Collaborative Research: The Evolution of Sex Ratio and Gender in Selfing vs. Outcrossing Clarkia spp. (Onagraceae)

开花植物进化出了多种确保授粉的机制。许多物种是“异型杂交”，依靠昆虫传递花粉，而其他物种是自花受精（每朵花都自己授粉）。从异种杂交的祖先进化到自花受精往往也有类似的结果。例如，与亲缘关系密切的自交物种相比，动物授粉的异交物种通常会开出更大的花朵，每朵花的花粉与胚珠的比例也更高。这项研究的问题是：自然选择是否如预期的那样在自交和异交物种之间产生更微妙的遗传差异？一些预测将会得到检验，其中包括异交者比自恋者更有可能在资源分配给男性和女性的功能上表现出反比关系。本文比较了三对亲缘关系较近的异交自交植物克拉克兰（Clarkia）雌雄生殖性状的遗传变异和遗传基础相关性。将进行温室和田间试验，以研究异交与自交的花性状独立进化的制约因素。10至12名本科生和1名博士后研究员将接受进化论、植物育种和繁殖、统计分析和结果展示方面的培训。这项研究将有助于我们理解自然选择影响与交配系统相关的进化变化的潜力和局限性。

Mazer9815300Flowering plants have evolved a variety of mechanisms that ensure pollination. Many species are "outcrossing", relying on insects to transfer pollen, while others are self-fertilized (each flower pollinates itself). The evolution of self-fertilization from outcrossing ancestors has often had similar outcomes. For example, animal-pollinated outcrossers often produce larger flowers and higher ratios of pollen to ovule production per flower than closely related self-fertilizing species. This study asks: Does natural selection operate as predicted to generate more subtle genetic differences between selfing and outcrossing species? Several predictions will be tested, including that outcrossers are more likely than selfers to exhibit an inverse relationship between the allocation of resources to male vs. female function. Three pairs of closely related outcrossing and self-fertilizing species in the wildflower genus Clarkia will be compared with respect to genetic variation in, and genetically based correlations among, male and female reproductive traits. Greenhouse and field experiments will be conducted to examine constraints on the independent evolution of floral traits in outcrossers vs. selfers.Ten to twelve undergraduate students and one post-doctoral researcher will receive training in evolutionary theory, plant breeding and reproduction, statistical analysis, and the presentation of results. This study will contribute to our understanding of both the potential and limits of natural selection to effect evolutionary changes associated with mating system.