Bazykin Georgii A
Institute for Information Transmission Problems (Kharkevich Institute) of the Russian Academy of Sciences, Moscow 127051, Russia Faculty of Bioengineering and Bioinformatics and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia Pirogov Russian National Research Medical University, Moscow 117997, Russia
Biol Lett. 2015 Oct;11(10). doi: 10.1098/rsbl.2015.0315.
The fitness landscape-the function that relates genotypes to fitness-and its role in directing evolution are a central object of evolutionary biology. However, its huge dimensionality precludes understanding of even the basic aspects of its shape. One way to approach it is to ask a simpler question: what are the properties of a function that assigns fitness to each possible variant at just one particular site-a single position fitness landscape-and how does it change in the course of evolution? Analyses of genomic data from multiple species and multiple individuals within a species have proved beyond reasonable doubt that fitness functions of positions throughout the genome do themselves change with time, thus shaping protein evolution. Here, I will briefly review the literature that addresses these dynamics, focusing on recent genome-scale analyses of fitness functions of amino acid sites, i.e. vectors of fitnesses of 20 individual amino acid variants at a given position of a protein. The set of amino acids that confer high fitness at a particular position changes with time, and the rate of this change is comparable with the rate at which a position evolves, implying that this process plays a major role in evolutionary dynamics. However, the causes of these changes remain largely unclear.
适应度景观——将基因型与适应度联系起来的函数——及其在引导进化过程中的作用是进化生物学的核心研究对象。然而，其巨大的维度使得人们甚至难以理解其形状的基本方面。一种解决方法是提出一个更简单的问题：为一个特定位点（即单一位点适应度景观）的每个可能变体赋予适应度的函数有哪些属性，以及它在进化过程中如何变化？对来自多个物种以及同一物种内多个个体的基因组数据的分析已经确凿无疑地证明，整个基因组中各位点的适应度函数本身会随时间变化，从而塑造了蛋白质进化。在此，我将简要回顾涉及这些动态变化的文献，重点关注近期对氨基酸位点适应度函数的全基因组规模分析，即在蛋白质特定位置上20种单个氨基酸变体的适应度向量。在特定位置赋予高适应度的氨基酸集合随时间变化，且这种变化的速率与一个位点的进化速率相当，这意味着该过程在进化动态中起主要作用。然而，这些变化的原因在很大程度上仍不清楚。
