Theses and Dissertations from UMD
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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item Soldier neotenics of Zootermopsis nevadensis (Hagen) and Archotermopsis sp. (Isoptera: Termopsidae): Morphology, Development, Behavior, and Evolution(2009) Johnson, Susan Elaine; Thorne, Barbara L; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)I: The relictual reproductive soldier neotenics of primitive Termopsid termites may offer insights into the evolution of eusociality and sterile castes in termites. II: Soldiers and helpers in a new Thai species of Archotermopsis do not display unusually complete gonad development. The first neotenic pair ever reported for this genus is described. III: Morphological differences between soldiers and soldier neotenics in the head and gonads are quantified in Z. nevadensis. There is not necessarily a clear delineation in morphology between soldiers and soldier neotenics. IV: Colony age and size do not significantly influence the differentiation or survival of male replacement reproductives in colonies of Z. nevadensis. Soldier neotenics' development is not significantly influenced by the presence of normal soldiers. V: Soldier neotenics and related female neotenics tend to have greater initial survival after interactions with colonies with only normal neotenics. Mostly helpers are aggressors, never soldier neotenics or neotenics.Item COMPARATIVE STUDIES ON THE STRUCTURE OF THE EARS OF DEEP-SEA FISHES(2009) Deng, Xiaohong; Popper, Arthur N; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Many deep-sea fishes have sensory adaptations for living at great depths with very limited light. While such adaptations are best known in the visual system, it is likely that there are also adaptations in the auditory system that enable deep-sea fishes to use the "auditory scene." However, there are few data on the inner ear of deep-sea fishes. The purpose of this study was to add to those data. Since deep-sea fishes are rarely taken alive, this study was done through comparative anatomical investigations. Three families were chosen from two major deep-sea fish fauna: benthopelagic and mesopelagic. In Antimora rostrata (family Moridae, deep-sea cods), the inner ear structure and its coupling to the swim bladder were analyzed and compared with similar systems found in shallow-water fishes. Part of the membrane labyrinth is thick and rigid. The elaborate structure of the saccular epithelium and the close contact between the ear and swim bladder suggests enhanced hearing sensitivity. In the family Melamphaidae (bigscales and ridgeheads), five species from three genera show broad interspecific variation in the saccular otolith shapes, including having a long otolithic "stalk" in two genera. The presence of this "stalk" corresponds with a gradual change in the saccular maculae. A special type of ciliary bundle on the saccule may have enhanced sensitivity to bundle displacements. Ears were compared between six species of Macrouridae (grenadiers and rattails) that live at different depths. The saccule/lagena size ratio seems to increase with depth, especially between a mesopelagic and a benthopelagic species in the genus Nezumia, in which the benthopelagic species has an enlarged saccule associated with sound production. These findings support the hypothesis that some deep-sea fishes have evolved specializations for inner ear function. While it is not possible to test hearing in deep-sea fishes, the various adaptations found suggest that at least some such species have evolved specialized structures to enable them to use sound in the deep-sea. Some features in the ears of deep-sea fishes that have never been seen in the ears of other vertebrates, which further reveals the structural diversity of fish inner ears in general.Item Allometric comparison of brain structure volumes in three species of bowerbird: satin bowerbirds (Ptilonorhynchus violaceus), spotted bowerbirds (Chlamydera maculata), and green catbirds (Ailuroedus crassirostris)(2005-08-03) Bentz, Shannon Carson; Brauth, Steven E; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In three species of Australian bowerbirds the volumes of several brain structures were determined based on areal measurements of fixed tissue. Allometric comparisons, i.e., those that take into account the gross interspecies and intersexual differences in body mass and overall size, were made among these three species. Sexual dimorphisms were detected in the vocal control nuclei of each species. Most intriguingly, a putatively novel nucleus in the dorsal hyperstriatum of all three species has been identified. These findings are discussed in a functional context, in which the bower-building habits of these three species of bowerbird are considered.