Evolutionary genetics of sexual dimorphism

理解形成行为、形态和生理上的性别差异的力量是进化生物学的中心难题之一。在一些系统中，我们知道很多关于选择塑造这些特征的力量，而在另一些系统中，我们知道很多关于它们的遗传学。我的提案将重点放在将这些目前不同的项目与三个更具体的主题联系起来。 首先，我们将把发育遗传学和基因组学的新工具带给一个我们对性别特异性选择了解很多的群体。这些工具与我们在团队中的行为和特征功能方面的专业知识相结合，将使我们能够进行真正的综合研究，将选择与功能、发育、表达和基因组进化联系起来。我们将重点放在风湿属上，在那里我们已经确定了一个主要的转录因子，参与在一个物种中建立二态触角特征。我们将对风湿病属的拮抗特性功能进行比较研究，并进行基因敲除，以确定是否有相似的遗传因素支撑着这些不同的特性。野生与基因敲除的表达分析将使我们能够识别与造成这些物种之间观察到的这些特征差异有关的下游基因。 在第二个主题中，我们将开始一个新的项目，研究经济上重要的大型长角甲虫群体的显著性别二形性。在这里，我们将建立一个假设，在这些甲虫的一个大部落的物种之间的关系，并研究该群体的二态进化的历史。随后，我们将测量选择的力量，这可能解释了我们所看到的二相性的变化。 最后，我们将启动对遗传模式物种秀丽线虫的研究，这提供了一个被低估的机会，将现有的基因功能和基因组学知识与目前未被充分研究的性别特异性选择联系起来。使用40个测序的野生分离株，我们的目标是寻找雄性功能及其与两性的共同进化中的进化分歧的迹象。下一步将是寻找驱动这种变异的一些遗传因素，并研究它们的进化。利用现有的工具，我们还计划使用CRISPR/Cas9基因组编辑将一个合成的和性拮抗的基因座插入到一个进化的种群中，带有两个等位基因：一个对男性有害的等位基因和一个对女性有害的等位基因。在对这些种群进行40代实验进化后，我们将量化等位基因频率和种群适应度的变化。我们假设，在一些群体中，通过独立的抑制子突变，拮抗作用将被掩盖，而其他群体可能保持拮抗，甚至积累额外的拮抗等位基因。这个项目将是第一个在未来时间跟踪性对抗位置的经验性研究。

Understanding the forces that shape the, often spectacular, sexual differences in behaviour, morphology, and physiology is one of the central puzzles of evolutionary biology. In some systems, we know much about the forces of selection shaping these traits, while in other systems we know much about their genetics. My proposal will focus on connecting these currently disparate programs with three more specific themes. In the first, we will bring the new tools of developmental genetics and genomics to a group for which we know much about sex specific selection. These tools, combined with our expertise in behaviour and trait function in the group will allow us to do truly integrative research, linking selection to function, development, expression and genome evolution. We will focus on the genus Rheumatobates, where we have identified a major transcription factor involved in building dimorphic antennal traits in one species. We will undertake a comparative study of antagonistic trait function in the genus Rheumatobates, and conduct knockdowns to determine if similar genetic factors underlie these diverse traits. Expression analyses in wild vs knockdowns will allow us to identify the downstream genes involved in creating the differences in these traits observed among species. In the second theme, we will begin a new program studying the remarkable sexual dimorphism of the large and economically important long-horned beetle group. Here, we will develop a hypothesis for the relationships among species in a large tribe of these beetles, and study the history of the evolution of dimorphism in the group. Subsequently, we will measure the forces of selection that may account for the variation in dimorphism that we see. Finally, we will initiate a study of the genetic model species Caenorhabditis elegans, which provides an underappreciated opportunity to link existing knowledge about gene function and genomics to currently understudied sex specific selection. Using 40 sequenced wild isolates we aim to look for signs of evolutionary divergence in male function and its coevolution with hermaphrodites. The next step will be to find some of the genetic factors that drive this variation and study their evolution. Taking advantage of the available tools we also plan to employ CRISPR/Cas9 genome editing to insert a synthetic and sexually antagonistic locus into an evolving population, with two alleles: a male-detrimental allele and a female-detrimental allele. After experimentally evolving these populations for 40 generations, we will quantify changes in allele frequency and population fitness. We hypothesize that antagonism will be masked in some populations through independent suppressor mutations, while others may maintain antagonism and even accumulate additional antagonistic alleles. This project will be the first empirical study to follow a sexually antagonistic locus in forward time.