Understanding genetic variation and adaptation in relation to sexual reproduction

一些最多产的动植物物种在大部分时间里进行无性繁殖，很少使用有性繁殖。我的团队将结合理论、实验和基因组学方法，研究很少或没有性行为的进化的后果，以及调查有利于维持性行为的条件。这项实证工作将使用两种兼性生殖系统，浮萍和单性轮虫。*我们将开发理论来理解无性系如何在波动的环境中进化，特别强调选择中的时间自相关性。我们将使用轮虫花瓣臂尾轮虫的无性克隆对这些想法进行实验测试。在另一组实验中，我们将在过去工作的基础上证明，适应环境变化可以在兼性人口中选择更高的性别率。具体地说，我们将扩展和测试预测种群细分在适应期间有利于更高的性别比率的理论。*除了用轮虫进行良好控制的实验室实验外，我们还将通过研究浮萍来研究自然系统中性别的原因和结果。我们已经从两个物种(小浮萍和多根螺旋藻)那里获得了大量的基因组数据，这将使我们能够迅速取得进展。我们将扩展使用序列数据推断性别比率的统计方法，并将这些方法应用于我们的浮萍数据。利用现有的群体遗传学推断方法，我们将从不同群体和物种的基因组数据中估计选择的有效性，并将这些测量与推断的性别比率联系起来，测试性别提高整个基因组选择效率的预测。*浮萍也将被用来测试关于性别进化维持的理论。通过实验创建克隆衍生的基因类型以及性衍生的基因类型，我们将比较来自不同生殖模式的基因类型的适合度分布。这种类型的数据是推断两种一般群体遗传机制中哪一种偏爱性别的关键。我们将在几种不同的现场操作环境下分析适应性，以评估生态制剂(例如，天敌)的重要性，这些生态制剂通常在实验室实验中被排除在外，但对某些假设至关重要。*将为本科生、毕业生和PDF提供大量高质量的培训机会。*

Some of the most prolific plant and animal species reproduce clonally much of the time, using sexual reproduction only rarely. My group will examine the consequences of evolving with little or no sex as well as investigate the conditions favouring the maintenance of sex, using a combination of theoretical, expermimental, and genomic approaches. The empirical work will use two facultatively sexual systems, duckweeds and monogonont rotifers.*** We will develop theory to understand how asexuals evolve in fluctuating environments, with special emphasis on temporal autocorrelations in selection. We will test these ideas experimentally using obligately asexual clones of the rotifer Brachionus calyciflorus. In another set of experiments, we will build upon our past work demonstrating that adaptation to environmental change can select for higher rates of sex within facultatively sexual populations. Specifically, we will extend and test theory predicting that population subdivision favours higher rates of sex during adaptation.*** In addition to well-controlled lab experiments with rotifers, we will examine the causes and consequences of sex in a natural system by studying duckweeds. We have already obtained substantial genomic data from two species (Lemna minor and Spirodela polyrhiza) and this will allow us to make progress rapidly. We will extend statistical methods for inferring rates of sex using sequence data and apply these to our duckweed data. Using existing methods of population genetics inference, we will estimate the efficacy of selection from genomic data in different populations and species and relate these measures to inferred rates of sex, testing the prediction that sex increases the efficacy of selection across the genome.***Duckweed will also be used to test theory on the evolutionary maintenance of sex. By experimentally creating clonally-derived genotypes as well as sexually-derived genotypes, we will compare the fitness distributions of genotypes from different reproductive modes. This type of data is key to inferring which of two general population genetic mechanisms favour sex. We will assay fitness under several different field-manipulated environments to assess the importance of ecological agents (e.g., natural enemies) that are typically excluded in lab experiments but critical to some hypotheses.***Numerous high quality training opportunities will be provided for undergrads, grads, and PDFs.********