Department of Mathematics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
Center for Mathematical Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
PLoS Comput Biol. 2021 Nov 15;17(11):e1009611. doi: 10.1371/journal.pcbi.1009611. eCollection 2021 Nov.
In many models of evolving populations, genetic drift has an outsized role relative to natural selection, or vice versa. While there are many scenarios in which one of these two assumptions is reasonable, intermediate balances between these forces are also biologically relevant. In this study, we consider some natural axioms for modeling intermediate selection intensities, and we explore how to quantify the long-term evolutionary dynamics of such a process. To illustrate the sensitivity of evolutionary dynamics to drift and selection, we show that there can be a "sweet spot" for the balance of these two forces, with sufficient noise for rare mutants to become established and sufficient selection to spread. This balance allows prosocial traits to evolve in evolutionary models that were previously thought to be unconducive to the emergence and spread of altruistic behaviors. Furthermore, the effects of selection intensity on long-run evolutionary outcomes in these settings, such as when there is global competition for reproduction, can be highly non-monotonic. Although intermediate selection intensities (neither weak nor strong) are notoriously difficult to study analytically, they are often biologically relevant; and the results we report suggest that they can elicit novel and rich dynamics in the evolution of prosocial behaviors.
在许多进化群体模型中，遗传漂变相对于自然选择的作用过大，或者反之亦然。虽然有许多情况下这两个假设中的一个是合理的，但这两种力量之间的中间平衡也具有生物学意义。在这项研究中，我们考虑了一些用于模拟中间选择强度的自然公理，并探讨了如何量化这种过程的长期进化动态。为了说明进化动态对漂变和选择的敏感性，我们表明这两种力量之间可能存在一个“最佳平衡点”，即有足够的噪声使稀有突变体得以建立，同时也有足够的选择使它们传播。这种平衡使得亲社会特征能够在以前被认为不利于利他行为出现和传播的进化模型中进化。此外，在这些设置中，选择强度对长期进化结果的影响（既不是弱也不是强）可能高度非单调。尽管中间选择强度（既不强也不弱）很难进行分析，但它们在生物学上往往是相关的；我们报告的结果表明，它们可以在亲社会行为的进化中引发新的和丰富的动态。
