University of Kentucky UKnowledge Theses and Dissertations--Biology Biology 2012 ECOLOGY OF MATING PATTERNS AND SEXUAL SELECTION IN DICKCISSELS BREEDING IN MANAGED PRAIRIE Bridget Frances Sousa University of Kentucky, [email protected] Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Sousa, Bridget Frances, "ECOLOGY OF MATING PATTERNS AND SEXUAL SELECTION IN DICKCISSELS BREEDING IN MANAGED PRAIRIE" (2012). Theses and Dissertations--Biology. 17. https://uknowledge.uky.edu/biology_etds/17 This Doctoral Dissertation is brought to you for free and open access by the Biology at UKnowledge. It has been accepted for inclusion in Theses and Dissertations--Biology by an authorized administrator of UKnowledge. For more information, please contact [email protected]. STUDENT AGREEMENT: I represent that my thesis or dissertation and abstract are my original work. Proper attribution has been given to all outside sources. 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REVIEW, APPROVAL AND ACCEPTANCE The document mentioned above has been reviewed and accepted by the student’s advisor, on behalf of the advisory committee, and by the Director of Graduate Studies (DGS), on behalf of the program; we verify that this is the final, approved version of the student’s thesis including all changes required by the advisory committee. The undersigned agree to abide by the statements above. Bridget Frances Sousa, Student Dr. David Westneat, Major Professor Dr. Brian Rymond, Director of Graduate Studies ECOLOGY OF MATING PATTERNS AND SEXUAL SELECTION IN DICKCISSELS BREEDING IN MANAGED PRAIRIE DISSERTATION A dissertation submitted in partial fulfillment of the requirements for the Doctor of Philosophy in the College of Arts & Sciences at the University of Kentucky By Bridget Frances Sousa Lexington, Kentucky Director: Dr. David F. Westneat, Professor of Biological Sciences Lexington, Kentucky 2012 copyright © Bridget Frances Sousa 2012 ABSTRACT OF DISSERTATION ECOLOGY OF MATING PATTERNS AND SEXUAL SELECTION IN DICKCISSELS BREEDING IN MANAGED PRAIRIE Males of many species have elaborate phenotypes that are absent in females and that are thought to be the result of sexual selection. Sexual selection requires: (i) variance in male mating success, (ii) variation in male phenotype, and (iii) covariation between male mating success and male phenotype. Environmental conditions influence these factors, and management practices that alter environmental conditions have the potential to shape mating patterns and sexual selection. I investigated the hypothesis that the frequency of fire, used to manage tallgrass prairie, affects the mating patterns and process of sexual selection in the organisms breeding in managed prairies. I studied dickcissels (Spiza americana), a small songbird resident in tallgrass prairie. I first examined mating patterns and sexual selection in dickcissels independent of burning regime. I found variation among males in the number of mates attracted, in the number of offspring sired with each mate, and the offspring sired with the mates of other males. I found a positive association between social mates and siring success, but no evidence for an effect of breeding density or synchronous nesting on mating success. Male dimorphic traits, size, song, and plumage, showed between-individual variation but selection gradients were weak and often fluctuated between the years of study. I next examined patterns of mating success in plots burned on a variable schedule. I found little evidence that burning influenced either the mean or the variance in social mating success, paternity, or male phenotype. Burning regime also had no influence on sexual selection gradients with the single exception of selection on tarsus length. Temporal variation was more important for patterns of mating success and sexual selection gradients on male traits than was burning regime. The demography of dickcissels in the breeding season suggests, however, that habitat management on a larger scale may be more influential. My findings extend our understanding of sexual selection in birds and the effects of management on the factors required for sexual selection and the magnitude of selection. KEYWORDS: sexual selection, grassland management, mating patterns, dickcissel, tallgrass prairie Bridget F. Sousa Student Signature Date ECOLOGY OF MATING PATTERNS AND SEXUAL SELECTION IN DICKCISSELS BREEDING IN MANAGED PRAIRIE By Bridget Frances Sousa David Westneat Director of Dissertation Brian Rymond Director of Graduate Studies This dissertation is dedicated to my mother. You were right, that was a good research idea ACKNOWLEDGEMENTS This dissertation is dedicated to my mother, Dr. Sheila Byrne Sousa, whose response to my every childhood question was, “That sounds like a great research project.” She has offered her encouragement and support throughout, sacrificing several months of vacation over the years to assist me as field technician and secretary. I am forever grateful for her many years of technical, field, financial and grammatical support. My father has also provided love and support throughout my education. I would also like to extend my profound thanks to my brother, Dr. Duncan Sousa, and my dear friend, Lauren Reynolds. They picked me up when I was down, were a constant source of encouragement and perspective, and even assisted me in the field despite a total lack of any reasonable form of compensation. Dr. David Westneat has been an understanding and insightful advisor. He has helped me develop as a professional and provided valuable guidance in the analysis of non significant data. I have benefited immensely from his expertise and mentoring. Dave’s rock star popularity has led a number of students through his doors. My lab mates have been a constant source of support. We have read each others’ manuscripts, learned from each other and taught each other so much more than statistics and lab techniques. My thanks go out to Sarah Martin Stewart, Dr. Ian Stewart, Dan Wetzel, Kate “Utah” Newman, Dr. Amanda Ensminger, Patricia Hartman, Sanh Kin Diep and Damon Orsetti. I would also like to thank my committee and outside examiner for their helpful suggestions. Dr. Nicholas McLetchie, Dr. Phil Crowley, Dr. Charles Fox and Dr. John Cox have all been very supportive. iii Many people at the Museum of Vertebrate Zoology guided me through my years as an undergraduate. Their aid continued into my graduate career. Thanks to Dr. Eileen Lacey and Dr. Jim Patton for inspiration, education and the invitation to conduct my lab work at the MVZ. No research endeavor can be accomplished without the mostly invisible army that supports it. I also owe a great deal of thanks to the staff of the Biology Department, particularly Beverly Taulbee, Melissa Justice, Cheryl Edwards, Kelley Salyers and Mike Adams. Missy and Bev have been especially helpful throughout my graduate career and I appreciate their time and efforts. I am also indebted to the faculty and staff at Konza Prairie Biological Station, especially Dr. Brett Sandercock, Barb van Slyke and Tom van Slyke. A number of undergraduates also spent countless hours enduring blood sucking insects, vicious dickcissels, fire, flood and the occasional golf ball sized hail storm. Thank you Wayne Li, Lauren Scopel, Daily Leonhard and Ryan Sheldon for all your hard work and dedication. Finally, I would like to acknowledge Konza Prairie Biological Station, which is a preserve of The Nature Conservancy managed by the Division of Biology at Kansas State University, and the following sources of funding: the Gertrude Flora Ribble Fund, the Department of Biology, the UK Graduate School, the Animal Behavior Society, and the American Philosophical Society’s Lewis and Clark Fund for Field Research. iv TABLE OF CONTENTS Acknowledgements............................................................................................................ iii List of Tables .................................................................................................................... vii List of Figures.................................................................................................................... ix Chapter One: Introduction ..................................................................................................1 Chapter Two: Sickly singers: a review of song and parasite mediated sexual selection Hypotheses of parasite mediated sexual selection.........................................................7 Avian song characteristics ...........................................................................................13