Recombination rate variation and evolution

摘要 减数分裂重组对于减数分裂过程中染色体的适当分离和创造是必要的。 通过等位基因的洗牌来实现种群中的遗传多样性。重组事件数量的变化， 或重组率，因此可以通过减数分裂失败对个体器官健康产生影响，并在 种群适合度通过影响选择的效果来实现。然而，重组率的变化一直是 在整个基因组以及种群和物种之间都有记录。尽管在编目方面取得了进展 重组率的变化，如何以及为什么重组率变化在很大程度上仍然是未知的。的目标是 我的研究计划是调查重组率变异的遗传和环境原因，以及 重组率变异对基因组进化的影响。在未来五年里，我的实验室将使用 酵母菌的实验进化和基因组学探索三个主要问题。首先，如何 重组景观在短时间尺度上的变化？我们正在使用全基因组测序来 构建uvarum酵母多种群全基因组重组率。我们寻求 确定启动重组的双链断裂是如何作为交叉或非交叉修复的 基因转换事件，以及这两种类型的事件是如何在种群之间保守或分化的。 这将是第一次研究在多个种群中这两种重组事件的进化， 为重组率变化的机制提供了前所未有的视角。第二，我们是 研究适应新环境如何改变重组率。复合率塑性 多年来一直与温度和其他环境因素的变化有关，但明确的测试 影响重组率进化的环境适应(反之亦然)缺失。我们将不断进化 实验室中耐寒沙门氏菌种群的耐热性提高，并使用全基因组测序 识别重组率的任何变化或交叉和非交叉基因转化的分布 由于适应温度而发生的事件。最后，我们正在探索重组率如何 影响杂交后渗入在基因组中的分布和持久性。我们 是来自两个部分生殖隔离的不同种群的进化混合菌株来测试 一种假说认为，由于对弱者的选择，在低重组的区域减少了渗入， 负上位性相互作用。我们会将进化种群中的渐渗分布与 重组图更好地理解了是什么力量在杂交后的几代人中塑造了基因组。 总体而言，我的研究将利用使用易驯化的酵母系统的好处来经验性地 测试关于重组如何以及为什么会随着时间的推移而变化的长期假设。

Abstract Meiotic recombination is necessary for the proper segregation of chromosomes during meiosis, and in creating genetic diversity in populations through the shuffling of alleles. Changes in the number of recombination events, or recombination rate, can thus have impacts on individual organismal health via meiotic failure, and on population fitness by influencing the efficacy of selection. And yet, variation in recombination rate has been documented across the genome, and among populations and species. Despite progress in cataloguing recombination rate variation, how and why recombination rate changes remains largely unknown. The goal of my research program is to investigate the genetic and environmental causes of recombination rate variation, and the consequences of recombination rate variation on genome evolution. Over the next five years, my lab will use experimental evolution and genomics in Saccharomyces yeast to explore three main questions. First, how does the recombination landscape change over short time scales? We are using whole genome sequencing to construct genome wide recombination rates in multiple populations of Saccharomyces uvarum. We seek to identify how the double strand breaks that initiate recombination are repaired as crossover or non-crossover gene conversion events, and how these two types of events are conserved or divergent between populations. This will be the first study to examine evolution in both types of recombination events in multiple populations, offering an unprecedented view of the mechanism underlying recombination rate variation. Second, we are investigating how adaptation to a new environment alters recombination rate. Recombination rate plasticity has been linked to changes in temperature and other environmental factors for many years, but explicit tests of environmental adaptation influencing recombination rate evolution (or vice versa) are missing. We will evolve cold tolerant S. uvarum populations in the lab for increased thermotolerance, and use whole genome sequencing to identify any shifts in recombination rate or the distribution of crossover and non-crossover gene conversion events that occur as a result of adaptation to temperature. Finally, we’re exploring how recombination rate influences the distribution and persistence of introgression in the genome following hybridization. We are evolving admixed strains from 2 diverging populations of S. uvarum with partial reproductive isolation to test the hypothesis that introgression is reduced in regions of low recombination due to selection against weak, negative epistatic interactions. We’ll compare the distribution of introgression in evolved populations to recombination maps to better understand what forces shape genomes in the generations after hybridization. Overall, my research will leverage the benefits of working with the tractable Saccharomyces system to empirically test longstanding hypotheses of how and why recombination changes over time.