Molecular cytogenetic and genomic insights to chromosomal evolution

This review summarizes aspects of the extensive literature on the patterns and processes underpinning chromosomal evolution in vertebrates and especially placental mammals. It highlights the growing synergy between molecular cytogenetics and comparative genomics, particularly with respect to fully or partially sequenced genomes, and provides novel insights into changes in chromosome number and structure across deep division of the vertebrate tree of life. The examination of basal numbers in the deeper branches of the vertebrate tree suggest a haploid (n) chromosome number of 10–13 in an ancestral vertebrate, with modest increases in tetrapods and amniotes most probably by chromosomal fissioning. Information drawn largely from cross-species chromosome painting in the data-dense Placentalia permits the confident reconstruction of an ancestral karyotype comprising n=23 chromosomes that is similarly retained in Boreoeutheria. Using in silico genome-wide scans that include the newly released...本综述系统梳理了支撑脊椎动物（尤其是胎盘类哺乳动物）染色体演化模式与过程的大量相关文献，着重阐明了分子细胞遗传学（molecular cytogenetics）与比较基因组学之间日益深化的协同关系，尤其针对已完成全基因组或部分基因组测序的物种展开探讨，并为脊椎动物生命之树各深层分支的染色体数目与结构变化提供了全新研究视角。通过对脊椎动物生命之树深层分支的基础染色体数目开展分析，结果表明脊椎动物祖先的单倍体（haploid）染色体数目为10~13条，四足动物（tetrapods）与羊膜动物（amniotes）的染色体数目大概率通过染色体断裂（chromosomal fissioning）事件实现了小幅增长。依托主要来自数据富集的胎盘类（Placentalia）中跨物种染色体涂染（cross-species chromosome painting）所获得的信息，我们能够可靠地重建出包含n=23条染色体的祖先核型（karyotype），该核型同样保留于北真兽类（Boreoeutheria）中。通过包含新发布的...在内的全基因组计算机模拟（in silico）扫描分析