Supplementary File – Table S4. Updated list of teleost sex chromosome systems including datasets for evaluation of sex chromosome differentiation and comparison with the Tree of Sex database. from Multiple sex chromosomes in teleost fishes from a cytogenetic perspective: state of the art and future challenges

Despite decades of cytogenetic and genomic research of dynamic sex chromosome evolution in teleost fishes, multiple sex chromosomes have been largely neglected. In this review, we compiled available data on teleost multiple sex chromosomes, identified major trends in their evolution and suggest further trajectories in their investigation. In a compiled dataset of 440 verified records of fish sex chromosomes, we counted 75 multiple sex chromosome systems with 60 estimated independent origins. We showed that male-heterogametic systems created by Y-autosome fusion predominate and that multiple sex chromosomes are overrepresented in the order Perciformes. We documented a striking difference in patterns of differentiation of sex chromosomes between male and female heterogamety and hypothesize that faster W sex chromosome differentiation may constrain sex chromosome turnover in female-heterogametic systems. We also found no significant association between the mechanism of multiple sex chromosome formation and percentage of uni-armed chromosomes in teleost karyotype. Last but not least, we hypothesized that interaction between fish populations, which differ in their sex chromosomes, can drive the evolution of multiple sex chromosomes in fishes. This underlines the importance of broader inter-population sampling in studies of fish sex chromosomes.This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)’.

尽管数十年来学界针对硬骨鱼类（teleost fishes）的动态性染色体演化开展了大量细胞遗传学与基因组学研究，但多性染色体系统长期以来被极大程度忽视。本综述整合了已公开的硬骨鱼类多性染色体相关数据，识别出其演化的主要趋势，并为该领域后续研究提出可行方向。在我们整理的包含440条已验证鱼类性染色体记录的数据集中，共统计得到75个多性染色体系统，对应约60个独立起源事件。研究显示，由Y染色体-常染色体融合产生的雄异配系统占据主导，且多性染色体在鲈形目（Perciformes）中显著富集。我们发现雄异配与雌异配类群的性染色体分化模式存在显著差异，并提出假说：W染色体更快的分化速率可能会限制雌异配系统中性染色体的更替。我们还发现，多性染色体的形成机制与硬骨鱼核型中单臂染色体的占比无显著关联。最后同样重要的是，我们提出假说：性染色体组成存在差异的鱼类种群之间的相互作用，可能会推动鱼类多性染色体的演化。这凸显了在鱼类性染色体研究中扩大跨种群采样范围的重要性。本文隶属于主题议题《挑战性染色体演化范式：以脊椎动物为核心的实证与理论洞察（第二部分）》（Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)）的一部分。