OPUS: MCS: Is self-fertilization an evolutionary dead end? Artificial selection of a key outcrossing trait and its consequences in partially selfing populations

理解限制进化和适应的过程仍然是生物学中的一个主要问题。许多植物和动物进化出一些特性，使它们能够通过自花受精来繁殖后代。然而，这种转变被认为是一条单行道，因为自受精限制了基因变异，从而阻止了进一步的进化。该项目将确定主要自交受精的植物是否可以重新进化为异交。对高异交和主要自交的猴花品种进行遗传变异比较，并对决定自交率的花性状进行人工选择。该项目将涉及本科生进行独立实验和分析遗传数据，并将为华盛顿州立大学的一门本科课程开发新的人工选择和遗传进化实验室材料。在以自交为主的种群中，有限的遗传变异被认为是异交性状进化的主要制约因素。虽然近亲繁殖会导致有效种群规模和重组效率的下降，但关于它们对适应性性状进化的影响的信息却很少。在主要自交谱系中，异交性状再进化的限制表明，要么遗传变异是有限的，要么这种反应是可能的，但不太可能发生。为了增加花药-柱头距离这一关键的异交性状，拟用五代人工选择麻瓜异交群体和麻瓜自交群体，确定实现的遗传力。对照系和选择系在实验前后的全基因组测序将揭示选择对其基因组的比较效应。这种全基因组信息有可能将适应性限制与自花受精的遗传后果（即低核苷酸多样性和强连锁不平衡）严格联系起来。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Understanding the processes that limit evolution and adaptation remains a major question in biology. Many plants and animals evolve traits that allow them to produce offspring through self-fertilization. However, this transition is thought to be a one-way street because self-fertilization limits genetic variation which prevents further evolution. This project will determine whether plants that primarily self-fertilize can re-evolve to be outcrossing. Highly outcrossing and primarily selfing species of monkeyflower will be compared for their genetic variation and artificially selected for flower traits that determine the rate of selfing. The project will involve undergraduates in the conduct of independent experiments and the analysis of genetic data, and new laboratory materials will be developed on artificial selection and genetic evolution for an undergraduate course at Washington State University.Limited heritable variation in predominantly selfing populations is thought to be a primary constraint on the evolution of outcrossing traits. While declines in effective population size and the efficacy of recombination are expected with close inbreeding, there is scant information on their consequences for adaptive trait evolution. Constraints on the re-evolution of outcrossing traits in primarily selfing lineages suggest either that genetic variation is limiting or that such responses are possible but unlikely to occur. Outcrossing populations of Mimulus guttatus and selfing populations of M. laciniatus and M. micranthus will be subject to five generations of artificial selection for increasing the anther-stigma distance, a key outcrossing trait, and the realized heritability will be determined. Pooled whole-genome population sequencing of the control and selection lines before and after the experiments will reveal the comparative effects of selection on their genomes. This whole-genome information has the potential to critically link constraints on adaptation to the genetic consequences of self-fertilization (i.e., low nucleotide diversity and strong linkage disequilibrium).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.