Dissertation Research: Systematics of An Old Polyploid Complex in the Genus Gaudichaudia (Malpighiaceae)

在导师威廉安德森博士的指导下， 密歇根大学的研究生史蒂文杰瑟普 研究金虎尾科Gaudichaudia属植物 美洲热带的一个开花藤本植物科。 这一组中的物种表现出几种不同水平的 染色体加倍，称为多倍性，沿着几个 在形态学上， 分离的血统，导致不育和肥沃 中间体的 多倍体产生可育的能力 远亲谱系之间的杂交，以及多倍体 从不同的祖先杂交，然后回交， 亲本四倍体，导致遗传上复杂的 物种之间有明显的形态界限， 模糊不清 利用DNA限制性片段标记和蛋白质 电泳结合标准分类学方法， 研究人员将识别和描述物种， 从地理范围的角度分析生态种族， 土壤/气候分布。 使用计算机辅助方法， 系统发育分析，他们将推断起源， 进化历史的类群在这一属，并测试 该群体表现出多倍体循环模式的假说 通过杂交形成物种。 多倍体循环有 很少受到关注，特别是在热带木本植物中， 然而，高染色体数目的发生率表明， 热带分类群中的多倍体进化。 新的分子方法 在使用承诺突破我们的理解 多倍体进化的普遍性和意义。

With guidance from faculty adviser Dr. William Anderson, graduate student Steven Jessup of the University of Michigan is studying plants of the genus Gaudichaudia of the Malpighiaceae family, a group of flowering vines of the American tropics. Species in this group exhibit several different levels of chromosome doubling, called polyploidy, along with several apparent instances of hybridization between morphologically separate lineages, leading to both sterile and fertile intermediates. The ability of polyploids to produce fertile hybrids between distantly related lineages, and for polyploid hybrids from different progenitors to cross and then backcross to parental tetraploids, results in a genetically complex array of forms where clear morphological boundaries between species are blurred. By using DNA restriction fragment markers and protein electrophoresis in combination with standard taxonomic methods, the researchers will identify and characterize species, and analyze ecological races in terms of geographic range and soil/climate distributions. Using computer-aided methods of phylogenetic analysis, they will infer the origins and evolutionary history of taxa in this genus, and test the hypothesis that the group exhibits a pattern of polyploid cycles of speciation through hybridization. Polyploid cycles have received little attention, especially in tropical woody plants, yet the incidence of high chromosome numbers suggests extensive polyploid evolution in tropical taxa. The new molecular methods in use promise a breakthrough in our understanding of the prevalence and significance of polyploid evolution.