Genetics of Adaptive Evolution in ZEA

9509074多布利亲缘关系密切的物种之间可能存在差异，因为它们的特征最好地适应了它们所居住的特定环境。这种适应性特征是如何在自然界中进化的，目前还不是很清楚。许多进化遗传学家同意这样的观点，即新适应的进化通常涉及许多基因的变化，每个基因对有机体的外观或表型都有很小的影响。其他人则认为，一两个影响很大的基因就足以建立新的适应，这是植物更常见的适应进化模式。与这场辩论密切相关的实证研究相对较少，也没有定论。这项拟议的研究将通过分析区分玉米属自然物种的适应性特征的遗传来研究适应性进化的遗传学。分析的性状将包括一年生和多年生的习性、根茎形成、开花日期、叶鞘中的色素沉着程度、种子重量以及花的大小和数量。这些性状的遗传将通过将控制这些性状的单个基因定位到它们在染色体上的位置来确定。通过这种方法，将有可能确定影响每个性状的基因的数量和单个基因的影响程度。总体而言，这项研究将提供一幅关于适应性重要性状的基因控制的详细图景，从中可以推断玉米适应性进化的遗传基础。由于玉米属包括栽培玉米，而且一些待研究的性状具有潜在的农学重要性，因此拟议的研究将有助于我们对玉米的理解和改进。

9509074 DOEBLEY Closely related species can differ from one another by traits that best adapt each to the specific environment that it inhabits. How such adaptive traits evolved in nature is not well-understood. Many evolutionary geneticists subscribe to the view that the evolution of new adaptations typically involves changes at many genes, each with a small effect on an organism's appearance, or phenotype. Others have argued that one or two genes of large effect are sufficient to establish a new adaptation and that this is the more common mode of adaptive evolution in plants. Empirical studies germane to this debate are relatively few and inconclusive. The proposed research will investigate the genetics of adaptive evolution by analyzing the inheritance of adaptive characters that distinguish natural species of the genus Zea. The traits analyzed will include annual vs. perennial habit, rhizome formation, flowering date, degree of pigmentation in the leaf sheath, seed weight, and flower size and number. The inheritance of these traits will be determined by mapping the individual genes that control these traits to their positions on the chromosomes. By this means, it will be possible to determine the number of genes affecting each trait and the magnitudes of the effects of the individual genes. Overall, this study will provide a detailed picture of the genetic control of adaptively important traits from which one can infer the genetic basis of adaptive evolution in Zea. Because the genus Zea includes cultivated corn and because some of the traits to be studied are of potential agronomic importance, the proposed research can contribute to our understanding and improvement of corn.