The interaction of selection, pleiotropy, and drift in phenotypic evolution

生物特征的进化最著名的是通过自然选择发生的，但也可以通过其他过程发生。性状可以通过遗传漂变而进化，尤其是在小种群中，当个体死亡或无法繁殖时，其原因可能与他们的适应性无关。性状也可以因多效性而进化，即单个基因影响多个性状。如果自然选择改变了一种性状，那么与之共享多效性基因的其他性状也会随之进化。虽然选择、漂变和多效性已经单独得到了很好的研究，但很少把这三者放在一起考虑。本研究将全面确定自然选择、漂移和多效性在植物物种中所起的作用，以显示最近跨纬度和海拔的进化变化模式。同时检查这些因素将有助于我们了解生物体如何适应或不适应环境变化。该项目将把选择的实地研究与实验室遗传学和基因组学结合起来。它将包括由K12教师和来自代表性不足群体的本科生组成的团队，提高他们对科学过程和科学职业的理解，并根据数据制作课堂课程材料。这个项目建立在几十年的实地和实验室研究与模式植物物种拟南芥。由于短雄蕊不利于种子的产生，近年来自花受精的进化削弱了雄蕊数量的自然选择。短雄蕊在这个物种的一些种群中已经消失，特别是在低海拔和纬度地区。已经确定了与雄蕊丢失相关的三个基因区域，允许在形态和基因组水平上同时研究进化。自然选择在雄蕊损失中的作用将通过已知基因型植物的田间和生长室内实验来评估。多效性的作用将通过雄蕊丧失和其他已知受选择影响的性状之间的统计关联，以及通过研究影响这些性状的基因区域的基因组关联来评估。最后，将通过研究全基因组多样性和评估小群体大小与雄蕊丢失之间的关系来评估漂变的作用。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Evolution of the traits of organisms most famously occurs through natural selection, but can also occur through other processes. Traits can evolve through genetic drift, especially in small populations, when individuals may die or fail to reproduce for reasons having nothing to do with their fitness. Traits can also evolve as a result of pleiotropy, in which single genes affect multiple traits. If natural selection acts to change one trait, other traits that share pleiotropic genes with it will also evolve. While selection, drift, and pleiotropy have been well-studied in isolation, rarely have the roles of all three been considered together. This research will comprehensively determine the roles of natural selection, drift, and pleiotropy in a plant species that shows patterns of recent evolutionary change across latitudes and altitudes. Examining these factors simultaneously will help us understand how organisms can adapt or fail to adapt to environmental change. The project will integrate field studies of selection with laboratory genetics and genomics. It will involve teams of K12 teachers and undergraduate students from underrepresented groups, improving their understanding of the process of science and scientific careers, as well as producing classroom curricular materials based on the data.This project builds upon decades of field and laboratory research with the model plant species Arabidopsis thaliana. The recent evolution of self-fertilization in this species has weakened natural selection on stamen number because short stamens do not contribute to seed production. Short stamens have been lost in some populations of this species, especially at low altitudes and latitudes. Three gene regions associated with stamen loss have been identified, permitting simultaneous investigation of evolution at the morphological and genomic levels. The role of natural selection in stamen loss will be evaluated using field and growth chamber experiments with plants of known genotypes. The role of pleiotropy will be evaluated by statistical associations between stamen loss and other traits known to be affected by selection, and by studying genomic associations for gene regions influencing these traits. Finally, the role of drift will be evaluated by studying whole-genome diversity and assessing the relationship between small population size and stamen loss.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.