RSS 1.0Biological Sciences
For Marine Biology, see the Marine Sciences collection.
Recent Submissions
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Human-polar bear interactions on the northern coast of AlaskaPolar bears (Ursus maritimus) are sea ice-dependent marine mammals that, due to reductions in sea ice extent in the southern Beaufort Sea, are increasing their time spent on shore. Simultaneously, the anthropogenic footprint on the northern coast of Alaska is growing. As a result, human-polar bear interactions in this region are increasing. These interactions have the potential to be dangerous for humans, harmful to polar bears, and, therefore, require deliberate management. In this thesis, I examined two study systems that lacked the depth of knowledge necessary to craft defensible management plans. My research generated information regarding human-polar bear interactions that could be used to shape policy in the Arctic. In Chapter 1, I explored a dataset that documented human-polar bear interactions at a popular polar bear viewing area in Kaktovik, Alaska. My objectives were to determine what factors influence 1) polar bear displacement (temporary or permanent) from the viewing area and 2) human response (assertive or neutral) to an approaching bear. Using logistic regression, I determined that permanent polar bear displacement was more likely later in the observation season and when the bear's initial reaction to a human approach occurred as a greater distance. I also found that humans were more likely to act assertively towards a bear when food resources (i.e., whale bone pile) in the area were depleted. These behavioral patterns indicate that human and bear tolerance change over time and in relation to resource availability. In Chapter 2, I conducted the first systematic evaluation of polar bear behavioral response to overhead aircraft traffic. I conducted field sampling in a fixed-wing aircraft and observed polar bear response at varying altitudes. My goal was to intentionally elicit a behavioral response that, under the guidelines in the Marine Mammal Protection Act, would be considered biologically significant. My objectives were then to 1) predict when a polar bear would exhibit a biologically significant behavioral response and 2) estimate the probability of an aircraft eliciting a biologically significant response at different altitudes above the animal. Using linear regression and a hierarchical Bayesian approach, I found that bears were most likely to exhibit a biologically significant response when they were active prior to sampling, located on the mainland coast, and the aircraft approach altitude was less than 457m (1500ft). Furthermore, I found that the probability of eliciting a biologically significant behavioral response at a flight altitude of 30m (100ft) was 21.31% for an inactive bear on a barrier island and 61.46% for an active bear on the mainland coast. Together, these research efforts address pressing knowledge gaps related to polar bear behavior on the northern coast of Alaska. Information generated from this project can be used to inform management and reduce disturbance for polar bears in a changing Arctic.
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Soundscapes on the Arctic Coastal Plain: assessing sound disturbance and the auditory sensitivity of caribou (Rangifer tarandus)The Arctic Coastal Plain of Alaska is a region on traditional Inupiat land that supports millions of migratory birds and over half a million caribou (Rangifer tarandus) at the most critical time in their life-histories. They are an important part of seasonal subsistence activities for the surrounding rural Indigenous communities. Therefore, conservation efforts that support this ecosystem also bolster food security in the region. Monitoring this system has increasingly become a necessary and prudent task as the landscape evolves under the pressures of resource extraction and climate change. To date, limited research has been conducted on the sounds present in this environment (i.e., 'soundscape'). Monitoring sounds may help reveal the impact of these stressors and ecosystem-wide changes. There is also a need for researchers to evaluate what portion of the soundscape wildlife can actually hear, so we can better understand how soundscape change might affect them. I conducted two studies that apply soundscape monitoring and acoustic perception to the landscape and wildlife of the Arctic Coastal Plain. First, I evaluated the hearing thresholds of domestic Rangifer tarandus (reindeer) at the Large Animal Research Station at the University of Alaska Fairbanks in 2019 in order to help infer what anthropogenic sounds wild caribou may be sensitive to. Using Brainstem Auditory Evoked Response methods, I found that a caribou's auditory system can detect all forms of anthropogenic sounds that they might encounter on the Arctic Coastal Plain, including low frequency sounds associated with oil and gas exploration. Specifically, I found they can detect sounds as low as 30 Hz with great sensitivity, expanding the known lower limit of their auditory capabilities. This means that caribou may detect sounds of seismic exploration, gravel mine blasting and other anthropogenic sounds associated with resource extraction at a great distance, and may be more affected by these sounds than previously thought. From May through August of 2019, I used acoustic recording units stationed in a random grid across the Arctic Coastal Plain to passively monitor the soundscape study region-wide sound characteristics and their impact on vocal wildlife. Anthropogenic sound (i.e., anthrophony) is a pervasive and often overlooked consequence of land-use change, and something that has been relatively understudied in northern Alaska. For my soundscape research, I modeled the spatial and temporal distribution of anthrophony and bird vocalizations (i.e., biophony) across developed (Oilfields surrounding Prudhoe Bay), and undeveloped (Arctic National Wildlife Refuge) areas of the Arctic Coastal Plain. Hourly detections of anthrophony were not associated strongly with infrastructure but tended to increase as the season went on. Birds were more likely to vocalize in hours when anthrophony was present, and this effect was the strongest in the early season, during migratory bird arrival and breeding. Anthrophony's effect on the soundscape may alter biological cues that vocal and non-vocal migrants use to assess habitat patches, and fitness consequences will vary by species. Further research is needed to assess how bird communities and caribou movement respond to anthrophony.
