2026-05-08 東京大学,早稲田大学
攪拌が稀な環境と頻繁な環境でのRNAの長期進化実験は全く異なる進化的結果をもたらした
＜関連情報＞
- https://www.c.u-tokyo.ac.jp/info/news/topics/20260508130000.html
- https://academic.oup.com/mbe/article/43/5/msag084/8666424?login=false
分子宿主-寄生体システムにおける絶滅への実験的進化 Experimental evolution toward extinction in a molecular host–parasite system
Kohtoh Yukawa ,Tomoaki Yoshiyama ,Ryo Mizuuchi ,Norikazu Ichihashi
Molecular Biology and Evolution Published:08 May 2026
DOI:https://doi.org/10.1093/molbev/msag084
Abstract
Theoretical studies have proposed that coevolution with parasitic replicators plays a critical role in the evolution of primitive life; however, experimental verification of the potential outcomes of such coevolutionary dynamics remains limited. We previously conducted a coevolutionary experiment using an RNA–protein replication system that resulted in the spontaneous diversification of host and parasitic RNAs into five distinct lineages with robust coreplication. Here, we report contrasting evolutionary outcomes from a second long-term coevolutionary experiment. Using a droplet flow reactor (FR) system with increased dilution frequency over 5,000 h (1,600 generations), we observed reduced diversity and frequent extinctions in later experimental stages. Coreplication assays of RNA clones revealed that the primary cause of this diversity loss was the shortened reaction time resulting from frequent dilution. Further analysis of RNA clones that emerged during evolution suggested that the frequent extinctions resulted from the appearance of highly competitive parasite species and the dominance of host species that exhibited reduced replication ability. These findings demonstrate that coevolution between host and parasitic replicators can result in diversity loss and frequent extinctions depending on dilution conditions, highlighting the critical role of environmental parameters, such as dilution ratio and frequency, in enabling primitive replicators to evolve sustainably toward the emergence of life.
