Biological Sciences Doctoral Work

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The Distribution and Habitat Use of North Dakota Bats
(North Dakota State University, 2014) Barnhart, Paul Roy
Prior to 2009, a comprehensive statewide survey of occurrence and distribution of bats in North Dakota had not been conducted. From 2009 to 2012, mist netting, radio telemetry, and acoustic monitoring were conducted to document species presence and habitat associations across North Dakota. We surveyed multiple sites at 17 locations, captured a total of 309 bats, documented habitat associations, and identified roosting sites. Data was then used to: 1) build habitat suitability maps (also called species distribution maps or SDMs) for each species in the state, 2) examine the environmental and climatic variables that influence bat habitat use along the periphery of their distribution, 3) assess the effect of sampling technique on habitat suitability models, and 4) determine if North Dakota's badlands region contains overwintering bat populations that may be susceptible to white nose syndrome, an emerging fungal disease of hibernating bats. We confirmed the presence of 11 species in the state and found that five species were present in areas outside their ND IUCN distribution. Maximum-entropy modeling showed that temperature was the most important variable for SDM production. We found that sampling technique (physical capture vs. acoustic detection) led to pronounced differences in habitat suitability maps for some species (33.9% overlap; Myotis septentrionalis) while models from other species were highly similar (80.4% overlap; Myotis lucifugus). Our findings show that acoustic detection results in better SDMs for Myotis spp. while physical capture was best for Eptesicus fuscus and Lasionycteris noctivagans. During the winter, we positively identified four species based on both acoustic detection and physical capture: E. fuscus, Myotis evotis, Myotis ciliolabrum, and Corynorhinus townsendii. Based on known and potential hibernacula locations, we produced a habitat suitability map that was successfully used to locate additional potential hibernacula. We also recorded temperature in confirmed and potential hibernacula, finding that temperatures were within the optimum range of fungal growth. The information gathered from these studies will be used to develop the first statewide conservation action plan for North Dakota bats. Also, the habitat suitability maps produced will be used by managers to target areas of high priority for conservation of bat communities.
Evidence of Climate Niche Creation in the Northern Great Plains: The History of Invasion, Population Genetics, Competitive Effect, and Long-Term Trends of Invasive Poa Pratensis L.
(North Dakota State University, 2016) Dennhardt, Lauren Alexsandra
Understanding the mechanisms of invasion is critical in order to control an invasive species. Poa pratensis L. (Kentucky bluegrass) is an invasive species that has been present in the northern Great Plains (NGP) for over 100 years, but has become a dominant species in the mixed grass region recently. My dissertation seeks to answer one critical question—why has P. pratensis become such a successful invasive species in the NGP? I first asked if the invasion was caused by adaptation and/or propagule pressure. I screened the genetic fingerprint of invasive P. pratensis in the NGP along with measuring the genomic content of wild plants and compared them to common cultivars. I found virtually no overlap between lawn cultivars and invasive P. pratensis populations. This was further supported by a narrow range of genomic content in wild individuals compared to the lawn cultivars. I also found no evidence of geographical patterning which is consistent with the hypothesis that local adaptation is not pervasive in P. pratensis. I then asked whether P. pratensis was a strong competitor compared to dominant plant species native to the tallgrass prairie. I studied competitive effect between Poa pratensis, Nassella viridula, Pascopyrum smithii, and Bouteloua gracilis through a species-pair competition experiment. Based on the relative interaction indices, P. smithii and P. pratensis were competitive against B. gracilis, and P. smithii was competitive against N. viridula. Additionally, P. pratensis was facilitated by all three species in the experiment. This study indicates that P. pratensis may be somewhat competitive. Finally, I asked whether the increase in the frequency of P. pratensis in the NGP may be attributed to environmental factors. In order to understand long-term correlations between P. pratensis invasion and environmental variables, I resampled plots that were previously sampled for species composition in 1978, 1979, and 1999. I found that P. pratensis levels did increase across plots and was corrrelated with higher levels of precipitation. My research indicates that increased precipitation in the NGP as a result of climate change is correlated with P. pratensis invasion in the NGP.
Population Dynamics and Management Implications for American White Pelicans (Pelecanus Erythrorhynchos) Breeding at Marsh Lake, Lac Qui Parle Wildlife Management Area, Minnesota
(North Dakota State University, 2016) DiMatteo, Jon J.
The American white pelican (Pelecanus erythrorhynchos) is a prominent breeding bird in Minnesota, but little information has been available on their production, population dynamics, growth and development, or demographic characteristics. I examined life-history traits of American white pelicans nesting colonially at Marsh Lake, Lac qui Parle Wildlife Management Area, Minnesota. Marsh Lake is an impounded river floodplain lake on the Upper Minnesota River that holds the largest American white pelican breeding colony in Minnesota (and one of the largest American white pelican breeding colonies in North America). An analysis of colony population levels and spring streamflow data indicated that more than 84% of the variation in the number of near-fledged chicks produced per nest was related to mean daily discharge during April. In years when high water floods preferred low-elevation nesting habitat on islands in the middle of the lake, American white pelicans are forced to establish nests on high-elevation sites that are closer to the mainland. The proximity to the mainland leaves the high-elevation sites accessible to mainland mammalian predators, and production rates decline. An examination of size at hatch and growth of American white pelican chicks showed little variation in initial size and growth rates between years. However, substantial variation in initial size and growth rates were detected within season depending on the timing of hatch. Initial mass did not vary throughout the nesting season, but initial tarsus and wing length were shorter in chicks hatched later in the season. However, growth rates for mass, tarsus, and wing were faster for late-hatched chicks, potentially allowing late-hatched chicks to fledge at an earlier age. An analysis of demographic characteristics of American white pelicans nesting at Marsh Lake indicated timing of nest initiation was not related to age or body condition of adults. However, nests were initiated earlier on the preferred nesting island at Marsh Lake. Although some individuals may nest at an earlier age, the estimated age of maturation for American white pelicans nesting at Marsh Lake suggests they are unlikely to begin nesting until they are at least five years old.
