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 The Effects of Tryptophan and Probiotic Treatment on Behavior and Production Parameters of Laying Hens(2021) Bonilla Carrero, Paola Ivette; Dennis, Rachel L; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Dietary supplementation can impact behavior expression through microorganism’s activity in the gut microbiome and influence productivity in animal husbandry. Adding supplements to production animals’ diet can impact behaviors and productivity via gut-brain axis activity. We investigated the effects of either probiotic or antibiotic supplementation in addition to the effects of additional tryptophan (Trp) on overall behavior and production parameters. White Leghorn chickens (n=12) were supplemented with six dietary treatments in a 2 x 3 factorial design: probiotics (1 x 109 CFU/L) or the antibiotic erythromycin (125 mg/L) in combination with either normal (0.16%) or high (0.48%) Trp in drinking water. Results indicate that probiotics with tryptophan increased locomotion (P = 0.04), social (P = 0.04), and eating behavior (P = 0.02). Antibiotics with tryptophan increased fat pad (P = 0.04) and heart weight (P = 0.04). Supplementation affected behavioral expression of normal, comfort, and pecking behavior, potentially impacted by metabolic competition at the level of the gut microbiome.Item The alarm-defense system of Cimex lectularius and its implications for pest management(2015) Ulrich, Kevin Richard; Thorne, Barbara L; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In this dissertation, I focus on the alarm-defense system of the common bed bug, Cimex lectularius, its effectiveness against pathogen attacks, and its role as a mechanism of communication for conspecifics. This dual role of an alarm-defense system is efficient and effective considering that the two functions are typically required simultaneously in times of danger; the same substance should serve both purposes. First, I surveyed the most common types of commercial bed bug treatments to determine long-term efficacy. Regardless of the treatment, chemical or heat, retreatments for bed bug infestations were required. After 3 years, 20.8% of housing units receiving a chemical treatment required additional treatments; 9.5% of units receiving heat treatments required a retreatment during the same period. Multifamily units required retreatments significantly more than all other housing types. Given these findings that emphasize the necessity for a multifaceted IPM program, I investigated whether the entomopathogenic fungus, Metarhizium anisopliae, could be used to control bed bugs. Feeding experiments demonstrated that bed bugs were innately susceptible to this fungus. However, regardless of whether bed bugs were sprayed with a fungal solution or contacted a treated surface, only at 98% humidity was mortality high. In addition, the two major aldehydes (E)-2-hexenal and (E)-2-octenal emitted as defensive secretions by bed bugs inhibited the in vitro growth of an isolate of M. anisopliae. The ability to accurately and quickly detect new infestations is a critical element to an IPM-based strategy. This detection requires an understanding of attraction behavior and cues. I show through use of video-tracking software, (E)-2-hexenal and (E)-2-octenal attract adult bed bugs. Behavioral assays determined both males and females were attracted to 0.04 ug of an aldehyde blend for up to two hours after initial treatment of filter paper disks. Results suggest that these bed bug secretions may be candidates for lures and monitors. Taken together, this research describes the chemical ecology of bed bugs, providing insight into relevant signaling and defensive behavior, which has direct implications on pest management practices.Item Dispersal and Population Ecology of the Red-backed Salamander (Plethodon cinereus)(2015) Hesed, Kyle Miller; Wilkinson, Gerald S; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Terrestrial salamanders are major components of ecosystems in eastern North America. One species, the Red-backed Salamander (Plethodon cinereus), may be the most abundant vertebrate throughout its range. Red-backed Salamanders are commonly monitored as indicators of ecosystem health and to assess the effects of forest management practices. In order to address poorly understood aspects of the ecology of Red-backed Salamanders, I conducted a 4-y mark-recapture study of a population in Maryland, resulting in 2,745 records of 752 marked salamanders, along with a complementary genetic analysis of six microsatellite loci. I estimated growth rates and age at sexual maturity using a hierarchical Bayesian model fitted by mark-recapture measurements, then measured home range size and seasonal and annual movement distances by immatures and adults, before and after the experimental removal of 98 conspecifics. Males grow and mature more slowly than females, despite reaching slightly larger asymptotic sizes; they may also face greater competition for space: adult males occupy the largest home ranges and show the largest increase in home range size after the removal of conspecifics. The largest between-year movements were made by individuals as they transitioned from immaturity to maturity. Using mark-recapture population models, I found that estimates of survival, detection, and abundance varied temporally along with the age and sex of the individuals present, both within and among seasons. Encounter probability varied among weekly sampling occasions, and models with separate parameters for each sex were strongly preferred. Survival was approximately the same over winters and summers, and