Sprecher
Beschreibung
One of the most popular scenarios for the origin of life is as follows. First, organic molecules, such as amino acids and nucleotides, were prebiotically synthesized on the early Earth, forming polymers, peptides, RNA, and so on. Some of the polymers acquired the ability to self-replicate and began Darwinian evolution to become more complex and closer to the extant living organisms. Our research interest is in the later part of this scenario, the complexification process of self-replicating molecules through Darwinian evolution. How do self-replicating molecules evolve to become more complex, closer to existing living organisms? Is the ability of Darwinian evolution sufficient for the emergence of life, or are other conditions required? To answer these questions experimentally, we have constructed a translation-coupled RNA replication system from a genomic RNA encoding an RNA replication enzyme and a reconstituted translation system of E. coli as an experimental model. Through a long-term serial dilution process of the system, we found that a parasitic RNA species lacking the RNA replication enzyme gene emerged and coevolved with the genomic “host” RNA species. Coevolution accelerated the evolution and induced diversification of both host and parasitic RNAs into at least five lineages. Furthermore, the diversified RNAs were initially competitive, but formed a complex, interdependent replication network. These results support that parasitic replicators might play an important role in the diversification and ecological complexification of prebiotic self-replicators.
