Revell Liam J, Collar David C
Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Evolution. 2009 Apr;63(4):1090-100. doi: 10.1111/j.1558-5646.2009.00616.x. Epub 2009 Jan 14.
Many evolutionary processes can lead to a change in the correlation between continuous characters over time or on different branches of a phylogenetic tree. Shifts in genetic or functional constraint, in the selective regime, or in some combination thereof can influence both the evolution of continuous traits and their relation to each other. These changes can often be mapped on a phylogenetic tree to examine their influence on multivariate phenotypic diversification. We propose a new likelihood method to fit multiple evolutionary rate matrices (also called evolutionary variance-covariance matrices) to species data for two or more continuous characters and a phylogeny. The evolutionary rate matrix is a matrix containing the evolutionary rates for individual characters on its diagonal, and the covariances between characters (of which the evolutionary correlations are a function) elsewhere. To illustrate our approach, we apply the method to an empirical dataset consisting of two features of feeding morphology sampled from 28 centrarchid fish species, as well as to data generated via phylogenetic numerical simulations. We find that the method has appropriate type I error, power, and parameter estimation. The approach presented herein is the first to allow for the explicit testing of how and when the evolutionary covariances between characters have changed in the history of a group.
许多进化过程会导致连续性状之间的相关性随时间推移或在系统发育树的不同分支上发生变化。遗传或功能限制的改变、选择机制的改变,或二者的某种组合,都可能影响连续性状的进化及其相互关系。这些变化通常可以映射到系统发育树上,以检验它们对多变量表型多样化的影响。我们提出了一种新的似然方法,用于将多个进化速率矩阵(也称为进化方差 - 协方差矩阵)拟合到两个或更多连续性状的物种数据以及系统发育树上。进化速率矩阵是一个对角线上包含各个性状进化速率,其他位置包含性状间协方差(进化相关性是其函数)的矩阵。为了说明我们的方法,我们将该方法应用于一个实证数据集,该数据集由从28种太阳鱼科鱼类采样的两种摄食形态特征组成,以及通过系统发育数值模拟生成的数据。我们发现该方法具有适当的I型错误、功效和参数估计。本文提出的方法首次允许对性状之间的进化协方差在一个类群的历史中如何以及何时发生变化进行明确检验。