Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1995 A molecular phylogenetic study of the fern family Vittariaceae Edmund Hilton Crane III Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Botany Commons Recommended Citation Crane, Edmund Hilton III, "A molecular phylogenetic study of the fern family Vittariaceae " (1995). Retrospective Theses and Dissertations. 10894. https://lib.dr.iastate.edu/rtd/10894 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This mamiscr^t has been reproduced from ±e microfihn master. 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UMI 300 North Zeeb Road Ann Arbor, MI 48103 ii TABLE OF CONTENTS GENERAL INTRODUCTION I Dissertation Organization 1 CONVERGENT SIMPLIFICATION LEADS TO A POLYPHYLETIC VITTARIA 3 Abstract 3 Introduction 3 Materials and Methods 8 Results 14 Discussion 20 Acknowledgements 35 Literature Cited 36 A REVISED CIRCUMSCRIPTION OF THE GENERA OF THE FERN FAMILY VITTARIACEAE 40 Abstract 40 Introduction 40 Materials and Methods 41 Results and Discussion 43 Taxonomic Treatment 47 Acknowledgements 58 Literature Cited 59 SUPPORT FOR RECOGNITION OF RADIOVITTARIA MINIMA (VITTARIACEAE) 61 Abstract 61 Introduction 61 Materials and Methods 63 Results 63 Discussion 70 Acknowledgements 73 Literature Cited 74 GENERAL CONCLUSIONS 76 Phylogenetic Conclusions 76 Evolution of Morphological Characters 77 Taxonomic Conclusions 77 1 GENERAL INTRODUCTION The understanding of evolutionary relationships among organisms has advanced tremendously over the past 30 years. The combination of explicit techniques of character data analysis, use of computers to automate these techniques and the generation of genotypic character data using molecular methods made this revolution possible. Application of these methods to the study of plant phylogeny has been particularly effective because of the plasticity of plant morphology. This plasticity often makes the determination of homology of morphological characters uncertain. Pteridophytes are particularly amenable to molecular phylogenetic analysis because they lack the complex reproductive structures that seed plants share and upon which their phylogeny is based. This dissertation describes a molecular phylogenetic study of the fern family Vittariaceae. The species of the family are very simple morphologically and many of the limited morphological characters available for study in other groups of ferns are wanting in Vittariaceae. The analysis of gene sequence data from species representing the various genera of Vittariaceae produced a phylogenetic hypothesis for these taxa that suggests previously unsuspected relationships which are corroborated by morphological characters. A new classification of the genera of the family, based upon the molecular phylogeny, is proposed. In this classification, rank changes and new combinations are made with the purpose of maintaining monophyletic genera. Finally the rbcL sequence data are applied to a problem of interspecific relationship. Dissertation Organization The main body of this dissertation is organized into three chapters, which each consist of a journal article manuscript. The first chapter, "Convergent simplification leads to a polyphyletic Vittaria" is a paper submitted to the American Fern Journal. The second chapter, "Revised circumscription of the genera of the fern family Vittariaceae" will be submitted to the journal 2 Systematic Botany. The third chapter, "Support for recognition of Vittaria minima (Vittariaceae)", will be submitted to the American Journal of Botany. Following the third chapter is a chapter giving the general conclusions of the dissertation. The first paper is a general account of the results and conclusions of my Ph.D. project. It contains a literature review and description of methods that explains the background and procedures for all of the papers in this dissertation. An extensive discussion of the phylogenetic results and their implications for morphological character evolution is also included in the first paper. The second paper describes the taxonomic implications of the phylogenetic results and presents a formal proposal of changes in the circumscription of genera in the Vittariaceae. These changes in the genera are based upon the phylogenetic relationships shown in the molecular results. The third paper demonstrates the utility of rbcL data for resolving problems at the species level. Interspecific sequence divergence of rbcL is too low in angiosperms to be informative; however, sequence divergence among species of Vittariaceae often exceeds that seen among genera in angiosperm families. Sequence data is used to corroborate morphological differences seen between Vittaria remota and V. minima. The first and third papers have multiple authorship which reflects the following division of labor. Dr. Farrar supervised the selection of taxa for molecular study and contributed all of the new gametophyte data presented. Dr. Wendel supervised the generation and analysis of the molecular data. Mr. Crane generated and analyzed the new molecular data and made the observations of sporophyte morphology used for the revision. Together the three papers form a cohesive and inclusive account of the results of my Ph.D. project and are the molecular equivalent of a traditional morphological revision. 3 PHYLOGENY OF THE VITTARIACEAE; CONVERGENT SIMPLIFICATION LEADS TO A POLYPHYLETIC VITTARIA A paper in press in the American Fern Journal Edmund H. Crane, Donald R. Farrar, Jonathan F. Wendel ABSTRACT The fern family Vittariaceae contains nearly 100 species of tropical epiphytes with simple leaf morphology. Different interpretations of the limited number of morphological characters has led to controversy in the generic and subgeneric taxonomy of the family. A 1380 bp fragment of the chloroplast-encoded rbcL gene was amplified from DNA samples isolated from species representing the genera and subgenera of the family. Asymmetrical-PCR was used to produce single-stranded sequencing templates for each strand. Parsimony analysis of the sequence data resulted in two most parsimonious trees which differ only in the position of the monotypic Ananthacorus. Each tree has two main ciades which separate in a basal dichotomy. In the first principal clade, Ananthacorus appears either as sister to a clade containing Antrophyum ensiforme and A. boryanum or sister to a clade containing Vittaria lineata, V. gramimfolia, V. dimorpha, and V. isoetifolia. The other principal clade is made up primarily of species divided into two sister groups. One of these groups contains only Old-World species of Vittaria while the other contains New-World species of Vittaria corresponding to Benedict's subgenus Radiovittaria with Hecistopteris sister to the latter clade. The rbcL topology is congruent with the character-state distributions for several morphological characters; Spore shape, paraphysis terminal cell shape, gametophyte gemma development, and leaf arrangement on the rhizome. Introduction The fern family Vittariaceae contains approximately 100 species of tropical