Dissertations and Theses

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    Painting Wings - Evidence for a Role of Ca$^2$$^+$ in Butterfly Wing Phenotypic Plasticity
    ([Bloomington, Ind.] : Indiana University, 2022) Duro, Eduardo; Tracey, W. Daniel
    Wing patterns in butterflies serve several functions such as mimicry, sexual dimorphism, camouflage, and temperature regulation. Based on temperature adaptations by butterflies involving change in brightness and calcium mediated temperature responses. Here, we investigate the role of calcium in mediating the expression of light and dark scales. Through utilization of the butterfly Vanessa cardui as a model, I investigated how fluctuations in cytosolic calcium levels can potentially influence the development of wing brightness. Specimen brightness was manipulated with tungstate and thapsigargin injections. Tungstate has been shown to modify butterfly wing patterns but its mechanism of action has yet to be identified. Thapsigargin is a well-studied drug known to result in increases of cytosolic calcium similar to that of natural heat responses. Through utilization of these compounds, my hope was to reach a better understanding of the specific ways in which wing patterns are regulated by calcium. The specimens manipulated with pharmacological injections of thapsigargin showed an increase in the number of light scales within the injected area. Alternatively, specimens injected with tungstate showed a larger proportion of dark scales. Overall, findings suggest that calcium potentially plays a significant role in organizing wing pattern development.
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    Diurnal Variation in Minimal Thermal Conductance of the White-Footed Mouse (Peromyscus leucopus), the Golden Hamster (Mesocricetus auratus), and the Eastern Woodrat (Neotoma floridana)
    (1988-04) Stewart, Craig A.
    Minimal thermal conductance (MTC) has been used as a measure of the minimal rate heat loss from endotherms at low temperatures. An analysis of previously published data led to the suggestion of diurnal variation in MTC. However, the use of MTC has been debated on the grounds that it results from an incorrect and overly simplistic representation of the thermal exchange of small mammals. In this report, MTC is developed as a parameter in a linear, lumped-parameter model of the energy exchange of a small mammal at low ambient temperatures in a metabolism measurement chamber.