Theoretical and experimental evolution on genomes and mating systems

我的研究重点是塑造生物体的许多特征的进化力量，包括其生活史，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的显着多样性，并为预测进化对环境变化的反应提供了更好的基础。在这里，我概述了我的团队将在NSERC资助下完成的研究。 目标一：推进进化理论 我的小组将研究各种数学模型。作为一个例子，我强调研究的冲突之间的选择压力的性生活周期的单倍体和二倍体阶段（“倍性拮抗选择”）。 我们正在研究进化是如何预测形成“选择性竞技场”的，在这种冲突面前，单倍体花粉或精子在其中竞争受精。这项理论工作填补了一个重要的空白，预测了单倍体选择何时可能成为一个主要的进化力量。 我们还将研究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性别连锁区域中预期的选择特征做出新的预测。 目标二：酵母的实验进化 我的实验室将使用酵母来研究物种形成的第一步，研究暴露于新环境后出现的生殖不相容性。我们的初步研究结果显示，在大约一半的杂交中，在杀真菌剂制霉菌素的存在下产生的抗性突变之间存在生殖不相容性。 我们提出了三个实验来研究这一惊人的发现： (a)在持续暴露于制霉菌素下进化品系，以确定最初强烈的不相容性是否得以维持。 (b)进化出更多的环境挑战，以测试每一轮适应是否会进一步导致隔离。 (c)将品系进化到缓慢与快速变化的环境中，以测试大规模突变是否比小规模突变更常见不相容性。 这些实验有望揭示什么时候适应最有可能产生新物种。 目标三：比较分析 我的研究小组还研究了系统发育树的长期进化过程。 一个开放的方法论问题是如何纠正研究人员选择研究的偏见。小的或不变的生物群体往往被忽视。目前的方法没有考虑到这种“获取偏差”。我们将开发统计方法来纠正这些偏差。 在实证方面，我们正在进行大规模的分析性别制度对多元化的影响。我们正在分析在整个生命树中的雌雄异株的分布，以检验为什么雌雄异株在某些群体中很常见，而在另一些群体中却很罕见的假设。

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.