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的特征使它们能够通过自体受精产生后代。然而，这种转变被认为是一条单行道，因为自交受精限制了基因变异，从而阻止了进一步的进化。这个项目将决定主要是自花授粉的植物是否可以重新进化为异交。高度异交和主要自交的猴花物种将被比较它们的遗传变异，并人工选择决定自交率的花卉性状。该项目将让本科生参与进行独立实验和基因数据分析，并将为华盛顿州立大学的本科课程开发新的人工选择和基因进化实验室材料。以自交为主的群体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。虽然随着近亲交配，有效种群规模和重组的有效性预计会下降，但关于它们对适应性特征进化的影响的信息很少。在主要的自交谱系中，对异交性状再进化的限制表明，遗传变异是有限的，或者这种反应是可能的，但不太可能发生。为了增加花药-柱头距离这一关键异交性状，将对点滴草的异交群体和自交群体进行5个世代的人工选择，并确定实现的遗传力。对照品系和选择品系在实验前后的混合全基因组测序将揭示选择对它们基因组的比较效果。这种全基因组信息有可能将对适应的限制与自交受精的遗传后果(即低核苷酸多样性和强连锁不平衡)关键地联系起来。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.