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Honours supervisors and projectsDr. Phillip Byrne Office: G Building #18 Behavioural Ecology is a branch of Ecology that focuses on understanding how variation in behaviour within and between species evolves. Put simply, it is the study of why animals behave (or misbehave) the way they do. My research focuses on understanding how behaviour is shaped by sexual selection. In brief, I am interested in how mate choice, sperm competition and sexual conflict shape the evolution of reproductive strategies and mating systems. My approach to testing evolutionary theory is multidisciplinary, combining behavioural observation with comparative analyses molecular genetics and quantitative genetics. While I am open to using diverse organisms to evaluate theoretical models, I generally focus on frogs. Frogs are ideal for studying how sexual selection operates because they often display conspicuous mating behaviour and can be easily marked, identified and observed. Furthermore, frogs are characterised by external fertilization, which permits manipulation of parentage and the conduction of sophisticated experiments designed to unravel how genes influence animal behaviour. In 2008 I am offering three honours projects. One will be co-supervised with Bob Wong and will investigate the role of human voice pitch in male and female mate choice. The other two projects will use the toadlet Pseudophryne bibronii as a model system. Toadlets are abundant and widely distributed between Queensland and Victoria and are characterised by a unique system of terrestrial breeding. In autumn, males build nests under leaf litter along dry creek lines and call to attract females. Females deposit their eggs in the nest and embryos then rapidly develop into tadpoles. However the tadpoles do not hatch immediately but remain within egg capsules and enter a state of suspended development. Tadpoles remain in this state until winter rainfall floods nests and triggers hatching. I have spent 3 years working with the toadletsand have discovered that they are extraordinary animals characterised by an array of fascinating behaviours. Because the toadlets are abundant and have a discrete breeding period they are ideal for short-term research projects. Details of the two ‘toadlet projects’ I have on offer are outlined below. The role of human voice pitch in male and female mate choiceThe way Human beings choose their mates is a complicated process that involves a combination of visual, chemical and acoustic cues. The role that acoustic cues (sound) plays in mate choice is only just beginning to be understood. Recent work has unveiled that human females prefer men with lower pitch voices, whilst men prefer women with higher pitches. It has also been established that pitch is affected by testosterone levels. What remains to be investigated is whether ‘pitch preferences’ remain constant when other cues vary (e.g. physical appearance), and how interactions between different cues ultimately affect mate choice. A number of experimental approaches could be taken with this project depending on how ‘creative’ the student wants to be! Studies of human mate choice almost invariably receive considerable media attention, so the project has the potential to be high profile. If you are interested please come and talk with myself, or Bob Wong. References
The role of pheromones in frog communication Pheromones are chemicals released by animals that stimulate behavioural responses in members of the same species. It is now well established that many animal groups use pheromones in social communication. Surprisingly, however, we know very little about chemical communication in anuran amphibians (frogs and toads). Many anurans possess large glands that release odorous substances, so chemical communication is likely to be a widespread mode of conveying information. Recently, I discovered that chemosignals play a crucial role in regulating the sexual behaviour of terrestrial toadlets because pheromones operate as sex attractants and also aid in mate location. Continued investigating into the role that chemicals play in toadlet communication is now required. The project will involve two components. First, it will aim to isolate the active peptides that give toadlet pheromones their potency. To address this question it will be necessary to collect gland secretions from breeding toadlets, and create ‘pheromone profiles’ using gas or liquid chromatography. Assistance from staff in the school of biochemistry could be sought if necessary. The second aspect of the project would focus on investigating the role of pheromones in sexual selection. There are many questions that could be addressed but the most rewarding are likely to be 1) Do ‘pheromone profiles’ vary significantly between individuals, and does this variation influence attractiveness and mate choice? 2) Do pheromones signal a toadlet’s genetic quality 3) Do males use pheromones to mark and defend their nest sites? 4) Do acoustic signals operate more effectively when combined with pheromones? There are also many other questions that could be investigated depending on what aspects of behaviour the student finds most interesting. References
Female mate choice in terrestrial toadlets: Do males advertise good genes or good homes? When females choose mating partners their decisions are typically based on whether they can accrue direct material benefits (e.g. good homes) or indirect genetic benefits for their offspring. Among anuran amphibians(frogs and toads), it is well known that females discriminate between males based on their call traits as well as the quality of their territories. What remains to be unravelled is how these choices influence offspring viability. That is, are offspring incubated under preferred environments fitter, and do female preferences for certain call traits result in offspring having superior viability? Terrestrial toadlets offer a unique opportunity to address these questions. Females lay eggs in terrestrial nests that vary substantially in quality (soil moisture, soil ph and exposure to UV light) and males also vary in call characters (e.g. frequency) that are likely to reflect genetic quality. Within nests, embryo deformity is quite common, which strongly suggests that a female’s choice of either mating partner (paternal genes) or nest site (home), critically affects her reproductive success. The aim of this project is to determine the extent that offspring viability is related to variance in incubation environment versus male genetic quality. To address this aim, the Honours researcher would need to conduct experiments in both the field and the laboratory. Fieldwork would entail recording and quantifying male calls and quantifying female mate preferences by conducting choice trials. Lab work would require rearing offspring from ‘preferred’ and ‘non-preferred’ males’ and quantifying offspring survivorship, growth and performance. Lab work would also entail rearing embryos under a variety of environmental conditions to determine how ‘incubation environment’ affects offspring viability. This is an ideal honours project because it will quickly generate substantial data. References
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