Gaboriau Théo, Tobias Joseph A, Silvestro Daniele, Salamin Nicolas
Department of Computational Biology, University of Lausanne, Quartier Sorge, Bâtiment Génopode, 1005, Lausanne, Switzerland.
Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire, SL5 7PY, UK.
Syst Biol. 2025 Apr 1;74(2):267-281. doi: 10.1093/sysbio/syae043.
Popular comparative phylogenetic models such as Brownian Motion, Ornstein-Ulhenbeck, and their extensions assume that, at speciation, a trait value is inherited identically by 2 descendant species. This assumption contrasts with models of speciation at a micro-evolutionary scale where descendants' phenotypic distributions are sub-samples of the ancestral distribution. Different speciation mechanisms can lead to a displacement of the ancestral phenotypic mean among descendants and an asymmetric inheritance of the ancestral phenotypic variance. In contrast, even macro-evolutionary models that account for intraspecific variance assume symmetrically conserved inheritance of ancestral phenotypic distribution at speciation. Here, we develop an Asymmetric Brownian Motion model (ABM) that relaxes the assumption of symmetric and conserved inheritance of the ancestral distribution at the time of speciation. The ABM jointly models the evolution of both intra- and inter-specific phenotypic variation. It also infers the mode of phenotypic inheritance at speciation, which can range from a symmetric and conserved inheritance, where descendants inherit the ancestral distribution, to an asymmetric and displaced inheritance, where descendants inherit divergent phenotypic means and variances. To demonstrate this model, we analyze the evolution of beak morphology in Darwin finches, finding evidence of displacement at speciation. The ABM model helps to bridge micro- and macro-evolutionary models of trait evolution by providing a more robust framework for testing the effects of ecological speciation, character displacement, and niche partitioning on trait evolution at the macro-evolutionary scale.
诸如布朗运动、奥恩斯坦-乌伦贝克及其扩展模型等流行的比较系统发育模型假定，在物种形成时，一个性状值由两个后代物种同等继承。这一假设与微观进化尺度上的物种形成模型形成对比，在微观进化尺度上，后代的表型分布是祖先分布的子样本。不同的物种形成机制可能导致祖先表型均值在后代中的位移以及祖先表型方差的不对称遗传。相比之下，即使是考虑种内方差的宏观进化模型也假定在物种形成时祖先表型分布具有对称保守的遗传。在此，我们开发了一种非对称布朗运动模型（ABM），该模型放宽了物种形成时祖先分布对称保守遗传的假设。ABM联合模拟种内和种间表型变异的进化。它还推断物种形成时的表型遗传模式，其范围可以从对称保守遗传（后代继承祖先分布）到不对称位移遗传（后代继承不同的表型均值和方差）。为了演示这个模型，我们分析了达尔文雀喙形态的进化，发现了物种形成时位移的证据。ABM模型通过提供一个更强大的框架来测试生态物种形成、性状置换和生态位划分对宏观进化尺度上性状进化的影响，有助于弥合性状进化的微观和宏观进化模型之间的差距。
