Department Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
Philos Trans R Soc Lond B Biol Sci. 2018 May 26;373(1747). doi: 10.1098/rstb.2017.0105.
Populations of organisms show genetic differences called polymorphisms. Understanding the effects of polymorphisms is important for biology and medicine. Here, we ask which polymorphisms occur at high frequency when organisms evolve under trade-offs between multiple tasks. Multiple tasks present a problem, because it is not possible to be optimal at all tasks simultaneously and hence compromises are necessary. Recent work indicates that trade-offs lead to a simple geometry of phenotypes in the space of traits: phenotypes fall on the Pareto front, which is shaped as a polytope: a line, triangle, tetrahedron etc. The vertices of these polytopes are the optimal phenotypes for a single task. Up to now, work on this Pareto approach has not considered its genetic underpinnings. Here, we address this by asking how the polymorphism structure of a population is affected by evolution under trade-offs. We simulate a multi-task selection scenario, in which the population evolves to the Pareto front: the line segment between two archetypes or the triangle between three archetypes. We find that polymorphisms that become prevalent in the population have pleiotropic phenotypic effects that align with the Pareto front. Similarly, epistatic effects between prevalent polymorphisms are parallel to the front. Alignment with the front occurs also for asexual mating. Alignment is reduced when drift or linkage is strong, and is replaced by a more complex structure in which many perpendicular allele effects cancel out. Aligned polymorphism structure allows mating to produce offspring that stand a good chance of being optimal multi-taskers in at least one of the locales available to the species.This article is part of the theme issue 'Self-organization in cell biology'.
生物种群表现出称为多态性的遗传差异。了解多态性的影响对于生物学和医学很重要。在这里，我们提出了这样一个问题：当生物体在多个任务之间的权衡中进化时，哪些多态性会高频出现。多个任务是一个问题，因为不可能同时在所有任务上都达到最优，因此需要妥协。最近的工作表明，权衡导致了在性状空间中表型的简单几何形状：表型落在 Pareto 前沿上，Pareto 前沿呈多面体形状：一条线、一个三角形、一个四面体等。这些多面体的顶点是单个任务的最优表型。到目前为止，这项 Pareto 方法的研究还没有考虑其遗传基础。在这里，我们通过询问在权衡下进化时种群的多态性结构如何受到影响来解决这个问题。我们模拟了一个多任务选择场景，在这个场景中，种群进化到 Pareto 前沿：两个原型之间的线段或三个原型之间的三角形。我们发现，在种群中变得流行的多态性具有与 Pareto 前沿一致的多效表型效应。同样，流行多态性之间的上位效应与前沿平行。无性交配也与前沿对齐。当漂变或连锁较强时，对齐会减少，取而代之的是一种更复杂的结构，其中许多垂直的等位基因效应相互抵消。对齐的多态性结构允许交配产生后代，这些后代在物种可用的至少一个栖息地中成为优秀的多任务者的机会很大。本文是“细胞生物学中的自组织”主题特刊的一部分。
