Molecular Systematics and Morphology of the Adiantum Peruvianum Group (Pteridaceae)
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MIAMI UNIVERSITY The Graduate School Certificate for Approving the Dissertation We hereby approve the Dissertation of Mirabai R. McCarthy Candidate for the Degree: Doctor of Philosophy _____________________________________________________ Director (Dr. R. James Hickey) _____________________________________________________ Reader (Dr. Michael Vincent) _____________________________________________________ Reader (Dr. Richard Moore) _____________________________________________________ Reader (Dr. Martin Henry Stevens) ______________________________________________________ Graduate School Representative (Dr. Ellen Currano) ABSTRACT MOLECULAR SYSTEMATICS AND MORPHOLOGY OF THE ADIANTUM PERUVIANUM GROUP (PTERIDACEAE) by Mirabai R. McCarthy The nearly cosmopolitan Adiantum (Pteridaceae) comprises approximately 200 species, most of which are tropical in distribution. Adiantum ferns are predominantly terrestrial forest taxa, but some have adapted to living along stream banks or moist, rocky habitats. Historically, Adiantum has been divided into morphological species groups, as a means to help taxonomists categorize species and interpret inter-specific relationships within the genus. However, group concepts and circumscriptions have changed extensively over time, due in part to different interpretations about the relative importance of various morphological characters, and subsequently, alternate group names have been used in the literature. Currently there is no clear consensus on how species should be grouped. The present study utilizes molecular phylogenetics to delineate species groups within Adiantum, and traditional morphology to revise and circumscribe one species group, the A. peruvianum Group. Our phylogenetic analyses revealed four primary clades (A, B, C, and D) within Adiantum. Clades A & B contain temperate species, clade C contains primarily paleotropical species, and clade D contains neotropical species. Neotropical clade D contains two sub-clades D1 and D2. Clade D1 contains species with visible venuloid idioblasts present between veins, whereas clade D2 contains species lacking visible venuloid idioblasts between veins. The Adiantum peruvianum Group is a sub- clade (clade D2.III) within clade D2, and contains at least eight species: A. anceps, ‘A. ecuadorianum’, ‘A. exuberans’, A. mathewsianum, A. pectinatum, A. peruvianum, A. polyphyllum, and A. trapeziforme. Members of this group can be identified by having clathrate rhizome scales with minutely denticulate margins; segment stalks that stop abruptly at segment bases; discreet sori that are depressed-ovate, reniform, or occasionally lunate; ultimate segments that are dimidiate, trapeziforme, deltate, or occasionally ovate-falcate; free, dichotomous veins that end in marginal teeth; and laminar tissue that lacks visible idioblasts between veins. A taxonomic account, including descriptions and distributions of the species within this group is presented. Two members of this group, ‘Adiantum ecuadorianum’ and ‘A. exuberans’, are described as new, as is A. mariposatum, a member of clade D2.I. MOLECULAR SYSTEMATICS AND MORPHOLOGY OF THE ADIANTUM PERUVIANUM GROUP (PTERIDACEAE) A DISSERTATION Submitted to the Faculty of Miami University in partial Fulfillment of the requirements For the degree of Doctor of Philosophy Department of Botany by Mirabai R. McCarthy Miami University Oxford, OH 2012 Dissertation Director: R. James Hickey © Mirabai R. McCarthy 2012 TABLE OF CONTENTS Chapter 1. Introduction…………………………………………………………………..1 Chapter 2. The Adiantum peruvianum Group: a molecular circumscription……………8 Chapter 3. A taxonomic revision of the Adiantum peruvianum (Pteridaceae) Group…34 Chapter 4. Adiantum mariposatum (Pteridaceae, a new species from Ecuador………..83 Conclusion ……………………………………………………………………………..89 iii LIST OF TABLES Chapter 2. Table 2.1: Taxa, vouchers, localities and Genbank accession numbers for all sequences analyzed……………………………………………….24 Table 2.2: Primers used for PCR and sequencing in the present study……………27 Chapter 3. Table 3.1: A comparison of characters that can be used to differentiate members of the Adiantum peruvianum Group……………………..66 Table 3.2: Our two putative A. trapeziforme groups showing characters with means that are significantly different from each other………….68 iv LIST OF FIGURES Chapter 2. Figure 2.1: Consensus tree for 74 taxa, produced from analyses of rbcL dataset……………………………………………………………………..28 Figure 2.2: Consensus tree for 39 taxa, produced from analyses of combined atpA + rbcL datasets…………………………………………...……30 Figure 2.3: Phylogram resulting from combined atpA + rbcL reduced dataset, including only the A. peruvianum Group members……………...32 Chapter 3. Figure 3.1: Silhouettes of ultimate segments from species in the Adiantum peruvianum Group………………………………………….