DISSERTATION RESEARCH: Evolutionary Genetics of Asexual Reproduction in a Wild Plant Species

尽管自然界普遍存在有性生殖，但在许多不同的生物中也发现无性生殖。无融合生殖（通过克隆种子进行无性生殖）发生在40个不同植物科的大约400个属中，并且总是与多倍体（全基因组复制）和杂交有关。迄今为止，这些混杂因素阻碍了对维持植物种群无融合性的进化和生态过程的研究。拟南芥属是拟南芥自交受精的野生近缘种，含有二倍体单性体。这提供了一个独特的机会来解开无融合和多倍体的潜在因素。本研究利用历史上为二倍体生物设计的种群遗传模型，探讨了Boechera野生种群性/无融合繁殖系统多态性的潜在过程。了解无融合和杂交之间的联系仍然是一个问题。无融合的适应度效应可能是由于杂交引起的，杂交给自交系的布氏蝇带来了遗传变异。通过杂交实验、实地研究和基因组测序技术的结合，pi将研究杂交和增加Boechera遗传多样性的适应度效应。本研究首次将这两个混杂因素从无融合性研究中完全分离出来。大多数作物都是杂交品种，引入无融合杂交有望通过它们的无性系后代固定优势系；因此，无融合生殖具有重要的农业意义。对自然界中这一繁殖系统的进化维持机制的深入了解，对于当前和未来在全世界抗击饥饿的努力至关重要。将对学生进行培训。

Despite the prevalence of sexual reproduction in nature, asexual reproduction is also found in many diverse organisms. Apomixis (asexual reproduction via clonal seed) occurs in approximately 400 genera across 40 different plant families, and is always associated with polyploidy (whole genome duplication) and hybridization. To date, these confounding factors have prevented investigation of the evolutionary and ecological processes maintaining apomixis in plant populations. The genus Boechera, a self-fertilizing wild relative of Arabidopsis thaliana, contains diploid apomicts. This offers a unique opportunity to disentangle the factors underlying apomixis and polyploidy. The proposed research examines the processes underlying a sexual/apomictic breeding system polymorphism in wild populations of Boechera, using population genetic models that historically are designed for diploid organisms. Understanding the link between apomixis and hybridization still remains problematic. Any putative fitness effects of apomixis may be due to hybridization, which introduces genetic variation to inbred Boechera. Through a combination of crossing experiments, field research, and genomic sequencing techniques, the PIs will investigate the fitness effects of hybridization and increased genetic diversity in Boechera. This research permits complete separation of these two confounding factors from the study of apomixis for the first time. Most crops are of hybrid origin, and the introduction of apomixis promises fixation of advantageous lineages through their clonal offspring; therefore, apomixis is of great agricultural interest. A developed understanding of the evolutionary maintenance of this breeding system in nature is critical to current and future efforts to battle hunger across the world. Training of students will occur.