Department of Integrative Biology, University of Texas, Austin, TX 78712, USA.
Milwaukee Public Museum, Milwaukee, WI 53233, USA.
G3 (Bethesda). 2022 Feb 4;12(2). doi: 10.1093/g3journal/jkab435.
The sex chromosomes of the guppy, Poecilia reticulata, and its close relatives are of particular interest: they are much younger than the highly degenerate sex chromosomes of model systems such as humans and Drosophila melanogaster, and they carry many of the genes responsible for the males' dramatic coloration. Over the last decade, several studies have analyzed these sex chromosomes using a variety of approaches including sequencing genomes and transcriptomes, cytology, and linkage mapping. Conflicting conclusions have emerged, in particular concerning the history of the sex chromosomes and the evolution of suppressed recombination between the X and Y. Here, we address these controversies by reviewing the evidence and reanalyzing data. We find no evidence of a nonrecombining sex-determining region or evolutionary strata in P. reticulata. Furthermore, we find that the data most strongly support the hypothesis that the sex-determining regions of 2 close relatives of the guppy, Poecilia wingei and Micropoecilia picta, evolved independently after their lineages diverged. We identify possible causes of conflicting results in previous studies and suggest best practices going forward.
它们比人类和黑腹果蝇等模式生物高度退化的性染色体年轻得多，并且携带许多导致雄性显著颜色的基因。在过去的十年中，已经有几项研究使用多种方法分析了这些性染色体，包括基因组和转录组测序、细胞学和连锁作图。出现了相互矛盾的结论，特别是关于性染色体的历史和 X 染色体和 Y 染色体之间抑制重组的进化。在这里，我们通过回顾证据和重新分析数据来解决这些争议。我们没有发现孔雀鱼的非重组性别决定区域或进化层的证据。此外，我们发现，数据最有力地支持了这样的假设，即孔雀鱼的两个近亲——佩氏无须魮和小鳞无须魮的性别决定区域，在它们的谱系分化后独立进化。我们确定了之前研究中出现冲突结果的可能原因，并提出了未来的最佳实践建议。
