The Pirbright Institute, Woking, UK.
Ecology and Evolutionary Biology, Brown University, Providence, USA.
Heredity (Edinb). 2018 Nov;121(5):466-481. doi: 10.1038/s41437-018-0110-1. Epub 2018 Jul 11.
In the last years, several genotypic fitness landscapes-combinations of a small number of mutations-have been experimentally resolved. To learn about the general properties of "real" fitness landscapes, it is key to characterize these experimental landscapes via simple measures of their structure, related to evolutionary features. Some of the most relevant measures are based on the selectively acessible paths and their properties. In this paper, we present some measures of evolutionary constraints based on (i) the similarity between accessible paths and (ii) the abundance and characteristics of "chains" of obligatory mutations, that are paths going through genotypes with a single fitter neighbor. These measures have a clear evolutionary interpretation. Furthermore, we show that chains are only weakly correlated to classical measures of epistasis. In fact, some of these measures of constraint are non-monotonic in the amount of epistatic interactions, but have instead a maximum for intermediate values. Finally, we show how these measures shed light on evolutionary constraints and predictability in experimentally resolved landscapes.
在过去的几年中，已经通过实验解决了几个基因型适应度景观——少数突变的组合。为了了解“真实”适应度景观的一般性质，通过与进化特征相关的简单结构度量来对这些实验景观进行特征描述是关键。一些最相关的度量标准基于可访问路径及其特性的相似性。在本文中，我们提出了一些基于（i）可访问路径之间的相似性和（ii）强制性突变的“链”的丰度和特征的进化约束度量，这些链是通过具有单个更适合邻居的基因型的路径。这些度量标准具有明确的进化解释。此外，我们表明链与经典的上位性度量标准相关性较弱。事实上，这些约束度量标准中的一些在数量上与上位性相互作用呈非单调关系，但在中间值处有最大值。最后，我们展示了这些度量标准如何阐明实验解决景观中的进化约束和可预测性。