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Timing of flowering affects pollination and fruit set in Viburnum edule in boreal forests of AlaskaSpring flowering in Alaskan boreal forests is happening earlier on average; how this relates to the pollination of plants and their pollinator community is unknown. Highbush cranberry (Viburnum edule) is one of the first herbaceous understory plants to flower every year, and in years when it flowers early there are fewer other species in bloom compared to years when it flowers at a more average time. Highbush cranberry is also important as a subsistence food and many boreal animals consume these fruits as a regular part of their diet. The potential for change may lead to differences in the response of pollinators and plants under early season conditions which could alter resources for pollinators and impact fruit production. This research looks at the impact of flowering timing on pollen deposition on Viburnum edule, and the composition of the pollinator community visiting the available flowers. Using an experiment with flowers placed in boreal forest sites either at an early time or at a peak flowering time across two years, we found that early flowering highbush cranberry received fewer pollen grains than peak flowering highbush cranberry and were visited less. V. edule was primarily visited by syrphid flies, native bees, and muscoid flies. We also observed a lower total number of visitors, and a lower proportion of visitors that were bees during an early flowering time than at peak flowering time. Floral visitors were more abundant during the advanced flowering year than during an average flowering year. We do not currently think that pollen limitation is causing a reduction in fruit set of early flowering V. edule because at all flowering times observed, we found over 50% of flowers to have been presumed visited while less than half of flowers in an inflorescence form fruits on average. More information on boreal pollinators triggers for diapause break and floral visitation is necessary to make more reliable predictions of the future impacts of phenology shifts in flowering plants and insect pollinators.
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Applying third-generation sequencing to pathogen surveillance and mixed infection detectionOne Health is the concept of interconnected health between plants, animals, humans, microorganisms and the environments they live in. One Health issues surround many important viral pathogens, including influenza, SARS-CoV-2, and Ebola, that have likely come from zoonotic spillovers. Genomic epidemiology combines pathogen genomes with metadata to forecast, track, and prepare for future pathogens and pathogen variants that may cause epidemics. Genomic epidemiology has been used to detect and track viral variants that have the potential to escape vaccines for viruses like porcine circovirus type 2 (PCV2). PCV2 causes porcine circovirus associated diseases (PCVAD), which results in weight loss and death in pigs around the world. The correlation between PCVAD and mixed infections shows that disease severity is linked to the microbial community in a host. Metagenomics allows researchers to sequence samples and sort out the individual community member genomes by bioinformatic analyses, allowing the study of the host microbiome. In this thesis, I tested if long read nanopore sequencing can uncover PCV2 diversity and reliably detect co-infections. I also assessed the accuracy and efficiency of long read metagenomic assemblers as a potential method for detecting mixed infections. In my first chapter, I found that nanopore sequencing can be used to understand PCV2 diversity and detect co-infections. This evidence shows that nanopore sequencing is a viable alternative to Sanger sequencing for PCV2 surveillance. In my second chapter, I found Flye built the most complete and accurate genomes for bacterial community members and their plasmids. Throughout my thesis I have shown that nanopore sequencing is a viable solution for modern surveillance. The lower cost of nanopore sequencing may allow more specific pathogen and metagenomic surveillance in regions with high risk of zoonotic spillovers, which may allow early detection of epidemic causing pathogens.
