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Recombination and the Dynamics of Adaptation in Experimental Saccharomyces Cerevisiae (yeast) Populations

实验酿酒酵母（酵母）群体的重组和适应动态

基本信息

批准号：
1655960
负责人：
Michael Desai
金额：
$ 66.9万
依托单位：
Harvard University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-03-01 至 2020-02-29
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1655960&HistoricalAwards=false
关键词：
Recombination Dynamics Adaptation Experimental Saccharomyces

项目摘要

The vast majority of species, from viruses to complex multicellular organisms, engage in some form of exchange of genetic material between individuals as a component of reproduction. Biologists have long tried to explain why this form of reproduction is so widespread across nature despite substantial costs. One possibility is that mixing up genomes through recombination allows natural selection to act more efficiently. Yet, asexual reproduction should be more efficient: it avoids the costs of finding partners and mating, and allows individuals to pass all (rather than half) of their genetic material to their offspring. This research will test this hypothesis by comparing adaptation in sexual versus asexual yeast populations. In addition to these scientific goals, this work will involve the development and dissemination of curriculum integrating mathematics and biology education. Much recent theoretical attention has focused on the potential for recombination to speed adaptation by bringing together beneficial mutations that occur in different genetic backgrounds, alleviating competition and interference between them. Similarly, recombination can purge deleterious mutations from advantageous genetic backgrounds. However, experimental evidence for these effects is scarce. A few laboratory microbial evolution experiments have shown that recombination can indeed increase the rate of mean fitness increase in adapting populations, but until recently it has been impossible to directly observe the effects of recombination at the genotypic level. This research will quantify how recombination alters the sequence-level dynamics of adaptation in experimental populations of budding yeast, by combining a novel genetic system with high-throughput sequencing methods to characterize how recombination alters the dynamics and outcomes of genomic sequence evolution in laboratory budding yeast populations. This work will then track the long-term fate of sexual reproduction in direct competition with asexuals, to determine how and why sexual reproduction is favored or lost in adapting populations. This project will produce extensive data describing the rate, predictability, and genetic basis of adaptation in laboratory populations that will contribute to the advancement of the field.

绝大多数物种，从病毒到复杂的多细胞生物，都会在个体之间进行某种形式的遗传物质交换，作为繁殖的一部分。长期以来，生物学家一直试图解释为什么这种繁殖方式在自然界中如此普遍，尽管成本高昂。一种可能性是，通过重组混合基因组可以使自然选择更有效地发挥作用。然而，无性繁殖应该更有效：它避免了寻找伴侣和交配的成本，并允许个体将全部（而不是一半）遗传物质传递给后代。这项研究将通过比较有性和无性酵母种群的适应来检验这一假设。除了这些科学目标之外，这项工作还将涉及整合数学和生物教育的课程的开发和传播。最近的许多理论关注都集中在重组通过将不同遗传背景中发生的有益突变聚集在一起、减轻它们之间的竞争和干扰来加速适应的潜力上。同样，重组可以从有利的遗传背景中清除有害突变。然而，这些影响的实验证据很少。一些实验室微生物进化实验表明，重组确实可以提高适应种群的平均适应度增加率，但直到最近，还不可能在基因型水平上直接观察重组的影响。这项研究将通过将新颖的遗传系统与高通量测序方法相结合，来量化重组如何改变出芽酵母实验群体中适应的序列水平动态，以表征重组如何改变实验室出芽酵母群体中基因组序列进化的动态和结果。这项工作将追踪有性生殖与无性生殖直接竞争的长期命运，以确定有性生殖如何以及为何在适应人群中受到青睐或丧失。该项目将产生大量数据，描述实验室群体适应的速率、可预测性和遗传基础，这将有助于该领域的进步。