Theoretical and experimental evolution on genomes and mating systems

我的研究重点是塑造一个有机体的许多特征的进化力量，包括它的生活史、生殖系统和基因组结构。通过数学建模、实验进化和统计推断，我们的工作有助于解释物种之间显著的多样性，并为预测进化对不断变化的环境的反应提供了更好的基础。在这里，我概述了我的团队将利用NSERC资金完成的研究。 目标一：先进的进化论 我的团队将研究一系列不同的数学模型。作为一个例子，我重点研究了在性生活周期的单倍体和二倍体阶段之间的冲突选择压力(“倍性对立选择”)。 我们正在研究进化如何预测如何塑造单倍体花粉或精子在面对这样的冲突时竞争受精的“选择性竞技场”。这项理论工作通过预测单倍体选择何时可能成为主要的进化力量，填补了一个重要的空白。 我们还将调查倍性拮抗选择如何影响性染色体进化。这一理论有望对基因组中与性别相关的区域中预期的选择签名做出新的预测。 目标二：酵母菌的实验进化 我的实验室将使用酵母来研究物种形成的第一步，研究暴露在新环境中后出现的生殖不亲和性。我们的初步结果显示，在杀菌剂制霉菌素存在的抗性突变中，大约一半的杂交存在生殖不亲和性。 我们提出了三个实验来研究这一令人惊讶的发现： (A)在持续暴露于制霉菌素的情况下进化线条，以确定最初强烈的不亲和性是否保持。 (B)根据更多的环境挑战演变路线，以测试每一轮适应是否进一步导致孤立。 (C)将品系进化到缓慢与快速变化的环境中，以测试不相容是否在大规模突变中比在小规模突变中更常见。 这些实验有望阐明适应最有可能产生新物种的时间。 目标三：比较分析 我的研究小组还研究了跨系统发育树的长期进化过程。 一个悬而未决的方法论问题是如何纠正研究人员选择研究的偏差。小的或不变的有机体群体往往被忽视。目前的方法不能解释这种“收购偏向”。我们将开发出纠正这些偏差的统计方法。 从经验上讲，我们正在对性别制度对多样化的影响进行大规模分析。我们正在分析雌雄异株(不同性别)在生命树上的分布，以检验为什么雌雄异株在一些群体中很常见，而在另一些群体中很少见。

My research focuses on evolutionary forces shaping the many features of an organism, including its life history, reproductive system, and genomic structure. Through mathematical modelling, experimental evolution, and statistical inference, our work helps explain the remarkable diversity among species and provides an improved basis for predicting evolutionary responses to changing environments. Here I outline research that my group will accomplish with NSERC funding. Goal I: Advancing Evolutionary Theory My group will pursue a diverse array of mathematical models. As an example, I highlight research on conflicting selection pressures between haploid and diploid phases of sexual life cycles (“ploidally antagonistic selection”). We are investigating how evolution is predicted to shape the “selective arena” within which haploid pollen or sperm compete for fertilization in the face of such conflicts. This theoretical work fills an important gap by predicting when haploid selection is likely to be a major evolutionary force. We will also investigate how ploidally antagonistic selection impacts sex chromosome evolution. This theory promises to make novel predictions about the signatures of selection expected in sex-linked regions of the genome. Goal II: Experimental Evolution in Yeast My lab will use yeast to investigate the first steps towards speciation, studying reproductive incompatibilities that arise following exposure to a novel environment. Our preliminary results have revealed reproductive incompatibilities in about half of the crosses among resistance mutations that arose in the presence of the fungicide, nystatin. We propose three experiments to investigate this surprising finding: (a) Evolve lines under continued exposure to nystatin to determine whether the initially strong incompatibility is maintained. (b) Evolve lines to additional environmental challenges to test whether each bout of adaptation contributes further to isolation. (c) Evolve lines to a slowly versus rapidly changing environment to test whether incompatibilities arise more commonly among large-scale than small-scale mutations. These experiments promise to shed light on when adaptation is most likely to generate new species. Goal III: Comparative Analyses My research group also investigates long-term evolutionary processes across phylogenetic trees. An open methodological question is how to correct for biases in what researchers choose to study. Small or invariant groups of organisms are often ignored. Current methods do not account for such “acquisition biases”. We will develop statistical methods that correct for these biases. Empirically, we are performing large-scale analyses of the impact of sexual system on diversification. We are analyzing the distribution of dioecy (separate sexes) across the tree of life to test hypotheses for why dioecy is common in some groups but rare in others.