Genetics of Adaptive Evolution in ZEA

小行星9509074 密切相关的物种可以通过最好地适应其栖息的特定环境的特征而彼此不同。 这种适应性特征在自然界中是如何进化的，目前还没有很好的理解。 许多进化遗传学家赞同这样的观点，即新适应的进化通常涉及许多基因的变化，每个基因对生物体的外观或表型都有很小的影响。 另一些人则认为，一个或两个影响大的基因足以建立一种新的适应，这是植物适应性进化的更常见模式。 与这一争论密切相关的实证研究相对较少，而且没有结论。 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与多年生习性、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，这项研究将提供一个详细的图片的适应性重要性状的遗传控制，从中可以推断出适应性进化的遗传基础在玉米。 由于玉米属包括栽培玉米，并且由于要研究的一些性状具有潜在的农学重要性，因此拟议的研究有助于我们了解和改进玉米。

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.