UNLV Retrospective Theses & Dissertations 1-1-2007 Seed fates of Arctomecon californica Laura Megill University of Nevada, Las Vegas Follow this and additional works at: https://digitalscholarship.unlv.edu/rtds Repository Citation Megill, Laura, "Seed fates of Arctomecon californica" (2007). UNLV Retrospective Theses & Dissertations. 2129. http://dx.doi.org/10.25669/yge6-mkht This Thesis is protected by copyright and/or related rights. It has been brought to you by Digital Scholarship@UNLV with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Thesis has been accepted for inclusion in UNLV Retrospective Theses & Dissertations by an authorized administrator of Digital Scholarship@UNLV. For more information, please contact [email protected]. SEED FATES OF ARCTOMECON CALIFORNICA by Laura Megill Bachelor of Arts University of Colorado, Colorado Springs 2001 Master of Science University of Nevada, Las Vegas 2007 A thesis submitted in partial fulfillment of the requirements for Master of Science Degree in Biological Science School of Life Sciences College of Sciences Graduate College University of Nevada, Las Vegas May 2007 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. UMI Number: 1443777 INFORMATION TO USERS The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleed-through, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. UMI UMI Microform 1443777 Copyright 2007 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Thesis Approval uNiy The Graduate College University of Nevada, Las Vegas 26 February ,20 07 The Thesis prepared by Laura Megill Entitled Seed Fates of Arctomecon californica (Papaveraceae) is approved in partial fulfillment of the requirements for the degree of Master of Science Degree, School of Life Sciences C. Examination Committee Chair 'V— bOean of the Graduate College Examination Committee Member Examination CommiiteeiMemher zxamination Committee Member Graduate College mculty Representative 11 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ABSTRACT Seed Fates oi Arctomecon californica by Laura Megill Dr. Lawrence R. Walker, Examination Committee Chair Professor of Life Sciences University of Nevada, Las Vegas Seed fates were investigated for Arctomecon californica a Critically Endangered plant in the State of Nevada. This species is a short-lived rare perennial plant endemic to the Mojave Desert. Conservation plans for the species would benefit by understanding the fate of A. californica seeds from seed production, dispersal, and granivory to incorporation within the seed bank. Each year, 18% of the capsules suffered predispersal loss. The average number of seeds per capsule ranged from 87 to 99 seeds. Seed viability ranged from 87.5% to 100% per plant. Seed production was highly dependent on the number of mature capsules per plant and was used to predict seed output per plant. Dispersal from the capsule mainly by the ejection of seeds triggered by wind tended to disperse seeds away from parent plants. Once seeds reached the soil surface, ants were the main agents responsible for seed removal. The role of rodents appeared to be minimal in A. californica seed removal experiments. Examination of the potential role of seed elaiosomes in dispersal elicited variable responses from ants. The seed bank of this species was spatially heterogeneous with most seeds found either close to the surface (34%) or deep within the soil column (26%). The proportion of viable seeds tended to be highest within the 6-15 cm depth increment, suggesting the presence of a long-lived seed bank. The distribution of seeds within the seed bank with respect to viability indicated 111 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. 10.5% were viable seeds while 35.6% consisted of seed fragments or decayed seeds and the rest, 53.9% were filled but non-viable seeds. IV Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. TABLE OF CONTENTS ABSTRACT................................................................................................................................. iii ACKNOWLEDGMENTS..........................................................................................................vi CHAPTER 1 INTRODUCTION...........................................................................................1 CHAPTER 2 METHODS.......................................................................................................7 Study Sites ...............................................................................................................................7 Seed Production ......................................................................................................................8 Seed Dispersal ......................................................................................................................... 8 Granivory ...............................................................................................................................10 Elaiosome...............................................................................................................................10 Seed B ank ..............................................................................................................................12 Seed Fate Model ................................................................................................................... 13 Statistical Analyses ...............................................................................................................14 CHAPTER 3 RESULTS.......................................................................................................17 Seed Production ....................................................................................................................17 Seed Dispersal .......................................................................................................................21 Granivory ...............................................................................................................................24 Elaiosome...............................................................................................................................25 Seed B ank ............................................................................................................................. 28 Seed Fate Model ...................................................................................................................29 CHAPTER 4 DISCUSSION................................................................................................ 31 Seed Production .....................................................................................................................31 Seed Dispersal ........................................................................................................................34 Granivory ................................................................................................................................38 Elaiosome................................................................................................................................40 Seed B ank .............................................................................................................................. 43 Seed Fate M odel....................................................................................................................47 Management Recommendations ......................................................................................... 48 APPENDIX I FIGURES........................................................................................................51 APPENDIX II TABLES..........................................................................................................75 BIBLIOGRAPHY.......................................................................................................................85 VITA........................................... 93 Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. ACKNOWLEDGMENTS I would like to thank the many people who made this thesis possible. It is difficult to overstate my gratitude to my MS advisor and committee chair, Dr. Lawrence Walker. With his enthusiasm, his inspiration, his great efforts to explain things clearly and simply, and his grasp for theoretical