Testing gradual and speciational models of evolution in extant taxa: the example of ratites

Ever since Eldredge and Gould proposed their model of punctuated equilibria, evolutionary biologists have debated how often this model is the best description of nature and how important it is compared to the more gradual models of evolution expected from natural selection and the neo-Darwinian paradigm. Recently, Cubo proposed a method to test whether morphological data in extant ratites are more compatible with a gradual or with a speciational model (close to the punctuated equilibrium model). As shown by our simulations, a new method to test the mode of evolution of characters (involving regression of standardized contrasts on their expected standard deviation) is easier to implement and more powerful than the previously proposed method, but the Mesquite module CoMET (aimed at investigating evolutionary models using comparative data) performs better still. Uncertainties in branch length estimates are probably the largest source of potential error. Cubo hypothesized that heterochronic...自埃尔德雷奇（Eldredge）与古尔德（Gould）提出间断平衡模型（punctuated equilibria）以来，进化生物学家们始终围绕该模型在多大程度上最贴合自然真实样貌，以及相较于自然选择与新达尔文主义范式下的渐进式进化模型，其重要性几何这一议题展开争论。近期，库博（Cubo）提出了一种检验方法，用于判断现存平胸总目鸟类（ratites）的形态学数据，更契合渐进式进化模型，还是更接近物种形成模型（即近似于间断平衡模型）。正如我们的模拟实验所证实的那样，一种新的性状进化模式检验方法（通过对标准化对比值（standardized contrasts）与其期望标准差进行回归分析实现），相较于此前提出的方法，更易于实施且检验效力更强；但以比较数据探究进化模型为目标的Mesquite模块CoMET，其表现则更为出色。支长估计的不确定性，或许是潜在误差的最大来源。库博曾提出假说，认为异时性（heterochronic）……