Levien Ethan, Min Jiseon, Kondev Jane, Amir Ariel
John A Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, United States of America.
Mathematics, Dartmouth College, Hanover, NH 03755, United States of America.
Rep Prog Phys. 2021 Nov 10;84(11). doi: 10.1088/1361-6633/ac2c92.
The observation that phenotypic variability is ubiquitous in isogenic populations has led to a multitude of experimental and theoretical studies seeking to probe the causes and consequences of this variability. Whether it be in the context of antibiotic treatments or exponential growth in constant environments, non-genetic variability has significant effects on population dynamics. Here, we review research that elucidates the relationship between cell-to-cell variability and population dynamics. After summarizing the relevant experimental observations, we discuss models of bet-hedging and phenotypic switching. In the context of these models, we discuss how switching between phenotypes at the single-cell level can help populations survive in uncertain environments. Next, we review more fine-grained models of phenotypic variability where the relationship between single-cell growth rates, generation times and cell sizes is explicitly considered. Variability in these traits can have significant effects on the population dynamics, even in a constant environment. We show how these effects can be highly sensitive to the underlying model assumptions. We close by discussing a number of open questions, such as how environmental and intrinsic variability interact and what the role of non-genetic variability in evolutionary dynamics is.
在同基因群体中，表型变异性普遍存在，这一观察结果引发了众多实验和理论研究，旨在探究这种变异性的成因及后果。无论是在抗生素治疗的背景下，还是在恒定环境中的指数增长情况下，非遗传变异性都会对种群动态产生重大影响。在此，我们回顾了阐明细胞间变异性与种群动态之间关系的研究。在总结相关实验观察结果后，我们讨论了风险对冲和表型转换模型。在这些模型的背景下，我们讨论了单细胞水平上的表型转换如何帮助种群在不确定的环境中生存。接下来，我们回顾了更精细的表型变异性模型，其中明确考虑了单细胞生长速率、世代时间和细胞大小之间的关系。即使在恒定环境中，这些特征的变异性也会对种群动态产生重大影响。我们展示了这些影响如何对潜在的模型假设高度敏感。最后，我们讨论了一些悬而未决的问题，例如环境变异性和内在变异性如何相互作用，以及非遗传变异性在进化动态中的作用是什么。
