Genome Repatterning Underlying the Co-evolution of Diploid Number and Gender Determination in Turtles

大多数动物的性别是由遗传构成决定的（如人类的性别XX/XY染色体，鸟类的性别ZZ/ZW），而其他动物的性别则由环境温度（TSD）决定，包括海龟。值得注意的是，经历了性别决定机制转变的海龟谱系显示染色体数量的进化速度增加了20倍，但目前还不清楚这些特征为什么或如何相关。该项目代表了阐明这两个特征之间的功能联系的第一步，通过测试染色体重排破坏控制性发育的基因的位置和调节的假设，这反过来又导致了海龟性别决定机制之间的转变。通过结合分子细胞遗传学、转录组学、生物信息学和系统发育分析，该项目将重建祖先海龟基因组的结构;描述海龟进化2.1亿年来发生在海龟中的染色体重排;并建立关于性发育调节网络中的关键要素的机械假说，这些要素是性别转变的基础-确定海龟的机制以供进一步研究。该项目提出了一个关于基因组进化与性别决定之间关系的新假设，如果这一假设是正确的，将改变我们对性别决定进化机制的理解。更广泛的影响该项目的教育活动将有助于整合本科生基于发现的学习，并通过培训学生及其导师扩大代表性不足的群体对生物学的参与;通过外展活动吸引妇女和少数群体参与;以及加强PI作为代表性不足群体的榜样的资格。

Gender is determined by genetic constitution in most animals (as by sex XX/XY chromosomes in humans, or ZZ/ZW in birds), and by environmental temperature (TSD) in others, including turtles. Notably, turtle lineages that underwent a transition in the gender-determining mechanism show a 20-fold increase in the rate of evolution of chromosome number, but it is unclear why or how these traits are associated. This project represents the first step to elucidate the functional link between these two traits by testing the hypothesis that chromosomal rearrangements disrupt the location and consequently the regulation of genes controlling sexual development, which in turn cause the transition between gender-determining mechanisms among turtles. By combining molecular cytogenetics, transcriptomics, bioinformatics and phylogenetic analyses, this project will reconstruct the organization of the ancestral turtle genome; characterize the chromosomal rearrangements that have taken place among turtles over 210 million years of turtle evolution; and build mechanistic hypotheses about the critical elements in the regulatory network of sexual development that underlie transitions in gender-determining mechanisms in turtles for further study. This project proposes a novel hypothesis about the relationship of genome evolution over large spans of time and gender determination, which if true, could transform our understanding of the mechanism by which gender determination evolves.Broader ImpactsThe educational activities of this project will help integrate undergraduate discovery-based learning and broaden the participation of underrepresented groups in biology by training students and their mentors; by engaging women and minorities through outreach activities; and by strengthening the PI's qualifications as role model for underrepresented groups.