Evolutionary Ecology of sex-ratio variation in Tigriopus

虎鱼性别比例变异的进化生态学

• 批准号: RGPIN-2015-06224
• 负责人: Anholt, Bradley
• 金额: $ 2.33万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=614019
• 关键词: Evolutionary; Ecology; sex; ratio; variation

Understanding why sex ratio is usually equal and predicting when it should deviate from equality is one of the success stories of evolutionary biology. However, in diploid organisms there is very little variation for sex ratio so the supporting data is almost all observational. The small crustacean copepod Tigriopus californicus has heritable variation for sex ratio and extraordinarily wide phenotypic variation in sex ratio. It produces its first eggs three weeks after hatching, and females mate only once, which makes sequential clutches full sibs.  This makes it ideal to test sex ratio theory experimentally. This animal lives in the splash zone above the high tide line in small pools that frequently dry out. Populations are maintained by frequent dispersal. They are easily maintained in the laboratory and experimental breeding programs are easy to implement.  My research group has been able to  create selected lines that are reliably biased towards producing male or female biased clutches of offspring.  A Quantitative Trait Locus study showed that there are at least 6 loci on 5 (of 12) chromosomes that are significantly associated with clutch sex ratio. This research program seeks to accomplish the following. 1) Understand the unusual features of the Tigriopus sex-determination system. 2) Determine whether population subdivision maintains the wide variation in sex ratio seen in Tigriopus using both theoretical and experimental approaches.   3) Use experimental evolution to test the predictions of sex-ratio theory.  Studies of experimental evolution will be supplemented with high-throughput genomic methods to ascertain whether there are repeatable patterns in the genetic changes associated with evolutionary changes in the sex-ratio phenotype.

理解为什么性别比例通常是平等的，并预测它何时应该偏离平等，是进化生物学的成功故事之一。然而，在二倍体生物体中，性别比例的变化很小，因此支持数据几乎都是观察性的。小型甲壳类桡足类虎虎具有可遗传的性别比变异和极大的性别比表型变异。它在孵化三周后产下第一个卵，雌性只交配一次，这使得连续的幼崽完全是同胞。这使得从实验上检验性别比理论变得非常理想。这种动物生活在涨潮线以上的飞溅区，在经常干涸的小池塘里。种群通过频繁的扩散来维持。它们很容易在实验室维护，实验育种计划也很容易实施。我的研究小组已经能够创造出精选的品系，这些品系可靠地偏向于生产雄性或雌性有偏见的后代。一项数量性状基因座研究表明，在12条染色体中，有5条染色体上至少有6个基因座与产卵性比显著相关。 这项研究计划寻求实现以下目标。1)了解虎鲸性别决定系统的不同寻常的特征。2)用理论和实验两种方法确定种群细分是否保持了老虎性别比的广泛变化。(3)使用实验进化来验证性别比理论的预测。实验进化的研究将得到高通量基因组方法的补充，以确定与性别比表型进化变化相关的遗传变化是否存在可重复的模式。