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Seeing the forest through the trees: how site conditions mediate white and black spruce responses to climate in Interior AlaskaThe boreal forest provides essential ecosystem services and helps regulate global climate. With climate change occurring at a faster rate at high latitudes, including in the boreal forest biome, it is critical to understand how boreal forests are responding to these unprecedented changes. Despite much effort, uncertainty remains as to how boreal forest productivity has and will change with ongoing climate changes. Some of the uncertainty reflects the complex mosaic of regional climatic patterns, direct and indirect species-specific responses to regional climate, and heterogenous local site conditions that affect boreal forest productivity. I focused on the latter uncertainty: the potential role of topographic, edaphic, and biotic conditions in mediating the climate-growth responses of boreal tree species. My overarching goal was to quantify the radial growth response of black spruce (Picea mariana) and white spruce (Picea glauca), the two most common tree species in interior Alaska, to climate variability across a suite of site conditions to better understand the observed and predicted variation in climate driven productivity across a variable landscape. I employed a systematic sampling design to quantify the landscape-scale patterns in both environmental conditions and incremental annual growth of trees distributed across a 1.28 million-ha study area in Denali National Park and Preserve (and beyond in Chapter 4). I also used targeted sampling of carbon isotopes in tree rings to investigate potential drought stress. I found that near-surface permafrost, slope angle, and elevation strongly modified the magnitude, shape, and, in some cases, the direction of radial growth response of both species. For white spruce, the negative growth response to warm and dry summer conditions intensified in high competition stands and in areas receiving high potential solar radiation. During years with high cone and seed production, white spruce shifted its current year's carbon resources from radial growth to reproduction and showed signs of drought stress. I also observed differences between black and white spruce climate-growth responses, with near-surface permafrost driving their contrasting responses to June-July temperatures and with black spruce growth showing an overall more positive response to summer precipitation. These results demonstrate that local site and stand variables can force contrasting growth responses to similar climate conditions and help predict how future black and white spruce growth may play out with climate changes across a heterogeneous landscape. My results underscore the pivotal role of near surface permafrost in both the climate-growth responses and competitive dynamics of black and white spruce. Consequently, my results emphasize the importance of ongoing and predicted changes in the distribution and prevalence of permafrost for the future of the boreal forest.
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Snow as structural habitat for wolverines in a changing ArcticArctic snowpack provides critical wintertime habitat for animals to facilitate thermoregulation and avoid predators. Wolverines (Gulo gulo) are iconic among such animals, relying on snow burrows for resting sites and reproductive dens. Most of the knowledge regarding this mesocarnivore's association with snow, however, has so far originated in more southerly latitudes. In this dissertation, I investigated Arctic wolverines' behaviors associated with snow, focusing on how specific snow properties influence resting, habitat selection, and avoiding predators. Motivated by the paucity of published descriptions of wolverine resting burrows and reproductive dens on tundra, I first described terrain features and architecture of such sites. I found that resting burrows typically consist of a single tunnel leading to a resting chamber, sometimes associated with non-snow structure such as stream cutbanks and river shelf ice. By contrast, reproductive dens typically consist of longer tunnels associated with snowdrift-forming terrain. Second, I used GPS collar data from 21 adult wolverines, coupled with snowpack information at 10 meter pixel resolution, to evaluate wolverine habitat selection and movement response to snow depth, density, and melt status. I found that wolverines select deeper, denser snow, except when snow is melting, likely reflecting resting site use. Third, I developed a machine learning model to classify wolverine behaviors using tri-axial accelerometers based on direct observations of three captive wolverines, and applied this model to free-living wolverines in Arctic Alaska. I found that the model performs better when allowed to predict behaviors as "unknown," and that it accurately predicts resting, food handling, running, and scanning surroundings. Finally, based in part on this classification model, I evaluated the extent to which wolverines' use of snow burrows and surface beds for resting sites is influenced by thermoregulatory needs versus predation avoidance. I found evidence in support of both demands driving resting behavior; wolverines trade thermoregulation off against predation avoidance by resting on the snow surface on warm, sunny days, but use snow burrows on cold, dark days to meet both demands simultaneously. Collectively, this dissertation demonstrates the importance of Arctic snowpack to wolverines, a topic of increasing importance as the snow season shortens with climate change, and serves as a model for investigating behavioral processes associated with snow among other species.
