The Role of Mating System Divergence in Plant Speciation

了解新物种的形成，物种形成的过程，是进化生物学中最具挑战性的问题之一。不同开花植物的物种形成率差异很大，并且与通过自花受精而不是与其他个体交配的繁殖程度密切相关(称为植物‘交配系统’)。该项目整合了新的进化理论、田间和实验室实验以及基因组分析，以检验有关交配系统变化在植物物种形成中的作用的关键假设。该项目调查了决定何时何地发生强烈交配障碍的过程。它将阐明自交受精率的进化变化是否直接促进了不同物种之间的生殖隔离。实验工作集中在加州一年生植物Clarkia xantiana的两个亚种上，这两个亚种的交配系统不同。一个亚种主要是自花授粉，另一个亚种主要是异交。这些植物是研究的理想植物，因为它们展示了新形成的物种的特征。然而，它们只是在最近才出现分歧，仍然可以进行杂交。此外，它们的花朵在它们共同出现的地方有很大的不同，这是物种形成过程的一个标志。这项拟议的工作还将通过一个名为“市场科学”的创新项目向公众广泛宣传，在这个项目中，研究人员向当地农贸市场的公众介绍主题，并与公众直接接触。这一非常成功的计划将扩大到包括进化生物学的新主题。拟议的项目还将直接让本科生参与课堂上的真实研究。拟议的工作涉及三个主要目标。目的1研究自然选择在姐妹异交和自交世系生殖性状置换进化中的作用。这项工作涉及到在交配系统中包含发散的字符移位的新的理论模型的发展。它还包括大规模的野外实验，量化个体特征在生殖隔离中的作用，并确定它们的遗传基础。目的2研究姐妹异交和自交世系之间形成杂种的生态和遗传成本。这项工作包括田间实验和基因组分析，以量化杂交后代的繁殖适合度。目标3通过询问生殖隔离机制如何共同影响两个分类群之间的变异和导入的全基因组模式来合成目标1和目标2。这项综合性工作将通过唤起人们对交配系统对自然界中广泛物种形成的潜在影响的关注来推动进化研究。该奖项反映了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 formation of new species, the process of speciation, is among the most challenging problems in evolutionary biology. Rates of speciation vary widely among flowering plants and are strongly associated with the degree of reproduction via self-fertilization versus mating with other individuals (known as the plant 'mating system'). This project integrates new evolutionary theory, field and laboratory experiments, and genomic analyses to test key hypotheses about the role of mating system changes in plant speciation. The project investigates the processes that determine where and when strong barriers to mating occur. It will clarify whether evolutionary changes in rates of self-fertilization directly promote reproductive isolation between diverging species. The experimental work focuses on two subspecies of the California annual plant, Clarkia xantiana, which differ in mating system. One subspecies is primarily self-fertilizing the other is primarily outcrossing. These plants are ideal for study because they exhibit features of newly formed species. However, they have only recently diverged and can still interbreed. Moreover, their flowers are substantially different where they co-occur, a signature of the speciation process. The proposed work will also involve extensive outreach to the public via an innovative program called, 'Market Science', where researchers present topics to and engage directly with the public at local farmers' markets. This highly successful program will be expanded to include new topics on evolutionary biology. The proposed project will also directly involve undergraduates in authentic research in the classroom.The proposed work address three primary objectives. Aim 1 examines the role of natural selection in the evolution of reproductive character displacement between sister outcrossing and selfing lineages. This work involves the development of novel theoretical models of character displacement that incorporate divergence in mating system. It also involves large-scale field experiments that quantify the role of individual traits in conferring reproductive isolation and determine their genetic basis. Aim 2 examines the ecological and genetic costs of hybrid formation between sister outcrossing and selfing lineages. This work involves field experiments and genomic analyses that quantify the reproductive fitness of hybrids. Aim 3 synthesizes Aims 1 and 2 by asking about how reproductive isolating mechanisms collectively influence genome-wide patterns of variation and introgression between the two taxa. This integrative work will advance evolutionary research by calling attention to the potential for mating system to influence speciation broadly in nature.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.