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，特别是在两性系统中。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。第二个目的是了解进化出两种不同性别的后果。 其中一组项目的重点是一种既有性繁殖又无性繁殖的植物，地钱。我们将研究来自北美不同地区的该物种的种群基因组学，以推断种群是否在有性繁殖的频率上存在差异。如果是这样的话，我们就可以推断出较高的性别比例是否如预测的那样对选择的有效性产生了积极的影响。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。成熟的理论表明，性别选择应该通过性别如何影响适应度的均值或方差来起作用，但在自然界中几乎没有数据评估这些影响。在一项实地研究中，我们将测量实验产生的有性和无性后代的适应性分布。更多的实验将侧重于测试选择的关键生态来源。第二组项目侧重于男女之间的差异。自然选择往往会偏爱两性的不同表型，但这些表型是由一组基本上相同的基因构成的。近年来，在许多动物中的研究表明，基因表达的性别二态性是常见的，这增加了基因组中许多基因在两性中选择不同表达模式的可能性。然而，负责创建性别偏向基因表达（SBGE）的选择知之甚少。使用实验果蝇种群，我们将研究性别偏见的基因表达（SBGE）在两个不同的进化背景下的变化。在第一，我们将研究如何SBGE演变在应对配偶竞争的变化，这被认为是一个主要的力量有利于二型性。在第二部分中，我们研究了SBGE如何进化以应对一种操纵，这种操纵使基因组的大部分主要在一种性别中进化，从而大大减少了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表达的基因是否正在进行更强的二态性选择，以及是否有许多基因目前不是二态性的，但正在进行选择。总的来说，这些项目将更清楚地了解SBGE的进化以及两种不同性别共享基因组的进化后果。