DISSERTATION RESEARCH: What maintains species boundaries between interfertile, sympatric congeners? A test of prezygotic/postzygotic isolating mechanisms and cryptic hybridization

物种形成研究的一个关键目标是了解生殖障碍如何在不同的谱系中进化。 生殖隔离障碍预计将增加物种之间的分歧时间增加，并通过自然选择对生产不适合的杂交后代加强。 因此，共同出现在自然群落中的物种预计有很强的生殖隔离障碍，防止杂交。 尽管有这些预测，但许多具有弱生殖障碍的密切相关的植物物种在自然界中共存。 两个这样的物种是Collinsia linearis和C. rattanii在大部分分布区重叠，在同一时间开花，共享传粉者，在人工授粉实验中很容易杂交。 因此，拟议的研究使用这些物种作为模型，以更好地了解这些共存物种如何在物种之间潜在的基因流面前保持其独立的身份。 这项工作是对卡利什实验室目前正在进行的研究的补充，该实验室通过测试关于生殖障碍进化和交配系统进化的两个突出假设。 此外，该项目将有利于研究界使用Collinsia作为模型系统（北美的七个实验室），通过扩大对隔离障碍进化的理解，并提供跨物种生育力，生态学和Collinsia的地理学的广泛分析。

A critical goal of speciation research is to understand how reproductive barriers evolve among diverging lineages. Reproductive isolating barriers are predicted to increase with increasing divergence time among species and to be reinforced via natural selection against the production of unfit hybrid offspring. Thus, species that co-occur in natural communities are expected to have strong reproductive isolating barriers that prevent hybridization. Despite these predictions, many closely related plant species with weak reproductive barriers co-occur in nature. Two such species are Collinsia linearis and C. rattanii, which overlap in much of their range, flower at the same time, share pollinators, and readily hybridize in hand-pollination experiments. Thus, the proposed research uses these species as a model to better understand how such co-occurring species maintain their separate identities in the face of potential gene flow among the species. This work compliments research currently being conducted in the Kalisz lab by testing two prominent hypotheses on the evolution of reproductive barriers and mating system evolution. In addition, this project will benefit the research community using Collinsia as a model system (seven labs in North America), by expanding understanding of the evolution of isolating barriers and providing a broad-scale analysis of cross-species fertility, ecology, and biogeography in Collinsia.