Response of adult dragonflies to prey of different size and colour in the context of anti-predator defences

Abstract

Warning coloration is used by many prey species to advertise their unpalatability to potential predators and the evolution of such signals is strongly influenced by predator behaviour. I begin by reviewing the past literature on the potential role of invertebrates in shaping the evolution of warning signals in aposematism and mimicry. I then describe an investigation of the behaviour adult dragonflies in response to artificial prey of varying shape and colour, to determine the role of these traits in influencing foraging decisions. In two experiments, dragonfly species and sex, and prey size, influenced prey selection. However, neither prey colour, nor its interaction with prey size, affected the rate of attack of dragonflies. Through a feeding experiment, I also found that dragonflies preferred to feed on insects with softer exoskeletons. The implications of these findings for the evolution of warning signals and mimicry in small aerial insects are discussed. iii ACKNOWLEDGMENTS I would first like to express my most sincere gratitude and thanks to my supervisor, Dr. Tom Sherratt, for his support, understanding, patience, and guidance throughout my Master's journey. I am honoured to have been given the opportunity to continue my education and grow as a scientist and person. I am extremely grateful for the people I have met, both academic and personal, the international conference in Exeter, England I was able to participate in, and the field research I conducted at the Queens University Biological Station-all of which were made possible by Dr. Tom Sherratt. Many thanks go to my thesis advisory committee for their advice and feedback during committee meetings as well as their patience as I finished my thesis. I would like to dedicate a special thank you to Dr. Changku Kang who helped me polish my R-skills, offered me valuable advice and guidance, and provided encouragement throughout my thesis. This appreciation is extended to my lab mates with whom I have made countless memories during my time in Ottawa. A special thank you goes to Ann Gomez for being a stellar field assistant and partner in crime during the field seasons and to Sophie Potter who went from co-worker, to roommate, to lifelong friend, with her limitless support throughout our friendship. I would also like to thank the staff at QUBS who made our stay comfortable by helping me with inquiries, providing hearty meals, and creating a community conducive to productivity and successful research. I am grateful for the QUBS community, full of passion, that has allowed me to meet so many interesting people and to make lasting memories that I will cherish forever. Finally, I would like to thank my mom and dad, Ha Nguyen and Bon Duong, for their unwavering and never-ending support throughout my academic endeavours. In addition, to family and friends for their support despite their concern that I would be leaving home to "do something with bugs". Lastly, to my partner, Eden Liu, who has been with me through all the ups and downs that came before, during, and af...