Dissertation Research: Barriers to Genetic Exchange Between Two Species of Mimulus

本研究将确定生殖隔离进化、维持和增强的机制和过程。摘要以拟南花（Mimulus guttatus）和拟南花（M. nasutus）两种自然杂交的野花为研究对象，研究了其生殖隔离的模式系统。这种性质的研究对于确定密切相关的分类群之间基因流动的原因和结果非常重要，因此对理解物种形成的早期过程至关重要。迄今为止，在这两个物种中已经确定了主要的生殖隔离机制：开花物候的差异，M. nasutus主要的自交交配系统，以及花粉不育形式的杂交破坏的初步证据。本研究将在一个共同的花园环境中确定杂种相对于两个亲本种的适合度。其中一个实验将把杂交生物和亲本生物放在一个自然发生的杂交区，并测量相对于亲本的杂交个体的适应性、物候重叠和自交率。这个实验将检验生殖隔离的本质，并预测这种隔离对基因流动的影响。

This research will determine the mechanisms and processes underlying the evolution, maintenance, and enhancement of reproductive isolation. Mimulus guttatus and M. nasutus (Scrophulariaceae) two naturally hybridizing species of wildflowers, are used as a model system for studying reproductive isolation. Studies of this nature are important in determining the causes and consequences for gene flow between closely related taxa, and are therefore ultimately important in understanding early processes of speciation. To date, major reproductive isolating mechanisms have been identified in these two species: differences in flowering phenology, a predominantly selfing mating system of M. nasutus, and preliminary evidence of hybrid breakdown in the form of pollen inviability. This study will determine the fitness of hybrids relative to both parent species in a common garden setting. One experiment will place hybrid and parental organisms in a naturally occurring hybrid zone, and measure fitness, phenological overlap, and selfing rates for hybrid individuals relative to the parentals. This experiment will allow examination of the nature of reproductive isolation, and prediction of the consequences to gene flow this breakdown causes.