I recorded acoustic and visual components of Indian Peafowl (Pavo cristatus) mating displays at the Assiniboine Park Zoo, in Winnipeg, Manitoba, Canada. I determined that males produce infrasound (<20 Hz) in their train displays, and documented responses of peafowl to playbacks of both audible and infrasonic components of their vocalizations and train displays. Peafowl responded to infrasonic signals by increasing alertness and locomotory behaviours, while males also responded by calling. In response to audible call playbacks, males called and faced the playback unit while females increased locomotion and alertness, though peafowl did not respond to audible signal components from the train display, suggesting that infrasonic components constitute the essential signal component within those displays. Beyond revealing a critical role of acoustic signals in modulating interactions among peafowl, my results provide the first empirical evidence of a bird producing and perceiving infrasound as a signal.

While the phenotypic effects of sexual selection have been well studied, the consequences for population mean fitness remain unclear. Additionally, there is a need to more fully characterize how various forms of inter- and intrasexual selection combine to affect the evolution of traits under sexual selection. Here, I address these issues as they relate to male territoriality in Drosophila serrata, a model system for the study of female preference for male pheromones. First, I demonstrate that territoriality occurs and is a likely component of male sexual fitness. Results from a phenotypic manipulation indicate that territorial success was also condition-dependent, and that sexual selection against low condition males tended to be stronger given a high opportunity for territory defense. Territorial success depended on body size but not on pheromones. How this and other components of male mating success interact to affect trait evolution and population mean fitness remains an important area for future study.

I recorded acoustic and visual components of Indian Peafowl (Pavo cristatus) mating displays at the Assiniboine Park Zoo, in Winnipeg, Manitoba, Canada. I determined that males produce infrasound (<20 Hz) in their train displays, and documented responses of peafowl to playbacks of both audible and infrasonic components of their vocalizations and train displays. Peafowl responded to infrasonic signals by increasing alertness and locomotory behaviours, while males also responded by calling. In response to audible call playbacks, males called and faced the playback unit while females increased locomotion and alertness, though peafowl did not respond to audible signal components from the train display, suggesting that infrasonic components constitute the essential signal component within those displays. Beyond revealing a critical role of acoustic signals in modulating interactions among peafowl, my results provide the first empirical evidence of a bird producing and perceiving infrasound as a signal.

In the first part of this thesis, a general one dimensional theory of strategically determined phenotypes is developed and applied to biological signalling games. Abstract modular modelling techniques are utilised to solve hitherto analytically intractable problems including error-prone signalling, and how to incorporate genetic features into optimization models. Links are drawn between previous biological models, such as the War of Attrition and Strategic Handicap mod- els. Mistakes in previous biological models are recognised and, where possible, rectified. A number of novel insights into biological phenomena arising from the models are presented, including analyses of: when free signals are possible; honest signalling of future paternal investment; dimorphic signals; the effects of the mechanisms of female discrimination in sexual selection on male signalling strategies; and the effects of relatedness on the magnitude and stability of equi- librium signalling strategies. It is argued that Zahavi's proposed demarcation between signal selection and natural selection is unjustifiable from a theoretical perspective. The second part of the thesis concerns the epistatic handicap process of sex- ual selection. Unlike the conditional and revealing handicap mechanisms, the epistatic or 'Zahavian' handicap mechanism of sexual selection has hitherto found scant support in the theoretical literature, as it appeared to function only under the most extreme conditions. A continuous game theory model, a quantitative genetics model, and a three locus major gene model are presented which show that the epistatic handicap mechanism can function, independent of the Fisher process of sexual selection, under reasonable assumptions. More- over, the game theory model illuminates the connection between the strategic and epistatic handicap mechanisms. The quantitative genetics and major gene models, together with a fourth model, are also used to show that a general argu- ment concerning indirect genetic correlations, which has appeared in a number of papers on sexual selection, is specious. Finally, a general theorem on games that satisfy the single-crossing condition (also known as the sorting, Spence-Mirrless, or constant sign condition) which underlies many of the results presented in the first part of the thesis is proven in appendix C. Applying a limit result to this general theorem provides a new proof of, and extensions to, Nash's existence result for equilibria to strategic- form games without having to resort to Kakutani's fixed point theorem.

No description available.

Thesis (M.S.)--Auburn University, 2007. / Abstract. Includes bibliographic references (ℓ. 16-21, 50-51)

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Thesis ( Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 136-139). Also available via World Wide Web.

Thesis (Ph.D.)--Australian National University, 2003.

Thesis (M.S.)--Eastern Illinois University, 2008. / Includes bibliographical references (leaves 33-35).