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: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=740692
• 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.

有性生殖很普遍，在大多数动物和一些植物中，涉及两种性别。拟议研究计划的长期目标是了解有性生殖的进化原因和后果，特别是在具有两种性别的系统中。一个中心目标是量化性别选择并了解这种选择产生的各种机制。第二个目标是了解两种不同性别进化的后果。 一组项目的重点是一种有性和无性繁殖的植物——地钱地钱。我们将研究北美不同地区该物种的种群基因组学，以推断种群的有性繁殖频率是否存在差异。如果是这样，我们将推断较高的性行为率是否如预测的那样对选择的功效产生了积极影响。第二组项目旨在了解性别选择，这是进化生物学的一大未知数。完善的理论表明，性别选择应该通过性别如何影响适应度的平均值或方差来发挥作用，但自然界中几乎没有数据评估这些影响。在实地研究中，我们将测量实验产生的有性和无性后代的适应性分布。其他实验将集中于测试选择的关键生态来源。第二组项目侧重于男性和女性之间的差异。选择通常有利于两种性别的不同表型，但这些表型是由一组很大程度上共享的基因构建的。近年来，对许多动物的研究表明，基因表达中的性别二态性很常见，这增加了基因组中的许多基因被选择用于两种性别的不同表达模式的可能性。然而，人们对导致性别偏向基因表达（SBGE）的选择知之甚少。使用实验果蝇种群，我们将检查两种不同进化背景下性别偏向基因表达（SBGE）的变化。首先，我们将研究 SBGE 如何响应配偶竞争的变化而进化，配偶竞争被认为是有利于二态性的主要力量。在第二部分中，我们研究了 SBGE 如何响应一种操纵而进化，这种操纵使大部分基因组主要在一种性别中进化，从而大大减少来自另一种性别的任何冲突选择。这项工作的一个主要目标是更好地了解已经二态性表达的基因是否正在接受更强的二态性选择，以及是否有许多基因当前不是二态性但正在选择成为二态性。总的来说，这些项目将更清晰地描述 SBGE 的进化以及两种不同性别共享基因组进化的后果。