No description available.

In this thesis my initial goal was to use yellow warblers to examine the effect of paternal care on female mate choice. I first examined whether mate choice based on paternal care could be considered adaptive. Paternal care was variable among males and important to female fitness, but, contrary to a previous report, male chest striping could not be used to predict paternal care. Females did not compensate for reductions of male parental care, which resulted in significantly reduced nestling growth. In chapter two I tested the idea that monogamy in birds is maintained because of the need for biparental care. I reduced the need of strict biparental care by providing pairs at some nests with supplemental food, and found that the main effect of supplemental food was on maternal, not paternal behaviour. The first two chapters suggest that males and females provide for their brood independently from each other, which is in disagreement with current models on the maintenance of biparental care. These models assume that any given factor must affect maternal and paternal care equally for biparental care to be maintained. In Chapter three I showed that the effects of brood size and nestling age on parental care are similar for both sexes. In Chapter four I deal with age-related changes in reproductive success and the possible effects on female mate choice. Age affected the likelihood of breeding in females, but only the time of breeding in males. These changes were accompanied by age-related increases in size in both sexes. These results raise the possibility of age-related increases in parental ability, and female preference for older males.

Zaprionus tuberculatus and Z. sepsoides are two sibling species of drosophilid fly which are sympatric throughout tropical Africa. Their sexual behaviour has previously received little study. In this thesis, the courtship behaviours of the two species are described, and the descriptions compared with previously published descriptions by other authors. Three different laboratory-bred strains of Z. sepsoides, and two of Z. tuberculatus, were studied, and their male courtship "songs" (produced by male wing vibration) were compared. The main objects of the project were to study the mechanisms by which members of these two species identify the sex of other individuals (sexual dimorphism being slight); and the isolating mechanisms operating between the two species. Preliminary observations suggested that males could probably identify females by chemosensory cues. However, males would sometimes also court each other. Further experiments on the males' ability to distinguish sex-specific pheromones gave ambiguous results. There were no grounds to suspect that females could distinguish between the sexes by chemosensory means, and further experiments gave no evidence for such an ability. Preliminary observations indicated that that there was an effective pre-mating reproductive barrier between male Z. sepsoides and female Z. tuberculatus, but male Z. tuberculatus were sometimes able to copulate with female Z. sepsoides. These interspecific matings resulted in infertile eggs. Further experiments seemed to confirm that the isolating mechanism between the two species is asymmetric, the onus of species recognition lying largely on Z. sepsoides. Male Z. sepsoides apparently recognise a female's species by chemosensory means, while female Z. sepsoides recognize a male's species by his "Type-2" courtship "song". There was also some evidence that female Z. sepsoides could distinguish between males of the two species by olfactory means. Z. tuberculatus were not shown to be able to distinguish reliably between the two species. The relevance of these findings to current theories about mechanisms of speciation is discussed.

Both major histocompatibility genes (MHC) and infection have been shown to influence urinary odours in mice, and mice may use MHC-associated odours to detect kin for the purpose of choosing communal nesting partners, or to avoid mating with close relatives. Additionally, mice may use infection-related odours to avoid mating with sick individuals or those genetically susceptible to infection. I tested the above theories using urine as the source of odour. In a series of odour preference experiments, employing two MHC-congenic strains of mice (B10 and B10.Q), I tested the proposition that females prefer MHC-similar female odours when choosing female relatives as nesting partners, and that females prefer MHC-disparate male odours for the purpose of disassoratative mating. I found that females did not display a preference for MHC-similar female odours or MHC-disparate male odours. However, when B10.Q male urine donors were infected with 100 L3 larvae of Heligmosomoides polygyrus (Nematoda), both strains of female displayed a significant preference for the odours of uninfected B10 males. To determine whether female odour preference for uninfected males extended to actual mate choice, I subsequently examined female mate choice in a controlled setting. Using CD-1 outbred mice, I found that females preferred to mate with uninfected males over males subclinically infected with 200 L3 of H. polygyrus , as evidenced by first ejaculation preferences. In this experiment, males were tethered, and as such, male dominance interactions were prevented. Thus, in the final experiment, to assess whether male dominance interactions influenced female mate choice, in addition to infection, I tested female mate choice in a seminatural setting, which allowed for social interactions to occur. In this study, paternity was ascertained through DNA analysis and the resulting data indicated that neither male dominance status nor infection had a substantial impact on fema / Overall, the data do not support the theory that MHC-based preferences occur through urinary odours. However, the results do substantiate previous findings regarding female preferences for the odours of uninfected males. Furthermore, data from the controlled mate choice assay indicate that female odour preference for uninfected males extends to actual mate choice. Conversely, in the seminatural setting neither dominance nor infection prevailed as factors driving female mate choice. I suggest that this may be a consequence of the structural complexity of my arenas.

This study explores the morphology and electrical behavior of breeding weakly electric fish. Wave-type electric fish communicate by means of a continuous oscillatory electric signal produced by an electric organ. The electric organ discharges at frequencies which are sexually dimorphic in many species of electric fish. This dimorphism is thought to be attributed to female mate choice, although to date, there is no evidence for mate choice or intrasexual competition to have driven the evolution of this signaling dimorphism in wave-type electric fish. Here, I have tracked changes in body shape and electric organ discharge (EOD) frequency of A. leptorhynchus throughout a breeding conditioning period. I find that only females alter the shape of their bodies, presumably to account for increasing egg mass, during the breeding conditioning period. Throughout this period, both females and males do not alter their EOD frequencies significantly. Gravid females were used in an unforced preference test, where they were presented with two live, male A. leptorhynchus. Female preference was indicated by a passage of the female into one of the two male compartments. I find that females show a preference for higher EOD frequency males, while no preference is shown for longer, heavier or larger-amplitude males. Further investigations are needed to dissociate the role of EOD frequency from potentially correlated male traits, such as rate and type of modulations of EOD frequency. The finding of this study that female A. leptorhynchus prefer males of higher EOD frequency establishes wave-type weakly electric fish as a promising model system for the study of the evolution and the sensory mechanisms of female choice.

Thesis (Ph. D.)--Oregon State University, 1989. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / 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 January 31, 2008) Vita. Includes bibliographical references.

Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Includes bibliographic references.

Thesis (M.A.)--University of North Carolina Wilmington, 2008. / Title from PDF title page (viewed September 22, 2008 ) Includes bibliographical references ( p. 41-44)

Title from title page of PDF (University of Missouri--St. Louis, viewed February 16, 2010). Includes bibliographical references.