Cyphoderris Monstrosa (Orthoptera: Haglidae)

Effect of Acoustic Signaling, Metabolic Rate, and Size on Territoriality in Male Cyphoderris monstrosa (Orthoptera: Haglidae) By Terrence T. Chang Ecology and Evolutionary Biology University of Toronto A thesis submitted in conformity with the requirements for the degree of Master of Science. © Copyright by Terrence T. Chang 2015 Effect of Acoustic Signaling, Metabolic Rate, and Size on Territoriality in Male Cyphoderris monstrosa (Orthoptera: Haglidae) Terrence T. Chang Masters of Science Ecology and Evolutionary Biology University of Toronto 2015 Abstract During territorial interactions, male ensiferan Orthoptera often stridulate before physical combat. Song is correlated with competitive ability; therefore, it is a reliable signal for resource holding power. Size and metabolic rate are also indicators of aggressiveness. Cyphoderris monstrosa (Orthoptera: Haglidae) are relatively insensitive to the frequency content of their own song, however, males use acoustic signals in the context of competition. Here, I examined size, diet, time spent singing, and metabolic rate with C. monstrosa territoriality. Using a round-robin tournament, I compared performance of males fed with a protein-supplemented diet to males fed with a low-protein diet. I measured body structures used for fighting, duty cycle during competition, and metabolic rate at two temperatures (22°C and 10°C). Competition in C. monstrosa is influenced by singing ability, physiological performance, and body and head size where winners have higher duty cycle, lower metabolic rates in cold, larger bodies, and smaller heads. ii Acknowledgements None of this would have been possible without the support and guidance of my advisor, Andrew C. Mason. I am most grateful for his enthusiasm, friendship, and uncanny ability to troubleshoot Cyphoderris problems – truly a “Cyphoderris whisperer”, if ever one existed. I could not imagine having a better mentor and advisor for my studies. I would also like to thank the rest of my committee: Maydianne Andrade and Darryl Gwynne Their insights, perspectives, and questions motivated me to expand and continue my research. Also, I must thank Kevin Judge for all the discussion and advice he offered for this project. I would also like to thank Brock Fenton, who started me on this journey, and Jeremy McNeil, without whom I would not have found this lab. Both are constant sources of encouragement and are largely responsible for my decision to pursue this path. I thank my Cyphoderris wranglers: Niroshan Ranjan, Jeff Garel, Keerthana Rajkumar, Jill Thaker, and Tameem Al-Ozzi. Their steady help with data collection and taking care of specimens was a great relief and allowed me to maintain some semblance of sanity. I also thank Derrick Groom for his assistance with the respirometry equipment. AJ Masson, Sen Sivalinghem, Natasha Mhatre, and Jerry Pollack were sources of valuable discussion and helped me approach my project from different perspectives. Erica Morley and Ryo Nakano also helped with collecting, for which I am grateful. Special thanks goes to Megan McPhee who was a great source of support, both academic and personal. When I started this project, I did not know I would find my best friend. From stand-up shows and inordinately long dinners to writing sessions and discussions, I am glad to have shared this experience with her. I am also fortunate to have the unwavering support and enthusiasm of Joyce Lai. There are simply not enough words to describe my gratitude. Finally, I am especially grateful to my parents, Louis and Winnie Chang. Their constant support has been the greatest gift. I would never have enjoyed so many opportunities if not for them. iii Table of Contents Abstract . ii Acknowledgements . iii Table of Contents . iv List of Tables . v List of Figures . vi Introduction . 1 Animal Communication . 1 Competition in Orthoptera . 7 Natural History of Cyphoderris monstrosa . 10 Methods . 14 Specimen Collection and Husbandry . 14 Competitive Interactions . 14 Metabolic Rate Measurements . 16 Morphometrics . 17 Statistical Analysis . 17 Results . 19 Discussion . 21 References . 27 Tables and Figures . 35 iv List of Tables Table 1: Final model from generalized linear mixed model of contest outcomes and duty cycle in competing C. monstrosa males. 35 Table 2: PCA results for body size metrics . 36 Table 3: Final model from generalized linear mixed model analysis of overall status in competing male Cyphoderris monstrosa . 37 v List of Figures Figure 1: Map of Cyphoderris spp. distribution in Western Canada and USA . 38 Figure 2: Diagram of arena used for Cyphoderris contests . 39 Figure 3: Relationship of duty cycle and outcome of territorial interaction . 40 Figure 4: Body size of winners and losers . 41 Figure 5: Head size of winners and losers . 