ANT LIA: The Role of Sex Determination in the Radiation of Antarctic Notothenioid Fish

ANT LIA：性别决定在南极诺托类鱼类辐射中的作用

• 批准号: 2232891
• 负责人: John Postlethwait
• 金额: $ 191.56万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-15 至 2027-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2232891&HistoricalAwards=false
• 关键词: ANT; LIA; Role; Sex; Determination

Antarctic animals face tremendous threats as Antarctic ice sheets melt and temperatures rise. About 34 million years ago, when Antarctica began to cool, most species of fish became locally extinct. A group called the notothenioids, however, survived due to the evolution of antifreeze. The group eventually split into over 120 species. Why did this group of Antarctic fishes evolve into so many species? One possible reason why a single population splits into two species relates to sex genes and sex chromosomes. Diverging species often have either different sex determining genes (genes that specify whether an individual’s gonads become ovaries or testes) or have different sex chromosomes (chromosomes that differ between males and females within a species, like the human X and Y chromosomes). We know the sex chromosomes of only a few notothenioid species and know the genetic basis for sex determination in none of them. The aims of this research are to: 1) identify sex chromosomes in species representing every major group of Antarctic notothenioid fish; 2) discover possible sex determining genes in every major group of Antarctic notothenioid fish; and 3) find sex chromosomes and possible sex determining genes in two groups of temperate, warmer water, notothenioid fish. These warmer water fish include groups that never experienced the frigid Southern Ocean and groups that had ancestors inhabiting Antarctic oceans that later adjusted to warmer waters. This project will help explain the mechanisms that led to the division of a group of species threatened by climate change. This information is critical to conserve declining populations of Antarctic notothenioids, which are major food sources for other Antarctic species such as bird and seals. The project will offer a diverse group of undergraduates the opportunity to develop a permanent exhibit at the Eugene Science Center Museum. The exhibit will describe the Antarctic environment and explain its rapid climate change. It will also introduce the continent’s bizarre fishes that live below the freezing point of water. The project will collaborate with the university’s Science and Comics Initiative and students in the English Department’s Comics Studies Minor to prepare short graphic novels explaining Antarctic biogeography, icefish specialties, and the science of this project as it develops. As Antarctica cooled, most species disappeared from the continent’s waters, but cryonotothenioid fish radiated into a species flock. What facilitated this radiation? Coyne’s “two rules of speciation” offer explanations for why species diverge: 1) the dysgenic sex in an interspecies hybrid is the one with two different sex chromosomes (i.e., in humans, it would be XY males and not XX females); and 2) “sex chromosomes play an outsized role in speciation”. These ideas propel the project’s main hypothesis: new sex chromosomes and new sex determination genes associate with cryonotothenioid speciation events. The main objective of the research is to identify notothenioid sex chromosomes and candidate sex-determination genes in many notothenioid species.The project’s first aim is to identify Antarctic fish sex chromosomes, asking the question: Did new sex chromosomes accompany speciation events? Knowledge gaps include: which species have cryptic sex chromosomes; which have newly evolved sex chromosomes; and which are chromosomally XX/XY or ZZ/ZW. Methods involve population genomics (RAD-seq and Pool-seq) for more than 20 Antarctic cryonotothenioids. The prediction is frequent turnover of sex chromosomes. The project’s second aim is to Identify candidate Antarctic cryonotothenioid sex-determination genes, asking the question: Did new sex-determination genes accompany Antarctic cryonotothenioid speciation events? A knowledge gap is the identity of sex determination genes in any notothenioid. Preliminary data show that three sex-linked loci are in or adjacent to three different candidate sex determination genes: 1) a duplicate of bmpr1ba in blackfin icefish; 2) a tandem duplicate of gsdf in South Georgia icefish; and 3) a transposed duplicate of gsdf in striped notothen. Methods involve annotating the genomic neighborhoods of cryonotothenioid sex linked loci for anomalies in candidate sex genes, sequencing sex chromosomes, and testing sex gene variants by CRISPR mutagenesis in zebrafish. The prediction is frequent turnover of sex determination genes. The project’s third aim is to identify sex chromosomes and sex-determination genes in temperate notothenioids. Basally diverging temperate notothenioids (‘basals’) lack identifiable sex chromosomes, consistent with temperature-cued sex determination, and one ‘basal’ species is a hermaphrodite. The constantly cold Southern Ocean rules out temperature, a common sex determination cue in many temperate fish, favoring genetic sex determination. Some cryonotothenioids re-invaded temperate waters (‘returnees’). Knowledge gaps include whether basals and returnees have strong sex determination genes. Methods employ pool-seq. The prediction is that genetic sex determination is weak in basals and that returnees have the same, but weaker, sex-linked loci as their Antarctic sister clade. A permanent exhibit will be established at the Eugene Science Center Museum tentatively entitled: The Antarctic: its fishes and climate change. Thousands of visitors, especially school children will be exposed, to the science of Antarctic ecosystems and the impacts of climate change. The research team will collaborate with the university’s Science and Comics Initiative to produce short graphic novels explaining Antarctic biogeography, icefish specialties, and this project.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.

