Chromosome numbers have been widely used to describe the most fundamental genomic attribute of an organism or a lineage. Although providing strong phylogenetic signal, chromosome numbers vary remarkably among eukaryotes at all levels of taxonomic resolution. Changes in chromosome numbers regularly serve as indication of major genomic events, most notably polyploidy and dysploidy. Here, we review recent advancements in our ability to make inferences regarding historical events that led to alterations in the number of chromosomes of a lineage. We first describe the mechanistic processes underlying changes in chromosome numbers, focusing on structural chromosomal rearrangements. Then, we focus on experimental procedures, encompassing comparative cytogenomics and genomics approaches, and on computational methodologies that are based on explicit models of chromosome-number evolution. Together, these tools offer valuable predictions regarding historical events that have changed chromosome numbers and genome structures, as well as their phylogenetic and temporal placements.

中文翻译：

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染色体数目的演变：机制模型和实验方法

染色体数已被广泛用于描述生物体或谱系的最基本的基因组属性。尽管提供了强大的系统发育信号，但真核生物的染色体数量在所有分类分辨率水平上都存在显着差异。染色体数量的变化通常作为主要基因组事件的指示，最显着的是多倍体和异倍体。在这里，我们回顾了我们对导致谱系染色体数量改变的历史事件进行推断的能力的最新进展。我们首先描述染色体数量变化的机制过程，重点是结构染色体重排。然后，我们专注于实验程序，包括比较细胞基因组学和基因组学方法，以及基于显式染色体数目进化模型的计算方法。这些工具一起提供了关于改变染色体数量和基因组结构的历史事件及其系统发育和时间位置的有价值的预测。