42 Figure 6: Ratio of metabolic rate at two temperatures in winners and losers . 43 vi Introduction Animal Communication Communication is the transfer of information from a sender to a receiver where the behaviour of the receiver is affected (Bradbury & Vehrencamp, 2011). Communication occurs with the use of signals which arise from ritualization or exaggeration of non-signaling behaviour and exploitation of pre-existing sensory biases (Lorenz, 1966; Bradbury & Vehrencamp, 2011; Scott- Phillips et al., 2012). As such, signals are based on visual, chemical, acoustic, tactile, or behavioural traits used in acquiring and maintaining resources (Hasegawa et al., 2011). The function of communication is heavily studied in the contexts of mating, competition, foraging, predator deterrence, and parent-offspring interaction (Dodson et al., 1983; Mason, 1996; Hare, 1998; Cocroft, 2005). Due to the inherent nature of communication, signals are under co- evolutionary pressures exerted from both signaler and receiver. Signaling traits persist if there are overall benefits to both parties. Several ways in which the use of signals can directly influence the fitness of individuals include: securing mating opportunities; energetic costs of signaling; exposure to risk of predation or parasites; discovery of foraging opportunities; deception or manipulation by others; and establishing dominance in a hierarchy (Bovbjerg, 1953; Belwood & Morris, 1987; Snedden & Sakaluk, 1992; Endler, 1993; Hughes et al., 2012). In this thesis, I explore the principles governing success in male territorial contests of the relict flightless haglid, Cyphoderris monstrosa (Orthoptera: Haglidae). Based on previous literature of C. monstrosa, acoustic signaling plays a role in predicting contest outcome (Mason, 1996; Morris et al., 2002). Here, I re-examine the effects of singing effort as well as differences in singing between individuals maintained on different diets. In addition, I observed the effects of size and physiological performance on success in competitions. 1 Animal displays are diverse and vary in form, size, modality, and costs of production and reception (Dawkins, 1993; Shaw, 1994; Galeotti et al., 2006; Cady et al., 2011). There is no general principle of signal design due to the many possible combinations of selective pressures on signals resulting in high diversity (Dawkins, 1993). Selection pressures that may influence signal design include previously mentioned fitness consequences for signalers and receivers (i.e. degree of conflict or cooperation) as well as, signal efficacy including production, transmission, and reception (Dawkins, 1993; Bradbury & Vehrencamp, 2011). The type of selection signals undergo depends on how signaler intention and receiver preference interact: if they coincide, then selection is stabilizing; if the signal is outside the range of preferences, then selection is directional; if there is preference for extreme types, then selection is disruptive (Ryan & Rand, 1993; Naisbit et al., 2001). Signals also vary in complexity, ranging from simple signals consisting of one component to highly complex signals comprised of multiple components that may be targeted to multiple sensory systems or modalities (Candolin, 2003). Determining information content of multicomponent or multimodal signals and resulting receiver responses explains how selection shapes and maintains these signals (Candolin, 2003; Ossip-Klein et al., 2013). Though this task is inherently difficult, using controlled experiments in a comparative approach, we can determine qualities that correlate to a set of signals. For example, numerous studies have broken down calls of various katydid species into their fundamental structural components to examine the content of each component (Simmons & Bailey, 1993; Galliart & Shaw, 1996; De Luca & Morris, 1998; Korsunovskaya, 2009). Depending on the medium through which signals are transferred, they may also attract unintended receivers such as predators which can affect both signaling and receiving behaviour (Hughes et al., 2009). In some instances, multimodal signaling may evolve as an antipredator behaviour. In the Neotropics, 2 katydids (Tettigoniidae) face strong predator pressure from insectivorous bats. Katydid calling and courtship song is highly localizable for bats (Belwood & Morris, 1987). As a result, katydids have shortened acoustic signals and developed the use of tremulatory signals – in at least one species, vibrations have completely replaced acoustic signals (Belwood & Morris, 1987; Morris et al., 1994). In addition to the production and propagation of signals, reception of these signals adds another dimension of complexity to communication. Based on how receivers perceive

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