Data from: The evolution of genetic architectures underlying quantitative traits

In the classic view introduced by R. A. Fisher, a quantitative trait is encoded by many loci with small, additive effects. Recent advances in quantitative trait loci mapping have begun to elucidate the genetic architectures underlying vast numbers of phenotypes across diverse taxa, producing observations that sometimes contrast with Fisher's blueprint. Despite these considerable empirical efforts to map the genetic determinants of traits, it remains poorly understood how the genetic architecture of a trait should evolve, or how it depends on the selection pressures on the trait. Here, we develop a simple, population-genetic model for the evolution of genetic architectures. Our model predicts that traits under moderate selection should be encoded by many loci with highly variable effects, whereas traits under either weak or strong selection should be encoded by relatively few loci. We compare these theoretical predictions with qualitative trends in the genetics of human traits, and with systematic data on the genetics of gene expression levels in yeast. Our analysis provides an evolutionary explanation for broad empirical patterns in the genetic basis for traits, and it introduces a single framework that unifies the diversity of observed genetic architectures, ranging from Mendelian to Fisherian.

在R·A·费希尔（R. A. Fisher）提出的经典理论框架中，数量性状由多个效应微小且呈加性的基因座（loci）编码。近年来，数量性状基因座定位技术的进展已开始阐明不同类群中大量表型背后的遗传架构，所得观测结果有时与费希尔的经典理论蓝图相悖。尽管学界已投入大量实证研究以定位性状的遗传决定因子，但人们对性状的遗传架构如何演化，或是其如何受该性状的选择压力影响，仍知之甚少。本研究构建了一个用于阐释遗传架构演化的简约群体遗传学模型。该模型预测：处于中等选择压力下的性状，应由多个效应差异显著的基因座编码；而处于弱选择或强选择压力下的性状，则仅由相对较少的基因座编码。我们将这些理论预测与人类性状遗传学的定性趋势，以及酵母基因表达水平遗传学的系统性数据进行了对比。本研究为性状遗传基础的各类宏观实证模式提供了演化层面的解释，并提出了一个统一框架，可整合从孟德尔式到费希尔式的各类观测到的遗传架构多样性。