Endocrine Regulation of Dynamic Communication Signals in Gymnotiform Fish

This dissertation, written by Anna Goldina, and entitled Endocrine Regulation of Dynamic Communication Signals in Gymnotiform Fish, having been approved in respect to style and intellectual content, is referred to you for judgment. We have read this dissertation and recommend that it be approved. iii DEDICATION This dissertation is dedicated to my parents, Gregory and Emma Goldin, and my husband, Dmitriy Krichevskiy. Without their love, support, and belief in my abilities, I would not have been able to complete this project. iv ACKNOWLEDGMENTS I am so grateful to my committee members; and guidance. Their expertise and constructive criticism has been essential to the success of this project. Especially, I would like to acknowledge my major professor, Philip K. Stoddard. From the beginning to the end of my graduate career, he has been an inspiration. In every conversation he conveyed the passion he has for science, mentorship and service. Through kindness, patience and a never-ending belief in my abilities, Phil gave me room to grow as a scientist and a teacher, helping me recognize my purpose along the way. My labmates were instrumental in the completion of this project. Through all the successes and failures of graduate school, they made the graduate experience unforgettable. Especially, I would like to thank Dr. Michael Markham for his generous invitation to participate in what became chapter II of my dissertation. Without him this dissertation project would not exist. helped me learn new techniques, troubleshoot failed experiments, analyze data and edit manuscripts. The undergraduate students whom I've had the pleasure of training and working with; taught me so much about mentorship and humility. v I would also like to thank my fellow graduate students and faculty on the 2 nd floor of the HLS building. Their humor, support, and friendship made HLS always feel like a seond home. Communication signals are shaped by the opposing selection pressures imposed by predators and mates. A dynamic signal might serve as an adaptive compromise between an inconspicuous signal that evades predators and an extravagant signal preferred by females. Such a signal has been described in the gymnotiform electric fish, Brachyhypopomus gauderio, which produces a sexually dimorphic electric organ discharge (EOD). The EOD varies on a circadian rhythm and in response to social cues. This signal plasticity is mediated by the slow action of androgens and rapid action of melanocortins. My dissertation research tested the hypotheses that (1) signal …