FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138.
Proc Natl Acad Sci U S A. 2013 Sep 10;110(37):14984-9. doi: 10.1073/pnas.1307604110. Epub 2013 Aug 26.
The origin of life is believed to have progressed through an RNA world, in which RNA acted as both genetic material and functional molecules. The structure of the evolutionary fitness landscape of RNA would determine natural selection for the first functional sequences. Fitness landscapes are the subject of much speculation, but their structure is essentially unknown. Here we describe a comprehensive map of a fitness landscape, exploring nearly all of sequence space, for short RNAs surviving selection in vitro. With the exception of a small evolutionary network, we find that fitness peaks are largely isolated from one another, highlighting the importance of historical contingency and indicating that natural selection would be constrained to local exploration in the RNA world.
生命的起源被认为是通过 RNA 世界逐步发展而来的，在这个世界中，RNA 既充当遗传物质又充当功能分子。RNA 的进化适应度景观的结构将决定第一个功能序列的自然选择。适应度景观是许多推测的主题，但它们的结构基本上是未知的。在这里，我们描述了一个综合的适应度景观图谱，探索了体外选择的短 RNA 的几乎所有序列空间。除了一个小的进化网络之外，我们发现适应度峰值彼此之间基本上是孤立的，这突出了历史偶然性的重要性，并表明在 RNA 世界中，自然选择将受到限制，只能进行局部探索。
