Dissertation Research: Phylogeny of the Vittariaceae Ferns

研究生Edmund Crane在爱荷华州立大学乔纳森·温德尔和唐纳德·法勒的指导下，试图澄清热带蕨科葡萄科物种和属的分类界限，并推断这些类群之间的系统发育框架。系统发育研究将集中在这些蕨类植物的形态特征和叶绿体基因的DNA序列数据上。蕨类植物大多是热带附生植物，关于种内和种间DNA变异的研究很少。地理上的异常值包括奇怪的“阿巴拉契亚配子体”，它在美国东部广泛分布，但仅作为无性、克隆单倍体阶段或配子体被发现，在野外尚不为人所知的有性、二倍体孢子形成阶段。将分析来自代表广泛蕨类家族的样本的基因序列数据，以确定葡萄科在钩孢子目蕨类中的可能的系谱位置。然后，科间分析的结果将被用于评估葡萄科植物形态特征的可能来源。形态和分子数据集将被整合到解释这些植物的进化路径中。

Graduate student Edmund Crane, under the supervision of advisers Jonathan Wendel and Donald Farrar at Iowa State University, seeks to clarify the taxonomic delimitation of species and genera in the tropical fern family Vittariaceae and to infer a phylogenetic framework for the relationships among these taxa. The phylogenetic study will focus both on morphological features of these ferns and on DNA sequence data from chloroplast genes. The ferns are mostly tropical epiphytes, a group little studied with respect to DNA variation within and among species. Geographic outliers include the strange "Appalachian gametophyte," Vittaria appalachiana, which is widespread in the eastern U.S. but found solely as the asexual, clonal haploid stage or gametophyte and not known in the wild in the sexual, diploid spore-forming stage. Gene sequence data from samples representing a wide range of fern families will be analyzed to determine the likely genealogical position of the Vittariaceae among the leptosporangiate ferns. The results of the interfamily analysis will then be used to assess the likely derivation of morphological traits within the Vittariaceae. Both morphological and molecular datasets will be integrated in the interpretation of evolutionary pathways in these plants.