Jiang Daohan, Pennell Matt
Department of Quantitative and Computational Biology, University of Southern California, USA.
Macroevolution Unit, Okinawa Institute of Science and Technology Graduate University, Japan.
bioRxiv. 2024 Dec 5:2023.08.11.553044. doi: 10.1101/2023.08.11.553044.
Explaining macroevolutionary divergence in light of population genetics requires understanding the extent to which the patterns of mutational input contribute to long-term trends. In the context of quantitative traits, mutational input is typically described by the mutational variance-covariance matrix, or the -matrix, which summarizes phenotypic variances and covariances introduced by new mutations per generation. However, as a summary statistic, the -matrix does not fully capture all the relevant information from the underlying mutational architecture, and there exist infinitely many possible underlying mutational architectures that give rise to the same -matrix. Using individual-based simulations, we demonstrate mutational architectures that produce the same -matrix can lead to different levels of constraint on evolution and result in difference in within-population genetic variance, between-population divergence, and rate of adaptation. In particular, the rate of adaptation and that of neutral evolution are both reduced when a greater proportion of loci are pleiotropic. Our results reveal that aspects of mutational input not reflected by the -matrix can have a profound impact on long-term evolution, and suggest it is important to take them into account in order to connect patterns of long-term phenotypic evolution to underlying microevolutionary mechanisms.
从群体遗传学的角度解释宏观进化分歧需要了解突变输入模式在多大程度上促成长期趋势。在数量性状的背景下，突变输入通常由突变方差协方差矩阵（即G矩阵）来描述，该矩阵总结了每代新突变引入的表型方差和协方差。然而，作为一个汇总统计量，G矩阵并不能完全捕捉来自潜在突变结构的所有相关信息，并且存在无数种可能的潜在突变结构会产生相同的G矩阵。通过基于个体的模拟，我们证明产生相同G矩阵的突变结构会导致对进化的不同约束水平，并导致种群内遗传方差、种群间分歧和适应率的差异。特别是，当更大比例的基因座具有多效性时，适应率和中性进化率都会降低。我们的结果表明，G矩阵未反映的突变输入方面可能对长期进化产生深远影响，并表明为了将长期表型进化模式与潜在的微观进化机制联系起来，考虑这些方面很重要。
