von der Dunk Samuel H A, Colizzi Enrico Sandro, Hogeweg Paulien
Theoretical Biology and Bioinformatics, Utrecht University, 3584 CH Utrecht, The Netherlands.
Life (Basel). 2017 Nov 2;7(4):43. doi: 10.3390/life7040043.
Molecules that replicate in trans are vulnerable to evolutionary extinction because they decrease the catalysis of replication to become more available as a template for replication. This problem can be alleviated with higher-level selection that clusters molecules of the same phenotype, favouring those groups that contain more catalysis. Here, we study a simple replicator model with implicit higher-level selection through space. We ask whether the functionality of such system can be enhanced when molecules reproduce through complementary replication, representing RNA-like replicators. For high diffusion, symmetry breaking between complementary strands occurs: one strand becomes a specialised catalyst and the other a specialised template. In ensemble, such replicators can modulate their catalytic activity depending on their environment, thereby mitigating the conflict between levels of selection. In addition, these replicators are more evolvable, facilitating survival in extreme conditions (i.e., for higher diffusion rates). Our model highlights that evolution with implicit higher-level selection-i.e., as a result of local interactions and spatial patterning-is very flexible. For different diffusion rates, different solutions to the selective conflict arise. Our results support an RNA World by showing that complementary replicators may have various ways to evolve more complexity.
以反式复制的分子容易遭受进化灭绝，因为它们会降低复制的催化作用，从而更易于作为复制模板。通过对相同表型的分子进行聚类的高级选择，青睐那些具有更多催化作用的群体，可以缓解这个问题。在此，我们研究一个通过空间进行隐含高级选择的简单复制子模型。我们探讨当分子通过互补复制进行繁殖时（代表类RNA复制子），这样的系统功能是否能够得到增强。对于高扩散情况，互补链之间会发生对称性破缺：一条链成为专门的催化剂，另一条成为专门的模板。总体而言，这类复制子能够根据其环境调节自身的催化活性，从而减轻选择层次之间的冲突。此外，这些复制子更具进化能力，有助于在极端条件下（即对于更高的扩散速率）存活。我们的模型强调，通过隐含高级选择进行的进化——即由于局部相互作用和空间模式形成的结果——非常灵活。对于不同的扩散速率，会出现针对选择性冲突的不同解决方案。我们的结果通过表明互补复制子可能有多种方式进化出更高的复杂性，支持了RNA世界假说。
