Xu S
Department of Botany and Plant Sciences, University of California at Riverside, 92521, USA.
Mol Biol Evol. 2000 Jun;17(6):897-907. doi: 10.1093/oxfordjournals.molbev.a026370.
The usual assumption that species have evolved from a common ancestor by a simple branching process--where each branch is genetically isolated--has been challenged by the observation of frequent hybridization between species in natural populations. In fact, most plant species are thought to have hybrid origins. This reticulate pattern of species evolution has posed problems in the definition of speciation and in phylogenetic reconstruction, especially when molecular data are used. As a result, hybridization has been largely treated as an evolutionary accident or statistical error in phylogenetic analysis. In this paper, I explicitly incorporate hybridization as an evolutionary occurrence and then conduct phylogenetic reconstruction. I first examine the reticulate evolution under a pure drift model, and then extend the theory to fit a mutation model. A least-squares method is developed for reconstructing a reticulate phylogeny using gene frequency data. The efficacy of the method under the pure drift model is verified via Monte Carlo simulations.
物种通常是通过简单的分支过程从共同祖先进化而来的——在这个过程中每个分支在基因上都是隔离的——但自然种群中物种间频繁杂交的观察结果对这一假设提出了挑战。事实上，大多数植物物种被认为起源于杂交。这种网状的物种进化模式在物种形成的定义和系统发育重建方面带来了问题，尤其是在使用分子数据时。因此，在系统发育分析中，杂交在很大程度上被视为一种进化意外或统计误差。在本文中，我明确将杂交作为一种进化事件纳入，然后进行系统发育重建。我首先在纯漂变模型下研究网状进化，然后将该理论扩展以适应突变模型。开发了一种使用基因频率数据重建网状系统发育的最小二乘法。通过蒙特卡罗模拟验证了该方法在纯漂变模型下的有效性。
