Sex Chromosome Evolution in Lizards and Snakes

性染色体通过控制个体的性别在许多动物物种的胚胎发育中起着重要作用。然而，大多数动物的性染色体仍然是未知的，限制了我们对性染色体进化的广泛模式的理解。该项目将通过调查蜥蜴和蛇来推进性染色体进化的研究。这些爬行动物有各种各样的性别决定系统，其中有许多进化转变。这些独立衍生的系统中的每一个都可以作为重复的进化“实验”，以测试控制性染色体进化的一般原则和过程。这项研究将通过识别这些研究不足的爬行动物的性染色体来填补我们知识的空白，然后使用这些数据来表征性染色体进化的一些一般特性。该研究将对博士后研究人员和学生（包括博士生和本科生）进行基因组学和生物信息学方面的培训，这些技能是农业、生物技术和医疗保健职业的高需求技能。研究人员将开发几种爬行动物的基因性别测试。这些测试对于濒危物种的管理和繁殖以及发育研究中胚胎材料的性别鉴定非常重要。研究人员将通过博物馆展览和宠物爬行动物贸易展上的摊位，向宠物爬行动物爱好者和公众宣传遗传学、进化和性染色体。对动物群体（如蜥蜴和蛇）的性染色体进行比较研究，这些动物群体的性别决定机制之间存在重复转换，这有助于回答长期存在的关于性染色体进化的问题。本研究将整合比较基因组学、转录组学和遗传学，以提高蜥蜴和蛇作为研究性染色体进化的模型分支的实用性，并解决以下问题：1）性染色体是进化陷阱吗？2)是不是有些染色体特别适合作为性染色体？3)性染色体剂量补偿在XX/XY和ZZ/ZW分类群中更可能进化吗？4)在抑制性染色体之间的重组方面，重排与性别偏向重组的相对作用是什么？完成后，该项目将能够对驱动蜥蜴和蛇性染色体进化的机制进行后续研究，并建立一个对整个生命树的性染色体进化进行比较分析的框架。该项目收集的数据将对其他科学家有广泛的用途，包括多种蜥蜴和蛇物种的新的高质量基因组组装。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Sex chromosomes play an important role in the embryonic development of many animal species by controlling an individual's sex. However, the sex chromosomes of most animals remain unidentified limiting our understanding of broad patterns of sex chromosome evolution. This project will advance the study of sex chromosome evolution by investigating lizards and snakes. These reptiles have a variety of sex-determining systems with numerous evolutionary transitions among them. Each of these independently derived systems can act as a replicate evolutionary “experiment” to test the general principles and processes that govern sex chromosome evolution. This research will fill gaps in our knowledge by identifying sex chromosomes in these under-studied reptiles and then use these data to characterize some general properties of sex chromosome evolution. The research will train a postdoctoral researcher and students, including PhD students and undergraduates, in genomics and bioinformatics, skills that are in high demand for careers in agriculture, biotechnology, and health care. Researchers will develop genetic sex tests for several reptile species. Such tests are important for the management and breeding of endangered species and sexing embryonic material in developmental research. Researchers will engage in outreach to pet reptile hobbyists and the general public about genetics, evolution, and sex chromosomes via a museum exhibit and a booth at pet reptile trade shows.Comparative studies of sex chromosomes in animal groups with repeated transitions among sex-determining mechanisms, like the lizards and snakes, can help answer longstanding questions about sex chromosome evolution. This research will integrate comparative genomics, transcriptomics, and phylogenetics to enhance the utility of lizards and snakes as a model clade to investigate sex chromosome evolution and address the following questions: 1) Are sex chromosomes an evolutionary trap? 2) Are some chromosomes particularly good at being sex chromosomes? 3) Is sex chromosome dosage compensation more likely to evolve in XX/XY vs. ZZ/ZW taxa? 4) What is the relative role of rearrangements vs. sex-biased recombination in suppressing recombination between the sex chromosomes? Upon completion, this project will enable subsequent investigations into the mechanisms that drive sex chromosome evolution in lizards and snakes and establish a framework for comparative analyses of sex chromosome evolution across the tree of life. Data collected for this project will have broad utility to other scientists, including new, high quality genome assemblies for multiple lizard and snake species.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.