Current understanding of sex chromosome evolution is largely dependent on species with highly degenerated, heteromorphic sex chromosomes, but by studying species with recently evolved or morphologically indistinct sex chromosomes we can greatly increase our understanding of sex chromosome origins, degeneration and turnover. Here, we examine sex chromosome evolution and stability in the gecko genus Aristelliger. We used RADseq to identify sex‐specific markers and show that four Aristelliger species, spanning the phylogenetic breadth of the genus, share a conserved ZZ/ZW system syntenic with avian chromosome 2. These conserved sex chromosomes contrast with many other gecko sex chromosome systems by showing a degree of stability among a group known for its dynamic sex‐determining mechanisms. Cytogenetic data from A. expectatus revealed homomorphic sex chromosomes with an accumulation of repetitive elements on the W chromosome. Taken together, the large number of female‐specific A. praesignis RAD markers and the accumulation of repetitive DNA on the A. expectatus W karyotype suggest that the Z and W chromosomes are highly differentiated despite their overall morphological similarity. We discuss this paradoxical situation and suggest that it may, in fact, be common in many animal species.

中文翻译：

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加勒比呱呱壁虎 (Aristelliger : Sphaerodactylidae) 中保守的 ZZ/ZW 性染色体

目前对性染色体进化的理解很大程度上取决于具有高度退化、异形性染色体的物种，但通过研究具有最近进化或形态学上不明确的性染色体的物种，我们可以大大增加我们对性染色体起源、退化和周转的理解。在这里，我们研究了壁虎属 Aristelliger 的性染色体进化和稳定性。我们使用 RADseq 来鉴定性别特异性标记，并表明四个 Aristelliger 物种跨越该属的系统发育范围，与鸟类 2 号染色体共享一个保守的 ZZ/ZW 系统。这些保守的性染色体与许多其他壁虎性染色体系统形成对比在以其动态性别决定机制而闻名的群体中表现出一定程度的稳定性。A. 细胞遗传学数据 expectatus 揭示了同态性染色体，在 W 染色体上积累了重复元素。总之，大量女性特异性 A. praesignis RAD 标记和 A. expectatus W 核型上重复 DNA 的积累表明 Z 和 W 染色体尽管整体形态相似，但仍高度分化。我们讨论了这种矛盾的情况，并认为它实际上可能在许多动物物种中很常见。