Department of Molecular Biology and Biochemical Engineering, Universidad Pablo de Olavide, Carretera de Utrera km 1, ES-41013 Seville, Spain.
Department of Molecular Biology and Biochemical Engineering, Universidad Pablo de Olavide, Carretera de Utrera km 1, ES-41013 Seville, Spain.
Mol Phylogenet Evol. 2019 Jun;135:203-209. doi: 10.1016/j.ympev.2019.03.006. Epub 2019 Mar 15.
Large-scale changes in chromosome number have been associated with diversification rate shifts in many lineages of plants. For instance, several ancient rounds of polyploidization events have been inferred to promote genomic differentiation and/or isolation and, consequently, angiosperm diversification. Dysploidy, although less studied, has been suggested to also play an important role in angiosperm diversification. In this article, we aim to elucidate the role of chromosomal rearrangements on lineage diversification by analyzing a new comprehensive sedge (Cyperaceae) phylogenetic tree. Our null hypothesis is that the mode and tempo of chromosome evolution are to be homogeneous across the complete phylogeny. In order to discern patterns of diversification shifts and chromosome number changes within the family tree, we tested clade-specific chromosome evolution models for several subtrees according to previously reported increments of diversification rates. Results show that a complex, heterogeneous model composed of different clade-specific chromosome evolution transitions are significantly supported against the null hypothesis of a model with no chromosome number model transition events along the phylogeny. This could suggest a link between diversification and changes in chromosome number evolution although other possibilities are not discarded. Our methodological approach may allow identifying different patterns of chromosome evolution, as found for Cyperaceae, for other lineages at different evolutionary levels.
大规模的染色体数量变化与许多植物谱系的多样化率变化有关。例如，已经推断出几次古老的多倍体化事件促进了基因组分化和/或隔离，从而促进了被子植物的多样化。虽然研究较少，但非整倍体也被认为在被子植物的多样化中起着重要作用。在本文中，我们旨在通过分析一个新的综合性莎草科（莎草科）系统发育树来阐明染色体重排对线系多样化的作用。我们的零假设是，整个系统发育中染色体进化的模式和时标是同质的。为了辨别家族树内多样化转移和染色体数变化的模式，我们根据先前报道的多样化率的增加，对几个亚树测试了特定于分支的染色体进化模型。结果表明，由不同分支特异性染色体进化跃迁组成的复杂、异质模型显著支持了进化过程中没有染色体数模型跃迁的零假设。这可能表明多样化和染色体数量进化的变化之间存在联系，尽管不能排除其他可能性。我们的方法学方法可以识别不同的染色体进化模式，就像在莎草科中发现的那样，对于其他不同进化水平的谱系也是如此。
