Dissertation Research: Biogeography of the Conyzinae and theEvolution of Agamospermy

小行星9701347 研究生理查德·诺伊斯在印第安纳州大学的洛伦·里斯伯格教授的指导下，正在研究代表性的c。向日葵亚族Conyzinae的500种，包括飞蓬（Fleabanes）和小飞蓬（Conyza）。据推测，Conyzinae起源于南美洲并向北传播，但基于这些研究人员的初步DNA序列证据，Conyzinae似乎起源于Nopth美洲向日葵群，它们已经向南传播并传播到其他大陆，部分原因是杂草不受精就能播种（一种名为无受精的条件-蒲公英是更着名的例子）。额外的现场收集的样品，随后的核基因（核糖体ITS区）和叶绿体基因（ndhF）的分子测序和传统的形态特征的进一步研究，是任务，将导致系统发育重建的组。反过来，系谱框架有利于确定这些植物的地理迁移和进化轨迹，以及无受精条件的起源数量。 一个良好的支持fleabanes和他们的亲戚，美洲和非洲的系统发育，将改善组的分类，并提供可靠的标识标记。此外，研究可以在有利于无配子生殖起源的生态条件方面取得进展，无配子生殖是一种在大型向日葵家族的几个谱系中已知的独特的无性种子生产模式。

9701347 Rieseberg Graduate student Richard Noyes, under the direction of Prof. Loren Rieseberg at Indiana University, is studying the phylogenetic relationships of representatives of the c. 500 species of the sunflower subtribe Conyzinae, including Erigeron (fleabanes) and Conyza (horseweeds). Presumed to have originated in South America and spread northward, the Conyzinae appear instead to be a Nopth American group of sunflowers in origin, based on preliminary DNA sequence evidence from these researchers, which have spread southward and to other continents, in part as weeds that set seed without fertilization (a condition named agamospermy--dandelions being the better known example). Additional field collecting of samples, followed by molecular sequencing of a nuclear gene (ribosomal ITS regions) and a chloroplast gene (ndhF) and further study of traditional morphological characters, are tasks that will lead to phylogenetic reconstructions for the group. In turn, that genealogical framework facilitates the determination of geographical migrations and tracks in the evolution of these plants, and of the number of origins of the agamospermous condition. A well supported phylogeny of the fleabanes and their relatives, for the Americas and Africa, will improve classification of the group and provide reliable markers for identification. Also, studies can then progress on the ecological conditions favoring the origin of agamospermy, a peculiar asexual mode of seed production known in several lineages of the large sunflower family.