Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-2009 Speciation, Species Concepts, and Biogeography Illustrated by a Buckwheat Complex (Eriogonum corymbosum) Mark W. Ellis Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Biology Commons Recommended Citation Ellis, Mark W., "Speciation, Species Concepts, and Biogeography Illustrated by a Buckwheat Complex (Eriogonum corymbosum)" (2009). All Graduate Theses and Dissertations. 370. https://digitalcommons.usu.edu/etd/370 This Dissertation is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. i SPECIATION, SPECIES CONCEPTS, AND BIOGEOGRAPHY ILLUSTRATED BY A BUCKWHEAT COMPLEX (ERIOGONUM CORYMBOSUM) by Mark W. Ellis A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Biology Approved: ________________________ ________________________ Dr. Paul G. Wolf Dr. Karen E. Mock Major Professor Committee Member ________________________ ________________________ Dr. Michael E. Pfrender Dr. Leila Shultz Committee Member Committee Member ________________________ ________________________ Dr. Carol D. von Dohlen Dr. Byron R. Burnham Committee Member Dean of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2009 ii Copyright © Mark W. Ellis, 2009 All Rights Reserved iii ABSTRACT Speciation, Species Concepts, and Biogeography Illustrated by a Buckwheat Complex (Eriogonum corymbosum) by Mark W. Ellis, Doctor of Philosophy Utah State University, 2009 Major Professor: Dr. Paul G. Wolf Department: Biology The focus of this research project is the complex of infraspecific taxa that make up the crisp-leaf buckwheat species Eriogonum corymbosum (Polygonaceae), which is distributed widely across southwestern North America. This complex provides an ideal taxonomic group for research into population relationships and speciation. To avoid unnecessary debates about taxonomic validity or contentious issues regarding appropriate species definitions, the historical evolution of the species concept is first reviewed in detail, demythologizing an often-assumed species problem. Following that review, the E. corymbosum complex is examined specifically. Although eight varieties of E. corymbosum are currently recognized based on morphological characters, this group of large, woody shrubs has a history of revisions that demonstrates the uncertainty inherent in circumscriptions based on morphology iv alone. The apparent rarity of some E. corymbosum varieties also presents conservation and management challenges, demonstrating the need for taxonomic verification. To bring greater resolution to this group, I genetically tested samples from populations of six of the eight varieties of E. corymbosum, as well as a number of related buckwheat species. With 103 AFLP loci and chloroplast sequence data from 397 samples, I found strong support for the designation of the recently named E. corymbosum var. nilesii. This predominantly yellow-flowered variety had previously been considered part of a more common variety, and thus its management had not been of particular concern. But as a separate variety, its known distribution is quite limited, and management for this rare plant is now advised. An examination of the biogeography of the E. corymbosum complex provides further support for the apparent rarity of var. nilesii, as well as var. aureum. Both taxa are found at the periphery of the complex, and both may represent insipient species. While all other varieties appear more closely related to each other than to varieties aureum and nilesii, with overlapping ranges confined mostly to the Colorado Plateau, both var. aureum and var. nilesii appear to have allopatric ranges largely off the Colorado Plateau. It appears these two peripheral varieties may each entail a separate center of origin for two new taxa. (185 pages) v ACKNOWLEDGMENTS I cannot say enough about those who helped me with this project and this period in my life, so this section will be paltry indeed. Paul Wolf was a superb advisor, providing direction, information, creative ideas, and a sense of optimism I sorely needed. He was and is far more than an advisor. He and Carol Rowe were also friends and family, giving me a sense of balance that made this accomplishment possible. I am very grateful for the support of my committee members Carol von Dohlen, Mike Pfrender, Karen Mock, and Leila Shultz. Their combined knowledge is rather frightening, and their ideas, critiques, and positive support were greatly appreciated. Although I should have drawn from that well far more often than I did, I will again in the future. I was very fortunate to get financial support from the US Fish and Wildlife Service and from the Margaret Williams Research Grant of the Nevada Native Plant Society. Numerous Native Plant Society members, biologists, and plant enthusiasts also helped me select sample sites, including Gina Glenne, John Anderson, and Jerry Tiehm. Thanks to Dr. James Reveal for advice and some voucher identifications. There has also been a truckload of people here at Utah State University who were generous with their time, experience, intelligence, outrageous senses of humor, exceptional tolerance, and unhesitating support. A few of those good souls include Mary Barkworth, Lee Bjerregaard, Carrie Drake, Eric Pilgrim, Usha Menon, Michael Piep, Alice Lindahl, Lin Johnson, Mark Miller, Colin Brammer, Jessie Roper, Rochelle Gainer, Phil Tuckett, Kellon Hansen, Ashwin Kumar, Ninglin Yin, Chris Feldman, Annie Jensen, vi Andrea Bell, Chris Gerrard, Josh Der, Kristal Waltrous, Aaron Duffy, Jake Davidson, Tiffany Sorrentino, and Jeran Stratford. Finally, I dedicate this dissertation to Reiko Hayashi for giving me far more support than I deserved. Mark W. Ellis vii CONTENTS Page ABSTRACT.......................................................................................................................iii ACKNOWLEDGMENTS .................................................................................................. v LIST OF TABLES.............................................................................................................. x LIST OF FIGURES ........................................................................................................... xi CHAPTER 1. INTRODUCTION ......................................................................................... 1 Literature Cited ............................................................................... 4 2. THE MYTH OF THE SPECIES PROBLEM ............................................... 6 Introduction..................................................................................... 6 The species problem from past to present........................... 8 What is everyone talking about?....................................... 10 The multiple meanings of "species" ................................. 11 A western perspective....................................................... 13 The Early Development of Species Concepts............................... 14 The Ionians........................................................................ 15 The Pythagoreans.............................................................. 18 The Socratics..................................................................... 22 Non-Socratic views........................................................... 29 The early Common Era..................................................... 32 Augustine of Hippo........................................................... 33 The collapse of the Roman Empire................................... 34 The Species Concept During the Middle Ages............................. 36 Thomas Aquinas and the new synthesis ........................... 40 Emergence from the Middle Ages and the Development of Natural Theology................................................................... 44 From Darwin to the Present .......................................................... 54 viii Species concepts and the Modern Synthesis..................... 59 Classes versus individuals................................................. 66 Why are there competing species concepts?..................... 71 Textbooks continue the myth rather than offer ontological clarity......................................................................... 73 Recap and Conclusion................................................................... 77 Literature Cited ............................................................................. 79 3. THE TAXONOMIC DESIGNATION OF ERIOGONUM CORYMBOSUM VAR. NILESII (POLYGONACEAE) IS SUPPORTED BY AFLP AND CPDNA ANALYSES................................................................................... 88 Abstract......................................................................................... 88 Introduction................................................................................... 88 Materials and Methods.................................................................. 92 Collections ........................................................................ 92 DNA extraction................................................................. 94 Amplified Fragment Length Polymorphisms ................... 94