FEMALE COMPETITION and DISPLAY in KRIBENSIS (Pelvicachromis Pulcher), a WEST AFRICAN CICHLID
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FEMALE COMPETITION AND DISPLAY IN KRIBENSIS (Pelvicachromis pulcher), A WEST AFRICAN CICHLID Lynn Marie Drennan B.S., California State University, Sacramento, 2003 THESIS Submitted in partial satisfaction of the requirements for the degree of MASTER OF SCIENCE m BIOLOGICAL SCIENCES (Biological Conservation) at CALIFORNIA STATE UNIVERSITY, SACRAMENTO FALL 2006 FEMALE COMPETITION AND DISPLAY IN KRIBENSIS (Pelvicachromis pulcher), A WEST AFRICAN CICHLID A Thesis By Lynn Marie Drennan Approved by: , Committee Chair Dr. Ronald Coleman Dr. Brett Holland ------' Third Reader . J am1e e1te Date: 2006 ~7.) 11 Student: Lynn Marie Drennan I certify that this student has met the requirements for the format contained in the CSUS Thesis Format Guide from Graduate Studies, and fua:t this thesis is suitable for shelving in the Library and credit is to be awarded for this thesis. /J-)~.,---, Dr. Coordinator . Date. Department of Biological Sciences 111 Abstract of FEMALE COMPETITION AND DISPLAY IN KRIBENSIS (Pelvicachromis pulcher), A WEST AFRICAN CICHLID by Lynn Drennan The field of sexual selection has focused on male-male competition and choice by females. This type ofintrasexual competition and intersexual selection (mate choice) has been well documented experimentally. The opposite situation, female-female competition and choice by males, has only been considered fairly recently and in a few situations, typically those studying so called sex-role reversed systems. By conducting experiments on the biparental cichlid fish, Pelvicachromis pulcher, commonly called the kribensis, my objectives were to determine if a kribensis female will compete against another kribensis female for the attention of a kriben.Sis male and to see if a kribensis male will choose his mate based on the kribensis female's display competition. More specifically, I looked at whether bright females, larger females or albino females . provided longer display times when competing for a male mate. I also looked at whether a male was more likely to choose a bright, a large, or an albino female versus duller or smaller females. I predicted that kribensis females do c~mpete with displays against other kribensis females and that the bright, large, and albino females will compete the most. I also predicted that kribensis males will choose their mates based on the fem.ale's lV display competition as well as the male choosing a bright, large or albino female. To test my objectives and predictions, research was conducted in the Evolutionary Ecology of Fishes Laboratory at California State University, Sacramento from Summer 2005 to Summer 2006. The experiment consisted of putting two females into an experimental aquarium and then introducing a male. The females were allowed to use displays to compete for a 30 minute trial. The display times of the females were recorded then they, along with the male, were left for five days so that the male could perhaps choose a female mate. As predicted, the females were found. to compete against each other for the males, with the bright, larger, and albino females competing the longest, and there was a general trend for the male to choose brighter and larger fe~ales. These findings provide evidence that female-female competition does occur outside of sex-reversed and uniparental mating systems and should be considered in understanding the sexual systems of a wider range of animals. Committee Chair v Acknowledgements I would like to thank Dr. Ronald Coleman for allowing me the excellent opportunity of working on research involving the wonderful fish known as cichlids. Without his help and guidance this research would never have been completed. I am extremely grateful to my supervisory committee (Dr. Ronald Coleman, Dr. Brett Holland, and Dr. Jamie Kneitel) for their unending support, guidance, and patience throughout my research experience. I appreciate the work and guidance provided by the Department Graduate Committee (Dr. Jim Baxter and Dr. Tom Landerholm) and the Department Chair, Dr. Nicholas Ewing. I would like to thank all of my instructors at CSU, Sacramento for their unending love of biology, their various perspectives and their real world knowledge that they willingly shared with me. I thank my lab mates for being there when I needed help or if I needed to talk about classes, problems, etc. I would like to thank the American Cichlid Association (ACA), the Pacific Coast Cichlid Association (PCCA), and the Aquatic Specialties and Pets (ASAP) for the financial consideration and fish supply that was provided so that I could complete my thesis work. I thank my supervisors (Rhonda Rios-Kravitz and Barbara Stephens) at the CSU, Sacramento Library for being understanding and helpful throughout this whole educational process. Lastly, but definitely not least, I want to thank my whole family (my parents Brad and Deb Drennan, my sister Lauri Drennan, and my grandparents Gordon and Judy Muir, Pam, Danny, Kaleen and Krislyn Patterson, and Dr. Michael Dierker) for their support and encouragement throughout this whole ordeal because without them I would never vi had the gumption to complete this work. They gave more support then they will ever know. For anyone I may have missed, I thank everyone for what they did for me that allowed me to complete this important goal in my academic career. vii Table of Contents Page Acknowledgements .••••••.••••••••••..•••••••••••..•••••••..••••••••••••..•••••••••••••••••••••••••••..•••••..•••••••••••••• vi List of Tables ..•••••.•••••••..••..••..•...••...•..••.••••...••.•.•.•••••..••...•.•.••...••.••..••••••••••..•••••••••••••..••••••. ix List of Figures ••..•.•.•••••..••••••••••...•••••...••••••.••.•..•.•••••.••••••.••••.••••••..••...•..••..••..•••••••••••.•..•..••••• x INTRODUCTION•••••••.••••••..••••••...•••.••••.•••.••••.••...•..•••••••••.••••••••••••••••••••.••••••.•••••••••••••••••••• 1 Background ..................................................................................................................... 2 Mate Choice .................................................................................................................... 7 Sex-role Reversal .......................................................................................................... 12 Monogamy .................................................................................................................... 15 Parental Care ................................................................................................................. 18 Communication in Fish ................................................................................................. 20 The Kribensis ................................................................................................................ 28 Objectives ............................. '. ....................................................................................... 32 MATERIALS AN'D METHODS ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 33 Study Animals ................................................................................................ i··········· ... 33 Animal Care .................................................................................................................. 33 Test Aquaria .................................................................................................................. 34 Experimental Setup for Test Trials ............................................................................... 36 Preliminary Experiments .............................................................................................. 36 Experiment 1 ................................................................................................................. 3 7 Experiment 2 ................................................................................................................. 3 7 RESULTS ••••••••••••••••••••••••••••.•••••••••••••••••••••••••••••••••.••••••••••••••••••••••••••••••••••••••••••••••••••••••••• 39 DISCUSSION ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••..•••••..••••• 43 CONCLUSION •••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••.•••••••..••..•••••••••.•••••• 51 LITERATURE CITED ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••.••••••••••• ,••••••••••••••••••••• 52 APPENDIX ••••.•••.••••••••••••••••••••••••.•••••••••••••••••••••••••..••••••..•••.••••••••••.•••••••••••••••••••..•••••..•••.•. 57 Vlll List of Tables Table Page Table 1. Sex-role reversed species vs. kribensis. Kribensis is not considered to exhibit a conventional (males compete· and females choose) sex role system because the females compete, but they are also should not be considered a sex-role reversed species. The differences between the sex-role systems and kribensis are shaded. ..................................................................................................31 Table 2. Preliminary data table. a.) Bright vs. Dull and Large vs. Small female - female competition display times. b.) Bright vs. Dull and Large vs. Small male choice chart ................ : .....................................................................................57 Table 3. Final data table. a.) Bright vs. Dull, b.)Large vs. Small, and c.)Normal vs. albino female-female competition display times. d.) Final data- Bright vs. Dull and Large vs. Small male choice charts .........................................................................................