………69 Figure 3.2: Distribution maps of A. peruvianum, A. mathewsianum, A. anceps, A. polyphyllum…………………………………………………..….......70 Figure 3.3: Distribution maps of A. trapeziforme and A. exuberans………..…..…71 Figure 3.4: Scanning electron micrographs of spores…………………………..…72 Figure 3.5: Adiantum anceps………………………………………………………73 Figure 3.6: Adiantum ecuadorianum………………………………………..…..…74 Figure 3.7: Adiantum exuberans……………………………………………….…..75 Figure 3.8: Adiantum trapeziforme………………………………………………...76 Figure 3.9: Results from Principle Component Analyses…………………………77 Figure 3.10: Lectotype of Adiantum trapeziforme ………………………………...78 Figure 3.11: Adiantum mathewsianum………………………………………….…79 Figure 3.12: Adiantum pectinatum………………………………………………...80 Figure 3.13: Adiantum peruvianum…………………………………………….….81 Figure 3.14: Adiantum polyphyllum…………………………………………….…82 v Chapter 4. Figure 4.1: Holotype of Adiantum mariposatum………………..…………………87 Figure 4.2: Adiantum mariposatum adaxial & abaxial views of rachis and segment……………………………………………………………….88 vi ACKNOWLEDGEMENTS There are many folks to whom I owe thanks… Starting with my committee, I’d like to thank the current members: Drs. Jim Hickey, Mike Vincent, Rich Moore, Hank Stevens, Ellen Currano, and the historical members: John Kiss, John Rakovan, Hardy Eshbaugh, Beth Schussler, and Linda Watson. Each of you has impacted my life in a unique way, and I am incredibly grateful for the many years of mentoring, scholarly wisdom, and friendship. It has been such a joy to know and work with you all – thank you, thank you, thank you!!! Jim Hickey, I couldn’t imagine having a better advisor. I will always remember our friendly debates, and banter. You have carved out a very special place in my heart. I also thank Barb Wilson and Vickie Sandlin for taking such great care of so many details over the years – you are wonderful! Eric Tepe, I am incredibly grateful for your companionship in Ecuador, and your assistance with statistics. My lab mates and friends, Laura Klein, Sushma Shrestha, Steve & Jessica Rybzinski, Melanie Link-Perez, Susannah Fulton, Tia Alhquist, Jennifer Brown, Peter Pelser, Li Zheng, and Aaron Kennedy you helped Miami feel like home. Thank you all! I would also like to thank the Department of Botany at Miami University for funding much of my research through the Academic Challenge, and Willard Sherman Herbarium Grants; the following herbaria for specimen loans: AAU, F, GH, MO, MU, NY, US; Matt Duley, and Richard Edelman in the SEM facility; Johnny Kou for help with imaging scales and spores; the Center for Bioinformatics and Functional Genomics at MU; and the sequencing facility at Yale University. Finally, I am endlessly thankful to my mom, and my partner in life Jeremiah Jonaitis, for their encouragement, support, and especially for helping to keep me balanced throughout this process. I love you. vii 1 Introduction The primary objectives of this dissertation were to explore the evolutionary relatedness among species of Adiantum, and determine whether the A. peruvianum Group is monophyletic. A molecular phylogeny was produced as a hypothesis of evolutionary relatedness, and comparative morphological data were employed in the formalization of taxonomic descriptions and keys. Adiantum L. (Pteridaceae) The Pteridaceae is a large, diverse, and cosmopolitan family of leptosproangiate ferns of various ecological niches, including terrestrial, epiphytic, rupestral, and aquatic habitats. There are about 50 genera and over 1000 species in the Pteridaceae (Schuettpelz et al. 2007). Members of this family are characterized by sporangia born along veins, either superficially or along margins that are protected by a reflexed marginal flap (pseudoindusia), a vertical, interrupted annulus, trilete spores, and a chromosome number of x = 29 or 30 (Tryon & Tryon 1982). The Pteridaceae has experienced a great deal of scrutiny and debate about which genera should be included in this family and how they are related (Copeland 1947, Tryon & Tryon 1982, Tryon et al. 1990, Smith 1995, Prado et al. 2007, Schuettpelz et al. 2007). The most recent and robust molecular phylogenetic assessment of the Pteridaceae (Schuettpelz et al. 2007) divides the family into five monophyletic clades: the Pteridoid clade (17 genera, 400 species), Cryptogrammoid clade (3 genera, 23 species), Ceratopteridoid clade (2 genera, 6 species), Cheilanthoid clade (20 genera, 400 species), and Adiantoid clade (12 genera, 300 species). The latter Adiantoid clade includes the vittariod ferns (Adiantopsis, Anetium, Antrophyum, Haplopteris, Hecistopteris, Monogramma, Polytaenium, Radiovittaria, 1 Rheopteris, Vittaria) and Adiantum. A phylogenetic analysis of the Pteridaceae by Schuettpelz et al. (2007) found that the vittariod