Data from: Restriction site-associated DNA sequencing (RAD-seq) reveals an extraordinary number of transitions among gecko sex-determining systems

Sex chromosomes have evolved many times in animals and studying these replicate evolutionary “experiments” can help broaden our understanding of the general forces driving the origin and evolution of sex chromosomes. However this plan of study has been hindered by the inability to identify the sex chromosome systems in the large number of species with cryptic, homomorphic sex chromosomes. Restriction site-associated DNA sequencing (RAD-seq) is a critical enabling technology that can identify the sex chromosome systems in many species where traditional cytogenetic methods have failed. Using newly generated RAD-seq data from twelve gecko species, along with data from the literature, we reinterpret the evolution of sex-determining systems in lizards and snakes and test the hypothesis that sex chromosomes can routinely act as evolutionary traps. We uncovered between 17 and 25 transitions among gecko sex-determining systems. This is approximately ½ to ⅔ of the total number of transitions observed among all lizards and snakes. We find support for the hypothesis that sex chromosome systems can readily become trap-like and show that adding even a small number of species from understudied clades can greatly enhance hypothesis testing in a model-based phylogenetic framework. RAD-seq will undoubtedly prove useful in evaluating other species for male or female heterogamety, particularly the majority of fish, amphibian, and reptile species that lack visibly heteromorphic sex chromosomes, and will significantly accelerate the pace of biological discovery.性染色体在动物界已独立演化多次，对这类重复出现的进化“实验”开展研究，有助于深化我们对驱动性染色体起源与演化的通用机制的认知。然而，诸多物种的性染色体呈现隐匿性、同形性特征，难以识别其对应的性染色体系统，这一困境长期阻碍了相关研究的推进。限制性酶切位点相关DNA测序（Restriction site-associated DNA sequencing, RAD-seq）是一项关键的支撑技术，可在传统细胞遗传学方法无法奏效的众多物种中，实现性染色体系统的鉴定。本研究结合12种壁虎新生成的RAD-seq数据与公开文献数据集，重新阐释了蜥蜴与蛇类的性别决定系统演化历程，并验证了“性染色体可常规性地充当进化陷阱”这一假说。我们在壁虎的性别决定系统中发现了17至25次演化转换事件，该数量约占所有蜥蜴与蛇类中观测到的总转换事件数的二分之一至三分之二。本研究为“性染色体系统可轻易演变为进化陷阱”的假说提供了支持，并证实：即便仅从研究不足的演化支系中纳入少量物种，也能极大提升基于模型的系统发育框架下的假说检验效能。毋庸置疑，RAD-seq将在评估其他物种的雌雄异配性方面发挥重要作用，尤其是针对绝大多数缺乏明显异形性染色体的鱼类、两栖类与爬行类物种，并将显著加快生物学发现的进程。