌核酶基因型，我们能够创造出相互作用以实现自我复制的分子。RNA之间的两两相互作用涉及合作与自私行为，这可以在一个2×2收益矩阵中进行量化。我们表明，基于化学动力学的简单微分方程模型，利用输入到这些矩阵中的简单速率，就能准确预测这些分子竞争的结果。在某些情况下，我们发现不同RNA的混合物比单独的每种RNA类型复制得要好得多，这反映了一种相互合作的分子形式。我们还证明，三种RNA基因型可以在类似石头剪刀布的模式中稳定共存。我们的实验提出了一种新型的进化博弈动力学，称为前生命博弈动力学或化学博弈动力学。这些动力学在没有模板导向复制的情况下运行，说明了RNA小网络在RNA世界中可能是如何发展和进化的。
