The Genetic Basis of Reduced Sexual Dimporphism for Red Throat Color Evolution in the Threespine Stickleback

描述（由申请人提供）： 性二态性遍及生物学的各个方面，从进化到生理学再到医学。由于两性异形导致男性和女性之间疾病的发病、流行和严重程度的差异，因此在许多情况下，两性异形对于理解和治疗复杂的人类疾病至关重要。然而，对包括人类在内的几乎所有生物体，都缺乏对性二态表型变异的基因组基础的透彻理解。整合基因组和比较进化方法研究性二态性状的研究具有快速进展的潜力。在这里，它建议使用一个新兴的进化和基因组模型，threespine棘鱼（Gasterosteus aculeatus），研究在一个良好的特征的进化背景下的性别二型性的变异的基因组基础。这项研究将阐明男性和女性的装饰物的基因组基础，精心挑选的自然种群，作为一个假设，即雌雄间的遗传相关性主要负责减少性二型性的测试。threespine刺鱼种群之间的进化关系，使这个物种复杂的比较分析特别强大。淡水居民的种群往往是以独立和复制的方式，从祖先的海洋形式。在大多数地区，二型棘鱼最显著的特征之一是雄性喉咙上的橘红色，而不是雌性。然而，麦金农实验室最近发现并开始研究新的溪流居民刺鱼种群，其中雌性刺鱼已经进化出雄性典型的喉咙颜色，两性异形已经减少。因此，雄性化的雌性特征是从海洋种群中的祖先状态演变而来的，在海洋种群中，雄性化的雌性特征是不存在的，但现存的自然种群很容易取样。两性间的遗传相关性预计有一个实质性的影响，这种减少性二型性的演变，然而，在性二型性的变异的遗传基础几乎是未知的。因此，本提案的主要目标是调查性二型性变异的基因组基础，以回答以下问题：性二型性减少是否源于男性和女性之间共享的基因组变异？这项工作将在三个特定目标（SA）上完成，使用最先进的全基因组分析，数量性状基因座（QTL）定位和RNA测序（RNA-seq），以研究与性二态红喉色变化相关的基因组变异。目的1：确定相同的基因组区域是否有助于女性和男性的红喉着色。目标二：使用全转录组分析，测试基因表达模式在性别和趋同人群之间是否相似，以及色彩鲜艳的女性是否广泛男性化。目的3：整合有关QTL和基因表达研究中出现的遗传机制的推论。

DESCRIPTION (provided by applicant): PROJECT SUMMARY Sexual dimorphism pervades all aspects of biology, from evolution to physiology to medicine. Because it contributes to variation in the onset, prevalence, and severity of disease between males and females, sexual dimorphism is in many cases fundamental to understanding and treating complex human diseases. However, a thorough understanding of the genomic basis of variation in sexually dimorphic phenotypes is lacking for almost all organisms, including humans. Studies that integrate genomic and comparative evolutionary approaches to studying sexually dimorphic traits hold potential for rapid progress. Here it is proposed to use an emerging evolutionary and genomic model, the threespine stickleback fish (Gasterosteus aculeatus), to study the genomic basis of variation in sexual dimorphism within a well-characterized evolutionary context. This study will elucidate the genomic underpinnings of male and female ornaments, for carefully chosen natural populations, as a test of the hypothesis that intersexual genetic correlations are mainly responsible for reduced sexual dimorphism. The evolutionary relationships among threespine stickleback populations make this species complex particularly powerful for comparative analyses. Freshwater-resident populations are derived, often in an independent and replicated manner, from the ancestral marine form. In most localities one of the most conspicuously dimorphic stickleback traits is orange-red nuptial coloration on the throats of males but not females. Recently however, the McKinnon laboratory has discovered and begun to study novel populations of stream-resident sticklebacks in which females have evolved the male-typical throat coloration and sexual dimorphism has been reduced. Thus the masculinized female trait has evolved from an ancestral state, in marine populations, in which it is absent but for which extant natural populations are readily sampled. Inter-sexual genetic correlations are expected to have a substantial influence on the evolution of such reduced sexual dimorphism; yet, the genetic basis of variation in sexual dimorphism is almost unknown. Therefore, the primary goal of this proposal is to investigate the genomic basis of variation in sexual dimorphism to answer the question: Does reduced sexual dimorphism result from shared genomic variation between males and females? This work will be accomplished across three specific aims (SA) using state-of-the-art genome wide analyses, quantitative trait loci (QTL) mapping and RNA sequencing (RNA-seq), to study genomic variation associated with variation in sexually dimorphic red throat coloration. Aim 1: Determine whether the same genomic regions contribute to red throat coloration in females and males. Aim 2: Test whether patterns of gene expression are similar between the sexes and convergent populations, and whether colorful females are broadly masculinized, using whole transcriptome analysis. Aim 3: Integrate inferences concerning genetic mechanisms emerging from QTL and gene expression studies.