T h e E volutionary O r ig in s o f V ib r a t o r y S ig n a l s in D r e p a n id a e C aterpillars : A C o m p a r a t iv e S t u d y o n M o r p h o l o g y , P hylogenetics a n d B e h a v io u r by Jaclyn L. Scott A thesis submitted to the Faculty of Graduate and Postdoctoral Affairs in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biology Carleton University Ottawa, Ontario, Canada © 2012 Jaclyn L. 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Canada A b s t r a c t Animal communication signals can be highly elaborate, and researchers have long sought explanations for their evolutionary origins. Animal communication theory holds that many signals evolved from non-signalling behaviours through the process of ritualization. Empirical evidence for ritualization is limited, as it is necessary to examine living relatives with varying degrees of signal evolution within a phylogenetic framework. I examined the origins of vibratory signals in Drepanidae caterpillars using comparative and molecular phylogenetic methods. I demonstrated that variation exists in morphology of signalling structures, general life-history characteristics related to signalling, and territorial behaviour by studying morphology in 19 species and behaviour in 11 species. I developed a molecular phylogeny of the Drepanidae onto which these characters could be mapped to test specific hypotheses on to the origin of signalling. These hypotheses included: 1) anal scraping derives from crawling towards an intruder; and 2) mandible scraping derives from lateral head hitting. My results support these hypotheses based on morphological, behavioural and kinematic data, thereby providing strong empirical evidence for the origins of communication signals. My thesis also demonstrates that vibratory communication is widespread and variable in this group of caterpillars, adding much needed information on this mode of communication in larval insects. Finally, I provide several lines of evidence to suggest that larvae that invest in leaf shelters defend these shelters from conspecifics using vibratory communication, which contributes to a growing body of information on this topic in caterpillars. A cknowledgements First and foremost, I would like to thank my degs friends and family for their endless support and guidance throughout the years. In particular, I will be forever grateful to my wonderful husband, James, for always being there for me, in the good times and the bad, and for fully supporting me throughout this stressful endeavour. I could not have done this without you! A big thank-you to my loving parents for always encouraging me to excel in everything I do, and for providing me with the solid foundation I needed to accomplish my goals. You are not only my parents, but also my mentors, role models, and friends. I would also like to thank my sister for being my best friend and constant support system throughout the years, and my brother for reminding me not to take life so seriously. Finally, probably the most important members of my family, I would like to thank my dogs, Lexie, Penny, and Meesha (in that order), and my cats, Bagheera and Uter, for providing me with their infinite love and devotion, and for spending many hours sleeping beside me as I wrote my thesis. I would also like to extend my gratitude to all of the past and present members of the Yack lab, who are not only my lab mates, but I have grown to be some of the most important people in my life. A special thanks to Veronica (Ron) Bura and Sarah Matheson, for helping tremendously with my project, for being my best friends, my support system, my sentence structure helpers, and for making learning fun! I don't know what I would have done without you! Thank you to Alan (AJ) Fleming for being my go­ to entomology expert, and for taking me out for a drink whenever I needed it most. I would also like to thank Katie Lucas, Amanda Lindeman, Laura McMillan, J-P Fournier, and Sen Sivalinghem for their advice and support along the way; to Abeer Sami, Shannon Henderson, Sarah Davis, Tamara Nevills and Tiffany Eberhard for help with data collection; and to members of the Smith lab, Robert Smith, Denis Lafontaine and Melissa Begin, in particular, for help with the molecular genetics portion of my research. A well-deserved thank-you to all others that helped with data collection and analysis for my project. Thanks to K. Silvonen, S. Corver, T. Muus, L. Scott, J. Miall, H. Beck, Y.L. Chen, K. Eda, C.H. Wei, S. Wu, and J. Sohn for collecting wild moths; to C. Mittner, K. Mittner, J. Heppner, and P. Gentili-Poole for providing specimens in alcohol; to Dr. Shen Horn Yen for providing specimens from Asia and for conceptual advice on behaviour and morphology; to Dr. Ivar Hassenfuss for providing unpublished observations on Drepanidae caterpillars; to Dr. Jeff Skevington for help with phylogenetic analysis; to Dr. Jeff Dawson for help with acoustic analysis; and last but not least, to Dr. Akito Kawahara for his immense help with molecular phylogenetic data collection and analysis. I also wish to thank my committee members: Dr. Myron Smith for allowing me use of his lab for my molecular genetic work, and for providing me with lots of advice on molecular genetics and all other aspects of my project; and Dr. Charles Darveau for his invaluable comments and input on my project. Last, but certainly not least, I am forever grateful to my supervisor, Dr. Jayne Yack, for pushing me all these years to succeed and for always having my best interest at heart. Thank you for challenging me, for providing me with the opportunity to work on this wonderful project, for keeping me interested in science, for correcting my grammar, and for all the advice you have given me throughout the years. You will always be like a second mother to me (a very picky mother, but a loving one, all the same!). Funding for this research was provided by the Natural Science and Engineering Research Council of Canada (NSERC) Discovery Grant, and the Canadian Foundation for Innovation (CFI) to Dr. Jayne Yack. Additional funding was provided by NSERC (PGS-M and CGS-D), Carleton University, the David and Rachel Epstein Foundation, and a Wyndham Scholarship for Graduate Students in Biology to Jaclyn Scott. v T a b l e o f C o n t e n t s A b s t r a c t ...............................................................................................................................................................n A cknowledgements ................................................................................................................................... h i T a b l e o f C o n t e n t s ...................................................................................................................................... v i L is t o f T a b l e s ................................................................................................................................................x n L is t o f F i g u r e s ............................................................................................................................................x iii L is t o f A p p e n d ic e s .................................................................................................................................... x v i L is t o f P ublications ..............................................................................................................................x v ii C h a p t e r 1: General Introduction .................................................................................................... 1 1.1 The evolutionary origins of animal