The evolutionary causes and consequences of sex and sexual dimorphism

性别和性二态性的进化原因和后果

• 批准号: RGPIN-2020-05629
• 负责人: Agrawal, Aneil
• 金额: $ 4.74万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=751436
• 关键词: evolutionary; causes; consequences; sex; sexual

Sexual reproduction is widespread and, in most animals and some plants, involves two sexes. The long-term objective of the proposed research program is to understand the evolutionary causes and consequences of sexual reproduction, especially in systems with two sexes. One central aim is to quantify selection on sex and understand the various mechanisms by which this selection arises. The second aim is to understand the consequences of evolving with two separate sexes. One set of projects focuses on a plant that reproduces both sexually and asexually, the liverwort Marchantia polymorpha. We will study the population genomics of this species from different regions of North America to infer if populations vary in how frequently they reproduce sexually. If so, we will then infer whether higher rates of sex have positively influenced the efficacy of selection, as predicted. A second set of projects aims to understand selection on sex, one of the great unknowns of evolutionary biology. Well-established theory shows that selection on sex should work through how sex affects either the mean or the variance in fitness, yet there is almost no data evaluating these effects in nature. In a field study, we will measure the distribution of fitness of experimentally generated sexually- and asexually-derived offspring. Additional experiments will focus on testing key ecological sources of selection. A second set of projects focuses on differences between males and females. Selection often favours different phenotypes in the two sexes, yet these phenotypes are constructed from a largely shared set of genes. In recent years, studies in many animals have shown sexual dimorphism in gene expression is common, raising the possibility that many genes in the genome are selected for different expression patterns in the two sexes. However, the selection responsible for creating sex-biased gene expression (SBGE) is poorly understood. Using experimental fruit fly populations, we will examine changes in sex-biased gene expression (SBGE) in two different evolutionary contexts. In the first, we will examine how SBGE evolves in response to changes in mate competition, which is thought to be a major force favouring dimorphism. In the second, we examine how SBGE evolves in response to a manipulation that keeps a large portion of the genome evolving mostly in one sex, thereby greatly diminishing any conflicting selection from the other sex. One major goal of this work is to better understand whether genes that are already dimorphically expressed are under on-going selection for even stronger dimorphism and whether there are many genes that are not currently dimorphic but are under selection to become so. Collectively, the projects will provide a clearer picture of the evolution of SBGE and the consequences of evolving with a genome shared by two different sexes.

有性繁殖是广泛的，在大多数动物和某些植物中，有两个性别。拟议的研究计划的长期目标是了解有性繁殖的进化原因和后果，尤其是在有两个性别的系统中。一个核心目的是量化性别的选择，并了解这种选择的各种机制。第二个目的是了解两个单独的性别的后果。 一组项目的重点是在性和无性繁殖的植物上，即利弗沃特·马尔坦蒂亚多晶。我们将研究北美不同地区的该物种的种群基因组学，以推断出种群在性繁殖的频率上有所不同。如果是这样，我们将推断出较高的性别率是否正如预测的那样，是否对选择的疗效产生了积极影响。第二组项目旨在了解性别的选择，这是进化生物学的伟大未知数之一。完善的理论表明，对性的选择应通过性别如何影响健身的平均值或差异来发挥作用，但是几乎没有数据评估自然界的这些影响。在一项现场研究中，我们将衡量实验性产生的性和无性衍生后代的适应性分布。其他实验将着重于测试关键选择的选择来源。第二组项目的重点是男性和女性之间的差异。选择通常有利于两个性别中的不同表型，但是这些表型是由一组共同的基因组构成的。近年来，许多动物的研究表明，基因表达中的性二态性很常见，这增加了基因组中的许多基因在两性中选择不同表达模式的可能性。但是，对产生性别偏见的基因表达（SBGE）的选择知之甚少。使用实验果蝇种群，我们将在两个不同的进化环境中检查性偏置基因表达（SBGE）的变化。首先，我们将研究SBGE如何反应伴侣竞争的变化，这被认为是有利于二态性的主要力量。在第二个中，我们研究了SBGE是如何响应一种使基因组中很大一部分基因组大部分在一种性别中演变而来的，从而大大减少了其他性别的任何相互矛盾的选择。这项工作的一个主要目标是更好地理解已经表达的二态性基因是否在不断的选择中，以实现更强的二态性，以及是否有许多基因当前不是二态，但正在选择的基因。总的来说，这些项目将更清楚地了解SBGE的演变以及通过两个不同性别共享的基因组进化的后果。