lower for males than for females; this may be an artifact of sex-biased dispersal, as the majority of encountered immature individuals were estimated to be males, with models indicating a pulse of emigration in the fall and an influx of immature males onto the study site in the spring. An FST randomization test of multilocus genotypes showed a significant male bias in dispersal. Of salamanders captured repeatedly as both immatures and adults, males moved significantly farther before maturity than females did. Together, these results provide a comprehensive assessment of sex-biased dispersal at fine spatial and temporal scales in a terrestrial ectothermic vertebrate.Item COOPERATION AND SOCIAL BONDS IN COMMON VAMPIRE BATS(2015) Carter, Gerald; Wilkinson, Gerald S; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Regurgitated food sharing among vampire bats is a classic textbook example of reciprocity ("reciprocal altruism"). But many authors have contested both the notion that reciprocity explains vampire bat food-sharing and the importance of reciprocity more generally. In Chapter 1, I review the literature on evolutionary explanations of cooperation. I show why reciprocity was once considered important but is now considered rare: overly literal translations of game theory strategies have resulted in problems for both defining and testing reciprocity. In Chapter 2, I examine the relative roles of social predictors of food-sharing decisions by common vampire bats (Desmodus rotundus) under controlled conditions of mixed relatedness and equal familiarity by fasting 20 individuals in 48 trials over two years. The food-sharing network was consistent, symmetrical, and correlated with mutual allogrooming. Non- kin food-sharing patterns were not consistent with harassment or byproduct explanations. I next attempted to manipulate food-sharing decisions in two ways. In Chapter 3, I administered intranasal oxytocin to test for effects on allogrooming and food sharing. I observed that inhaled oxytocin slightly increased the magnitude of food donations within dyads, and the amount of female allogrooming within and across all partners, without increasing number of partners. In Chapter 4, I assessed contingency of food-sharing in 7 female dyads (including four pairs of mother and adult daughters) with prior histories of sharing. To test for evidence of partner switching, I measured dyadic levels of food sharing before and after a treatment period where I prevented dyadic sharing (each bat could only be fed by others). A bat's sharing network size predicted how much food it received in the experiment. When primary donors were excluded, subjects did not compensate with donations from other partners. Yet, food-sharing bonds appeared unaffected by the non-sharing treatment. In particular, close maternal kin were clearly not enforcing cooperation using strict contingency. I argue that any contingencies within such bonds are likely to involve multiple services and long timescales, making them difficult to detect. Simple and dyadic `tit-for-tat' models are unlikely to predict cooperative decisions by vampire bats or other species with stable, mixed kinship, social bonds.Item Felis: Identifying Opportunities for Change(2014) Lucarelli, Theresa Marie; Rockcastle, Garth C; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Although many cats are loved and well cared for by enthusiastic and compassionate owners, tens of millions of cats suffer from human neglect and ignorance, leading to low adoption rates and high euthanasia numbers across the world. Of all cats that enter shelters, 70 percent are euthanized. In addition to the millions of cats that reside in shelters, there are approximately 50 million stray and feral cats, compared to 76 million pet cats in the United States. This thesis serves to identify, understand, and analyze the diverse roles cats play in the lives of humans and general ecological well-being. It is necessary to critically and creatively analyze the human relationship to cats throughout history, as well as how contemporary architecture and urbanism has and is continuing to do cats a disservice through an inattention to and neglect of their needs. The central question I will seek to address is: How can accommodations be designed to provide spaces that promote a happy and healthy environment for cats and for humans and enhance the relationship between humans and cats?Item The development and testing of three techniques for attaching solar-powered GSM satellite transmitters on surf scoters(2014) McBride, Kevin Mark; Ottinger, Mary Ann; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Implanted satellite transmitters are used in seaducks to track migration routes, breeding, and wintering grounds. However, high mortality rates, handling stress, and inadequate small-scale location data necessitates the use of external transmitters. Three external transmitter attachment techniques were tested, including a Teflon tape harness, sutures to anchor the transmitter through the dorsal vertebral processes, or a 3D individually customized silicon harness on 12 surf scoters (Melanitta perspicillata). Body weight, serum and hematology chemistry, behavioral time budgets, and dive performance were used as measures of impact for each transmitter. Global System for Mobile Communications (GSM) transmitter performance was evaluated for accuracy, precision, and battery performance for use in seabirds. All methods had transient effects on weight, serum chemistry, immune response (sutured transmitters), and increased bottom and total dive times. Teflon harnesses impacted behavior. Silicon harnesses had the