Chromosomal data have been underutilized in phylogenetic investigations despite the obvious potential that cytogenetic studies have to reveal both structural and functional homologies among taxa. In large part this is associated with difficulties in scoring conventional and molecular cytogenetic information for phylogenetic analysis. The manner in which chromosomal data have been used by most authors in the past was often conceptionally flawed in terms of the methods and principles underpinning modern cladistics. We present herein a review of the different methods employed, examine their relative strengths, and then outline a simple approach that considers the chromosomal change as the character, and its presence or absence the character state. We test this using one simulated and several empirical data sets. Features that are unique to cytogenetic investigations, including B-chromosomes, heterochromatic additions/deletions, and the location and number of nucleolar organizer regions (NORs), as well as the weighting of chromosomal characters, are critically discussed with regard to their suitability for phylogenetic reconstruction. We conclude that each of these classes of data have inherent problems that limit their usefulness in phylogenetic analyses and in most of these instances, inclusion should be subject to rigorous appraisal that addresses the criterion of unequivocal homology.

中文翻译：

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细胞遗传学和分支学

尽管细胞遗传学研究具有揭示分类群之间结构和功能同源性的明显潜力，但染色体数据在系统发育研究中并未得到充分利用。在很大程度上，这与对用于系统发育分析的常规和分子细胞遗传学信息进行评分的困难有关。过去大多数作者使用染色体数据的方式在支持现代分支学的方法和原则方面经常存在概念上的缺陷。我们在此回顾所采用的不同方法，检查它们的相对优势，然后概述一个简单的方法，将染色体变化视为特征，并将其存在与否视为特征状态。我们使用一个模拟数据集和几个经验数据集对此进行测试。细胞遗传学研究独有的特征，包括 B 染色体、异染色质添加/缺失、核仁组织者区域 (NOR) 的位置和数量，以及染色体特征的权重，就其对系统发育的适用性进行了批判性讨论。重建。我们得出的结论是，这些类别的数据中的每一个都有固有的问题，限制了它们在系统发育分析中的有用性，并且在大多数情况下，包含应该受到严格的评估，以解决明确同源性的标准。批判性地讨论了它们对系统发育重建的适用性。我们得出的结论是，这些类别的数据中的每一个都有固有的问题，限制了它们在系统发育分析中的有用性，并且在大多数情况下，包含应该受到严格的评估，以解决明确同源性的标准。批判性地讨论了它们对系统发育重建的适用性。我们得出的结论是，这些类别的数据中的每一个都有固有的问题，限制了它们在系统发育分析中的有用性，并且在大多数情况下，包含应该受到严格的评估，以解决明确同源性的标准。