Thesis (Ph.D.)--Ohio University, August, 2008. / Title from PDF t.p. Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on July 28, 2009) Includes bibliographical references.

Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: David Cannatella and David Hillis. Vita. Includes bibliographical references. Also available from UMI.

Thesis (doctoral)--Ludwig-Maximilians-Universität München, 2005. / Title from PDF t.p. (viewed on May 10, 2006). Vita. Includes bibliographical references.

Simulated evolution is used as a tool for investigating the selective pressures that have influenced the design of animal signalling systems. The biological literature on communication is first reviewed: central concepts such as the handicap principle and the view of signalling as manipulation are discussed. The equation of “biological function” with “adaptive value” is then defended, along with a workable definition of communication. Evolutionary simulation models are advocated as a way of testing the coherence of a given theory. Contra some ALife enthusiasts, simulations are not alternate worlds worthy of independent study; in fact they fit naturally into a Quinean picture of scientific knowledge as a web of modifiable propositions. Existing simulation work on the evolution of communication is reviewed: much of it consists of simple proofs of concept that fail to make connections with existing theory. A particular model (MacLennan & Burghardt, 1994) of the evolution of referential communication in a co-operative context is replicated and critiqued in detail. Evolutionary simulations are then presented that cover a range of ecological scenarios; the first is a general model of food- and alarm-calling. In such situations signallers and receivers can have common or conflicting interests; the model allows us to test the idea that a conflict of interests will lead to an arms race of ever more costly signals, whereas common interests will result in signals that are as cheap as possible. The second model is concerned with communication during aggressive interactions. Many animals use signals to settle contests, thus avoiding the costs associated with fighting. Conventional game-theoretic results suggest that the signalling of aggression or of strength will not be evolutionarily stable unless it is physically unfakeable, but some recent models imply that cost-free, arbitrary signals can be reliable indicators of both intent and ability. The simulation, which features continuous-time perception of the opponent’s strategy, is an attempt to settle the question. The third model deals with sexual signalling, i.e., elaborate displays that are designed to persuade members of the opposite sex to mate. The results clarify the question of whether such displays are the pointless result of runaway sexual selection, or whether they function as honest and costly indicators of genetic quality. The models predict the evolution of reliable communication in a surprisingly narrow range of circumstances; a serious gap remains between these predictions and the ethological data. Future directions for simulation work are discussed.

<i>Leptophyes punctatissima</i> is unusual in that both sexes call. The male calls, the female replies and the male performs phonotaxis to the stationary female. Consequently mate choice could occur at either of two stages: first, during the interchange of calls and second, on the basis of proximate criteria once the male has approached. There is no evidence that females choose their mates on the basis of calling behaviour or call characteristics, though males that call more may achieve more matings. There is no evidence that body asymmetry has any effect on mating success for either sex. Males on a protein-supplemented diet do not produce larger spermatophores than males whose diet is not supplemented, but they do mate more often, possibly as a result of female choice but more likely because diet affects the rate at which males can produce spermatophores. Unsupplemented females mate more often than supplemented females, possibly as a result of male male choice or because they are seeking matings so that they can supplement their diet with spermatophores. Males give larger spermatophores to unsupplemented females. Larger males produce larger spermatophores. They also mate more often than smaller males, possibly as a consequence of female choice, success in male-male contests, or because larger males have larger energy reserves and can produce spermatophores more quickly. Larger females mate more often than smaller females but only when their diet was supplemented. Females lay more eggs the more times they mate. Females lay heavier eggs after their first mating than they do in later batches, and unsupplemented females lay more eggs after their first mating than supplemented females do, but otherwise female size, diet or level of asymmetry has no effect on the size or weight of eggs, or the number of eggs laid. The total weight of spermatophores females receive does not affect any measure of female reproductive success: neither fecundity, egg size or egg weight is affected by the weight of spermatophores females consume, irrespective of the diet the females were maintained on. Diet, size or number of matings does not affect female longevity.

Abstract This thesis deals with factors affecting mate choice as well as with genetic variation in male courtship song in Drosophila montana. Males, which produced song with a high carrier frequency, were found to court females, and also to succeed in their courtship more often than the males producing low frequency song. Male mating success correlated with the carrier frequency of his song recorded after, but not before, an "artificial winter", which suggests that a sexually selected male trait is sensitive to environmental factors. A high carrier frequency of male courtship song correlated positively with the survival rate of the male's progeny from egg to adulthood (indirect benefit for the female), but not with the fecundity of his mating partner (no direct benefit for the female). The heritabilities and the amount of additive and residual variation in male courtship song characters were measured in two populations using father-son regression and sib analysis. The songs of the males from one of these populations were analysed for a second time after the cold treatment. Most heritability values were insignificant, largely due to high residual variation. During the cold treatment, the additive variation increased and the residual variation decreased in almost all song traits. Increased variation in sexually selected traits may help the females to exercise selection between the males during the mating season of the flies in the wild in spring. This, and the fact that male song gives the female information about the male's condition/genetic quality suggests that in this species the evolution of female preferences for male song characters could have evolved through condition-dependent viability selection as postulated by "good genes" models. Variation and inbreeding depression/heterosis were studied in traits associated with fly reproduction using inbred D. montana strains. Songs, hydrocarbons and some behavioural traits of the flies varied significantly between strains. The strain of both sexes affected female egg-laying, and the female strain, also, the survival rate of the flies' progeny, in different intra- and interspecific combinations. Heterosis was found in the mating propensity of the flies and in the carrier frequency of the male song. Diallel analysis revealed unidirectional dominance towards higher carrier frequency. This direction is the same as the direction of sexual selection exercised by the females of this species suggesting that sexual selection could be a driving force in evolution of this song trait.

Extravagant male plumage traits in birds are a classic example of sexual selection. However we know very little about the units that selection is acting upon, the genes themselves – what are they and how are they influenced by sexual selection? In this study I focused on in the evolution and genetics of colouration the galliform birds. Several novel loci were used to create a well resolved phylogeny of this group. This was then used to investigate and reconstruct the evolution of sexual plumage dichromatism. Four pigmentation genes were sequenced in an array of galliform species. A measure of the rate of evolutionary change (dN/dS) at these loci was then compared between lineages with different strengths of sexual selection, using sexual dichromatism as the main index of sexual selection. I found evidence for sexual selection acting at the MC1R locus, in the form of a robust correlation between dN/dS and sexual plumage dichromatism that was not found at any of the other loci. I then went on to investigate the evolution and population genetics of MC1R in the grouse, focusing on the strongly dichromatic black grouse and the relatively monochromatic red grouse. I found some evidence for an adaptive change at this locus between these species. Finally I used a candidate gene approach to investigate the role of several genes in avian pigmentation using the Japanese quail (Coturnix japonica) as a model system. I found evidence that the avian agouti gene is involved in dorso-ventral pigmentation patterning and a regulatory mutation at this locus that produces a yellow phenotype. In addition point mutations at MC1R and TYRP1 were found to be responsible for producing pigmentation variants. I then compared the expression of several of these candidate genes in male and female common pheasants (Phasianus colchicus) and found lower TYRP1 expression in males. Knowledge of the genetic basis of secondary sexual traits and the action of sexual selection at this level could have important implications for our understanding of the process of sexual selection as a whole.

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.