least deleterious effects compared to other treatments. Accordingly, we recommend silicon harnesses for deploying external transmitters in wild seaducks.Item In-air and Underwater Hearing of Diving Birds(2014) Therrien, Sara Crowell; Carr, Catherine E; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In-air and underwater auditory thresholds were measured in diving bird species, using behavioral and electrophysiological techniques. In the first set of experiments, the auditory brainstem response (ABR) was used to compare in-air auditory sensitivity across ten species of diving birds. The average audiogram obtained for each species followed the U-shape typical of birds and many other animals. All species tested shared a common region of greatest sensitivity, from 1000 to 3000 Hz. The audiograms differed significantly across species. Thresholds of all duck species tested were more similar to each other than to the two non-duck species tested. The red-throated loon (Gavia stellata) and northern gannet (Morus bassanus) exhibited the highest thresholds while the lowest thresholds were observed in the duck species, specifically the lesser scaup (Aythya affinis) and ruddy duck (Oxyura jamaicensis). In the second set of experiments, both the ABR and psychoacoustics were used to measure in-air auditory sensitivity in one species of diving duck, the lesser scaup. Both approaches yielded audiograms with similar U-shapes and regions of greatest sensitivity (2000-3000 Hz). However, ABR thresholds were higher than psychoacoustic thresholds at all frequencies. This difference was smallest at the highest frequency tested using both methods (5,700 Hz) and greatest at 1,000 Hz, where the ABR threshold was 26.8 dB higher than the behavioral measure of threshold. In the third set of experiments, psychoacoustic techniques were used to measure in-air and underwater sensitivity in one species of sea duck, the long-tailed duck (Clangula hyemalis). Underwater auditory thresholds were measured for the first time in any diving bird species. Long-tailed duck in-air sensitivity was greatest at 2000 Hz. The ducks responded reliably to sound stimuli underwater, and correctly responded to high intensity stimuli (greater than 117 dB re 1 μPa) with over 80% accuracy at frequencies between 0.5 kHz and 2.86 kHz. The large differences in diving behavior and physiology across bird orders suggest these studies should be extended to other diving bird species in order to understand how well birds hear underwater. These first measurements highlight the need for further investigation into underwater hearing in diving birds, in order to understand underwater hearing mechanisms and begin to develop hypotheses as to how the introduction of man-made noise sources into the aquatic environment may impact these species.Item Avian/Human Architecture(2013) Atalig, Jane Rase; Ambrose, Michael A; Rockcastle, Garth; Architecture; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Belonging to the Commonwealth of the Northern Mariana Islands (CNMI), Rota, the southernmost island in the Northern Mariana Island archipelago, is home to a naturally protected avian sanctuary that hosts critically endangered species of birds found nowhere else in the world. The island's unique environment has attracted the interest of academic institutions and international visitors focused on learning more about the island's ecosystem. While attempting to address the CNMI's tourism issues, the most recent tourism master plan for the islands, NMI Tourism Master Plan 2012-2016, fails to recognize Rota as a major candidate for economic growth. This thesis proposes a solution to both address tourism issues as well as educate locals and visitors of the importance of ecological sustainability through critical and creative exploration of the interaction between avian and human architecture.Item Candidates for the Redemption Machine(2013) Gannon, Shaun Patrick; Collier, Michael; Creative Writing; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This collection takes the concept of the "stunted individual" from grotesque fiction and applies it to surrealist prose poetry, where only traces of standard logic can be found; through this, the contrast between impossible events and innately human behavior becomes exaggerated. The melding of these forms forces the struggling individuals in these poems to represent humanity, where it is found wanting, despite artificial hope.Item The effect of sunlight on decoration placement and mating success in male satin bowerbirds(2012) Larned, Archer Freni; Borgia, Gerald; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Males of some bird species choose sunlit display sites to enhance their visual signal. Satin bowerbird (Ptilonorhynchus violaceus) males place colored decorations on their bower platform as part of their courtship display. Little is known about how illumination affects the attractiveness of decorations. We analyzed photographs to quantify the amount of direct illumination on the bower and the number of blue decorations in sunlight. We found that the proportion of sunlight on the entire bower platform during peak female visitation periods is correlated with male mating success. The North platform, where decorations are concentrated, was proportionately more illuminated than the South platform. Males placed decorations in more sunlit areas on the platform and returned moved blue decorations to their original locations, suggesting that males actively place blue decorations in sunlit areas. This is the first study to demonstrate that greater illumination in off-body displays may be important for attracting females.