Evolution of Sex Determination in Sticklebacks

描述（由申请人提供）：性别决定是由初始转换转化为复杂表型的结果，该表型整合了形态学、生理学和行为，以将生物体定义为男性或女性。尽管该途径具有根本重要性，但在自然界中发现了广泛的环境和遗传性别决定机制。密切相关的物种可能具有不同的性染色体互补体，并使用完全不同的机制来决定性别，这表明这些发育途径可以非常迅速地进化。性别决定机制和性染色体的快速进化是如何发生的？刺鱼提供了一个令人兴奋的系统来解决这些问题。最近分化的刺鱼物种具有不同的性染色体互补，也可能使用不同的性别决定机制。已经为刺鱼开发了强大的遗传和基因组工具，使克隆和识别性别决定途径背后的基因成为可能。该提案的目标是：（1）通过该区域的遗传、细胞遗传学和物理图谱来表征三刺刺鱼（Gasterosteus aculeatus）进化中的性染色体上发现的性别决定区域； (2) 通过功能丧失和功能获得的方法从分子水平上鉴定三刺刺鱼的主要性别决定基因； (3)比较近缘刺鱼物种中主性别决定基因的染色体位置，以确定性别决定等级和性染色体在这些物种中是否独立进化。这些研究是实现长期目标的第一步，即比较密切相关物种的性别决定途径，以探索这一基本发育途径的进化，并确定其对生物体形态、生理和行为的影响。

DESCRIPTION (provided by applicant): Sex determination results from the translation of an initial switch into a complex phenotype that integrates morphology, physiology and behavior to define an organism as male or female. Despite the fundamental importance of this pathway, a wide range of both environmental and genetic sex determination mechanisms is found in nature. Closely related species may have different sex chromosome complements and use completely different mechanisms to determine sex, suggesting that these developmental pathways can evolve very rapidly. How can the rapid evolution of sex determination mechanisms and sex chromosomes occur? Stickleback fish provide an exciting system to address these questions. Recently diverged stickleback species have different sex chromosome complements and may also use different sex-determination mechanisms. Powerful genetic and genomic tools, which make it possible to clone and identify the genes underlying sex determination pathways, have been developed for sticklebacks. This goals of this proposal are to: (1) characterize the sex-determination region found on an evolving sex chromosome in threespine sticklebacks (Gasterosteus aculeatus) through genetic, cytogenetic and physical mapping of the region; (2) molecularly identify the master sex-determination gene in threespine sticklebacks through both loss-of-function and gain-of-function approaches; and (3) compare the chromosomal locations of the master sex-determination gene in closely related species of sticklebacks to determine if sex-determination hierarchies and sex chromosomes have evolved independently in these species. These studies are initial steps towards a long-term goal of comparing sex determination pathways in closely related species to explore the evolution of this fundamental developmental pathway and to determine its effects on the morphology, physiology, and behavior of the organism.