ABG student Bhagya Herath has had her doctoral thesis approved by Academic Board in August 2021. Congratulations Dr Bhagya Herath.
Title: Multidimensional complexity of Communication Signals of a Model Anuran, Litoria fallax (Pelodrayadidae), amid Genetic, Ecological and Social Constraints
General Abstract: Complex communication systems are widespread among animals. To fully understand their functional and evolutionary significance, we must examine each dimension of communication together with possible genetic, environmental and ecological constraints. With the extensive use of acoustic signals, anurans are considered as excellent model systems for studying the evolution of such communication systems However, there is a lack of detailed knowledge on the multi-level complexity of the communication systems of anurans compared to other taxa. Litoria fallax, or the eastern dwarf tree frog, is a native Australian pelodryadid with a broad distribution range along the east coast. I provide a detailed quantitative description of the acoustic repertoire of this species, describing multiple levels of complexity in their acoustic repertoire, comprised of three note types arranged into monophasic and diphasic calls with a graded arrangement. Using female-choice experiments on the most common diphasic call type, I identified that female frogs prefer the shorter note type over the longer. Call types in a call sequences of this species are generated in a unique pattern and I used information theory to consider complexity in relation with the conspecific acoustic environment. I then compared the advertisement notes across known genetic clades of the species along with a variety of other environmental and ecological factors. The results suggest that geographic variation observed among the populations is both shaped by phylogenetic and local selection pressures. Choice experiments with female frogs demonstrated that they are sensitive to the phenotypic plasticity of the population variability as they chose local acoustic cues over foreign ones. In my final empirical chapter, I examine multimodal signalling of the species to report on the use of visual signals during male-male agonistic interactions. Playback experiments reproducing the multimodal structure of signals suggested both male and female frogs were more likely to choose the multimodal signal over acoustic only stimuli. Taken together, my thesis provides novel data on the complex communication system of an Australian anuran. This is one of the very few studies that used Information theory on the communication system of an amphibian species indicating the importance of implementing such methodologies in disentangling the multiple factors effecting complex communication systems.