随着南极冰盖的融化和气温的上升，南极动物面临着巨大的威胁。大约3400万年前，当南极洲开始变冷时，大多数鱼类在当地灭绝。然而，一个被称为notothenioids的群体由于防冻剂的进化而幸存下来。最后，这个群体分裂成120多个物种。 为什么这群南极鱼会进化成这么多物种？一个种群分裂成两个物种的一个可能原因与性基因和性染色体有关。不同的物种通常具有不同的性别决定基因（指定个体的性腺是否成为卵巢或睾丸的基因）或具有不同的性染色体（一个物种中男性和女性之间的染色体不同，如人类的X和Y染色体）。我们只知道少数几种南极鱼的性染色体，却不知道它们性别决定的遗传基础。本研究的目的是：1）确定性染色体的物种代表的每一个主要群体的南极notothenioid鱼; 2）发现可能的性别决定基因的每一个主要群体的南极notothenioid鱼;和3）发现性染色体和可能的性别决定基因的两个群体的温带，温暖的水，notothenioid鱼。这些温暖水域的鱼类包括从未经历过寒冷的南大洋的群体，以及祖先居住在南极海洋的群体，后来适应了温暖的沃茨。该项目将有助于解释导致受气候变化威胁的一组物种分裂的机制。这一信息对于保护数量不断减少的南极类南极鱼至关重要，而南极类南极鱼是其他南极物种如鸟类和海豹的主要食物来源。该项目将为不同的本科生群体提供在尤金科学中心博物馆举办永久展览的机会。该展览将描述南极环境，并解释其快速的气候变化。它还将介绍大陆上生活在冰点以下的奇异鱼类。该项目将与该大学的科学和漫画倡议和学生在英语系的漫画研究未成年人合作，准备简短的图形小说解释南极洲地理学，冰鱼专业，以及这个项目的科学，因为它的发展。随着南极洲的变冷，大多数物种从南极洲的沃茨消失，但冷冻鱼类辐射成一个物种群。是什么促成了这种辐射？科因的“物种形成的两个规则”解释了为什么物种会分化：1）种间杂种中的不良性别是具有两个不同性染色体的性别（即，在人类中，它将是XY男性而不是XX女性）;和2）“性染色体在物种形成中起着巨大的作用”。这些想法推动了该项目的主要假设：新的性染色体和新的性别决定基因与cryonotothenioid物种形成事件有关。该研究的主要目的是确定南极鱼类的性染色体和许多南极鱼类物种中的候选性别决定基因。该项目的第一个目标是确定南极鱼类的性染色体，提出一个问题：新的性染色体是否伴随着物种形成事件？知识差距包括：哪些物种具有隐性性染色体;哪些物种具有新进化的性染色体;哪些物种染色体为XX/XY或ZZ/ZW。方法涉及人口基因组学（RAD-seq和Pool-seq）的20多个南极cryonotothenioids。预测是性染色体的频繁更替。该项目的第二个目标是确定候选的南极cryonotothenioid性别决定基因，问的问题：新的性别决定基因伴随南极cryonotothenioid物种形成事件？一个知识缺口是任何notothenioid性别决定基因的身份。初步数据显示，三个性连锁基因座位于或邻近三个不同的候选性别决定基因：1）黑鳍冰鱼中bmpr 1 ba的重复; 2）南格鲁吉亚冰鱼中gsdf的串联重复;和3）条纹南极鱼中gsdf的转座重复。方法涉及注释cryonotothenioid性连锁基因座的基因组邻域以用于候选性基因中的异常，对性染色体进行测序，以及通过斑马鱼中的CRISPR诱变来测试性基因变体。预测是性别决定基因的频繁更替。该项目的第三个目标是鉴定温带类南极鱼的性染色体和性别决定基因。基部分歧温带notothenioids（'basals'）缺乏可识别的性染色体，与温度线索的性别决定一致，和一个'basal'种是雌雄同体。持续寒冷的南大洋排除了温度，这是许多温带鱼类常见的性别决定线索，有利于遗传性别决定。一些cryonotothenioids重新入侵温带沃茨（“回归者”）。知识差距包括基础和回归者是否有强大的性别决定基因。方法采用pool-seq。预测是，基因性别决定是弱的基底和返回者有相同的，但较弱的，性连锁基因座作为他们的南极姐妹分支。将在尤金科学中心博物馆设立一个常设展览，暂定名为：南极：鱼类和气候变化。数以千计的游客，特别是学生，将接触到南极生态系统的科学和气候变化的影响。该研究团队将与该大学的科学和漫画计划合作，制作解释南极地理学、冰鱼特色和该项目的短篇漫画小说。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。