Short- and Long-Term Effects of Environmental Variability on the Ecophysiology of a Solitary Bee
(North Dakota State University, 2022) Earls, Kayla
Environments can vary across seasons. One characteristic of spring in temperate regions is fluctuations in temperature. Sudden bouts of low temperature can have lasting effects on ectotherms that rely on ambient temperature. For developing insects, being unable to avoid or manage these low temperatures puts them further at risk. For example, Megachile rotundata undergo active development in the spring. Exposure to low temperatures as pupae for short periods does not decrease survival but does affect adult morphology. Pollination services may also be affected if temperatures are too low to promote flight in adults. The overall question is what are the short- and long-term physiological effects of temperature in pupae and adults? The first objective of this dissertation is to investigate the long-term effects of low temperature stress by measuring flight performance, reproductive output, and offspring characteristics. After receiving a constant low temperature for a week, females were less likely to nest and changed their offspring investment. Additionally, offspring of bees exposed to fluctuating low temperature stress were more likely to enter diapause despite being early in the season. The second objective was to test if oxygen consumption across temperatures generated a thermal performance curve as a short-term effect in M. rotundata pupae. Results indicate that oxygen consumption scales non-linearly like a thermal performance curve; however, the negative slope at high temperatures was not observed. The third objective was to determine how microclimate conditions affect flight initiation in M. rotundata adults. Two different activity boxes were designed to measure environmental variables and to manipulate cavity temperature. The first activity box measured several environmental variables and showed that even at very close proximities, M. rotundata experience different temperature conditions. In the other activity box design, internal cavity temperature was manipulated to increase early in the morning. Results show that increasing the cavity temperature promoted earlier flight and at lower ambient temperatures. This dissertation shows that the life stage an insect experiences a thermal stress can affect short- and long-term effects on physiology and life history in M. rotundata.
Social and Acoustic Behavior of the Leaf-Roosting Bat Thyroptera Tricolor
(North Dakota State University, 2015) Montero, Bianca Karina
The limited availability of refuges may represent an important factor promoting the evolution of sociality, particularly in bats. Spix’s disc-winged bats (Thyroptera tricolor) show highly specialized morphological adaptations that enable individuals to roost inside furled musoid leaves. This roosting ecology presents major challenges, as leaves rapidly unfurl, forcing bats to locate new roosts on a daily basis. Despite the reliance of T. tricolor on such ephemeral roosting resources, bats form stable group associations. The purpose of this study was to characterize the behavioral patterns associated with assessing roosts and any accompanying communication strategies of Spix’s disc winged bats. In the first chapter, I used video and acoustic monitoring to test the hypotheses that finding a high quality roost involves the regular assessment of leaf suitability within a group’s rooting range and that acoustic signals facilitate group interactions during nightly activity. The second chapter examines the patterns of geographic variation in two contact calls regularly emitted by T. tricolor. I evaluate the congruence of geographic variation in the acoustic features of contact calls with genetic differentiation of two populations in Costa Rica separated by a geographic barrier. In the third chapter, using an automated telemetry system, I examined the nocturnal movement patterns of all group members within the limits of the roosting range. I determined that bats regularly monitor furled leaves within their roosting range, during which they emit a number of distinct social calls. Among the acoustic signals produced by these bats, two calls are particularly common near furled leaves. When examining the relationship between genetic distance and acoustic divergence of these two contact calls I found discordant patterns of variation, suggesting the presence of distinct modes of vocal transmission within populations. The continuous assessment of movement patterns during foraging bouts provided evidence that in general, bats remain within close proximity of a group’s roosting range and the occurrence of dyadic encounters during the course of the night. This study contributes to our understanding of the behavioral strategies used by free-ranging bats providing valuable insight into the role of shelter stability in the evolution of the T. tricolor social system.
Using a Cross-Cutting Theoretical Framework to Explore Difficulties Learning Human Anatomy and Physiology
(North Dakota State University, 2020) Slominski, Tara Nicole
Across the United States, Human Anatomy and Physiology (HA&P) courses typically have some of the highest withdrawal and failure rates on college campuses. These high enrollment course typically serve as gate-keepers for those individuals with aspirations of entering the medical field. In light of the growing national shortage of healthcare professionals, there is a pressing need to improve the state of HA&P education at a national scale. The goal of this dissertation is to understand why undergraduate students struggle to succeed in HA&P courses. I leveraged multiple frameworks from biology education research, physics education research, and cognitive psychology to understand the source of student difficulty in HA&P. I used a mixed-methods approach to unpack how students reason about the complex phenomena covered in HA&P classes. The data presented here suggest student difficulties in HA&P are not the product of a culmination of individual conceptual difficulties. Rather, this work suggests students have difficulty reasoning with the many complex systems that are at the heart of HA&P curriculum. Students appear to frame these complex systems in a manner that activates reasoning strategies that are often in conflict with course goals. The findings from this work advocate for a dynamic view of student cognition that recognizes the implications of context features on student reasoning of complex systems.

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Browsing Biological Sciences Doctoral Work by browse.metadata.program "Biological Sciences"