Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-2011 Quantitative Genetic Analysis of Reproduction Traits in Ball Pythons Benson H. Morrill Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Animal Sciences Commons Recommended Citation Morrill, Benson H., "Quantitative Genetic Analysis of Reproduction Traits in Ball Pythons" (2011). All Graduate Theses and Dissertations. 1005. https://digitalcommons.usu.edu/etd/1005 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]. QUANTITATIVE GENETIC ANALYSIS OF REPRODUCTION TRAITS IN BALL PYTHONS by Benson H. Morrill A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY in Animal Science Approved: ______________________________ ______________________________ Lee F. Rickords Thomas D. Bunch Major Professor Committee Member ______________________________ ______________________________ Christopher J. Davies Justin G. Julander Committee Member Committee Member ______________________________ ______________________________ Susannah S. French Kenneth L. White Committee Member ADVS Department Head ______________________________ Mark R. McLellan Vice President for Research and Dean of the School of Graduate Studies UTAH STATE UNIVERSITY Logan, Utah 2011 ii Copyright © 2011 All Rights Reserved iii ABSTRACT Quantitative Genetic Analysis of Reproduction Traits in Ball Pythons by Benson Howard Morrill, Doctor of Philosophy Utah State University, 2011 Major Professor: Dr. Lee F. Rickords Department: Animal, Dairy and Veterinary Sciences Although the captive reproduction of non-avian reptiles has increased steadily since the 1970’s, a dearth of information exists on successful management practices for large captive populations of these species. The data reported here come from a captive population of ball pythons ( Python regius ) maintained by a commercial breeding company, The Snake Keeper, Inc. (Spanish Fork, UT). Reproductive data are available for 6,480 eggs from 937 ball python clutches. The data presented suggest that proper management practices should include the use of palpation and/or ultrasound to ensure breeding occurs during the proper time of the female reproductive cycle, and that maintenance of proper humidity during the incubation of eggs is vitally important. Ball python reproduction traits (clutch size, clutch mass, relative clutch mass, egg mass, hatch rate, egg length, egg width, hatchling mass, healthy offspring per clutch, week laid, and days of incubation) were recorded for the clutches laid during this study. For the 937 clutches, the identity of the dam and sire were known for 862 (92%) and 777 iv (83%) of the clutches, respectively. A multivariate model that included nine of the 11 traits listed above was compiled. Heritability and genetic and phenotypic correlations were calculated from the multivariate analysis. The trait that showed the most promise for use in artificial selection to increase reproduction rates was clutch size due to considerable genetic variation, high heritability, and favorable genetic correlations with other reproduction traits. Although large datasets have been published for twinning in avian species, relatively few are available for non-avian reptiles. Reported here are 14 sets of twins produced from 6,480 eggs from 937 ball python clutches. The survival rate for twins during the first 3 months of life in our study was 97%. Interestingly, 11 of the sets of twins were identical in sex and phenotype, and additional genetic data suggested the rate of monozygotic twinning within this captive population of ball pythons was higher than that of dizygotic twinning. Further, using microsatellite analysis we were able to generate data that shows three sets of python twins were genetically identical. (143 pages) v ACKNOWLEDGMENTS I would like to thank my major professor, Dr. Lee Rickords, and my committee members, Dr. Thomas Bunch, Dr. Chris Davies, Dr. Justin Julander, and Dr. Susannah French, for the mentoring and support they provided for me during this process. I would also like to thank Dan and Colette Sutherland of The Snake Keeper, Inc. for their willingness to work with me to gather and prepare the data presented in this work. Well- deserved thanks also go to Dr. Joseph Mendelson, Dr. Michael Pfrender, Dr. Daniel Mulcahy, and Dr. Chris Feldman for the time they spent with me as a high school and undergraduate student to help me attain my first successful experiences in academic research. Marcy Labrum, Kimberly Blanchard, and Davin Larsen provided me with many helpful suggestions during the writing of this dissertation, and frequently gave me friendly support in the form of listening ears when I was confronted with challenges. I would also like to collectively thank Dr. Clay Isom and the students in his lab along with the students in Dr. Davies’ and Dr. White’s labs for their support and friendship. My parents, Howard and Evelynda Morrill, always encouraged me to pursue any interests I had, even if they were associated with creepy-crawly animals. I greatly appreciate their love and encouragement over the years, and for allowing me to keep many rodents and reptiles in their home. My wife’s parents, Daniel and Diana Atkins, have also provided significant love and support to me during the completion of this degree and I have appreciated their thoughts and suggestions during this process. Numerous other family members and friends significantly contributed to my success by helping my wife and children be safe and taken care of during all the time I spent in the lab and writing. vi Perhaps most importantly, I would like to thank my wife, Sarah, for her love and patience through all the long nights and weekends that were sacrificed for me to complete this manuscript. I could not have finished this work without her constant encouragement and support. Lastly, I would like to thank my daughters Jayci, Lilly, and Faye for all the warm smiles and hugs they provided for me as I worked on this dissertation. Benson H. Morrill vii CONTENTS Page ABSTRACT........................................................................................................................iii ACKNOWLEDGMENTS....................................................................................................v LIST OF TABLES..............................................................................................................ix LIST OF FIGURES.............................................................................................................xi LIST OF ABBREVIATIONS............................................................................................xii CHAPTER 1. REVIEW OF LITERATURE...................................................................... 1 Taxonomic History of Python regius ........................................................... 2 Ball Pythons in the Wild: Natural History and Reproduction......................4 Ball Pythons in Captivity: History of Husbandry and Reproduction.......................................................................................... 8 History of Quantitative Genetic Studies on Reptile Reproduction Traits.................................................................................................... 16 Use of Restricted Maximum Likelihood in Animal Breeding Genetics................................................................................................19 History of Reptilian Twinning Studies...................................................... 21 Summary.................................................................................................... 24 Research Goals and Possible Applications of Project............................... 25 References.................................................................................................. 28 2. EFFECTS OF CAPTIVITY ON FEMALE REPRODUCTIVE CYCLES AND EGG INCUBATION IN BALL PYTHONS (PYTHON REGIUS )................................................................................. 46 Introduction................................................................................................ 46 Materials and Methods............................................................................... 47 Results........................................................................................................ 50 Discussion.................................................................................................. 54 References.................................................................................................. 61 3. QUANTITATIVE GENETIC ANALYSIS OF BALL PYTHON (PYTHON REGIUS ) REPRODUCTION TRAITS.................................. 65 viii Abstract..................................................................................................... 65 Introduction................................................................................................ 66 Materials and Methods............................................................................... 68 Results........................................................................................................ 76 Discussion.................................................................................................