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Drivers and mechanisms of migration in an Arctic caribou herdMigration is one of the world's great natural wonders and the scale of some migratory journeys is astounding. Yet migration is globally imperiled and effective conservation of the remaining migrations will require a thorough understanding of the drivers and mechanisms underlying how migrants complete such journeys. In this dissertation, I present three chapters that sought to better understand spring and autumn migration for the Western Arctic Herd, a population of barren-ground caribou (Rangifer tarandus) that complete some of the longest terrestrial migrations on the planet. In the first chapter, I applied and validated an analytical method to infer parturition events from GPS data with robust statistical confidence. In the second chapter, I examined the parturition events detected with these methods to better understand the drivers and mechanisms of spring migration because the calving grounds are the destination for pregnant females in spring. I quantified annual spatial patterns of calving and assessed what environmental factors influenced calving site selection by caribou through time. I found evidence of both memory and perception influencing spring migration, such that caribou use memory to return to an area of generally high-quality forage at the time of calving, and consequently adjust calving sites each year based on experienced conditions. In the third chapter, I sought to understand the environmental cues caribou respond to in deciding when to migrate in autumn. I found that decreasing temperatures and the timing of first snowfall events of the season had the greatest influence on migratory movements, but notably, caribou re-assessed decisions throughout the migration period as the conditions they experience changed. I also found that the cues caribou used are similar across individuals despite the herd being broadly dispersed in late summer, and the variability in migration timing observed each year is likely due to variability in environmental conditions experienced across the range. These findings pertaining to the drivers and mechanisms of migratory behavior, and broader aspects of movements by caribou, are highly relevant for conservation and management of the species across the circumpolar North. Moreover, the observation that caribou movement exhibits strong responses to particular climate phenomena, such as temperature and precipitation, have important implications for how caribou might respond as the climate of the Arctic continues to change.
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Rooted in environmental justice: phytogeography and ethnoecology of SerianthesSerianthes Benth. (Fabaceae) is one of the most endangered plant genera in the world, with 12 of the 18 species listed on the IUCN Red List of Threatened Species. Serianthes trees are culturally important to island communities of the Indo-Pacific region for canoes, boats, traditional houses, and medicine. Habitat loss and ecosystem degradation increased pressure on these trees, also threatening its Indigenous cosmology and traditional practices. This interdisciplinary study integrated genomic, biogeographic and ethnoecological approaches to develop appropriate policies that protect the Indigenous biocultural diversity of Serianthes. Phylogenomics of 401 nuclear exons and non-coding flanking regions using both a multi-species coalescent model and a partition gene tree analysis confirmed the monophyly of the genus and inferred the biogeography and phylogenetic relationships within Serianthes. The Guåhan (Guam) and Luta (Rota) endemic Serianthes nelsonii (known locally as Håyun lågu and Tronkon guåfi respectively) are closely related to South Pacific species. Serianthes kanehirae from Belau (Palau) and Wa'ab (Yap) are closely related to Malesian and Papuasian species. Phylogeographical patterns of Serianthes in Micronesia are discussed to inform conservation management. The ethnoecological study revealed interspecies relationships between people, animals, and plants remain strong. The traditional use of Ukall and Gumor (Serianthes kanehirae) on Belau and Wa'ab respectively remain part of Belau and Wa'ab's culture and are intertwined with rituals respecting the spiritual world. On Luta, Tronkon guåfi is an established flagship for endangered species conservation, while the last adult Håyun lågu tree on Guåhan became a rallying point for spiritual resistance when its habitat became threatened by military plans to construct a firing range. Despite its listing as critically endangered by the Endangered Species Act, its habitat is still at risk of being lost. The social movement guided by Prutehi Litekyan brought the community together to protect the Håyun lågu tree based on Indigenous belief systems. The social movement and policy research used a qualitative mixed-method approach to evaluate the dimensions of the Endangered Species Act in relation to environmental justice and biocultural rights. I concluded that a bottom-up co-management approach with polycentric networks best fits the social-cultural system of Guåhan. I propose Indigenous participation and the creation of an advisory council, comprising traditional and scientific knowledge holders, to advise on biocultural diversity preservation in the Mariana Islands.
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Naturally occurring etiologic factors affecting the health of breeding seabirds in the Bering SeaSeabird populations across the globe have experienced both significant instability and consistent overall declines in recent history. Seabirds in the Bering Sea of Alaska, USA appear to be severely affected by environmental changes, exhibiting large-scale shifts in behavior and distribution and increases in unusual mortality events (UMEs) in recent years. I analyze a selection of the naturally occurring pathogenic and toxicological factors affecting breeding seabirds in the Bering Sea region using an approach focusing on zoonoses and bioaccumulating toxins. Specimens were collected at three breeding colonies in the Bering Sea in 2018 and 2019, and were evaluated for the presence of several pathogens and toxins. First, I examined the frequency of Influenza A Virus (IAV) in several understudied clades of seabird host species (n=146 individuals) across the Bering Sea. Second, I used a novel set of genetic amplification and sequencing techniques for metagenomic analysis both to determine the respiratory microbiome and to detect the presence of potentially pathogenic microorganisms in northern fulmars (Fulmarus glacialis) on St. Matthew and Hall islands (n = 15). Finally, I sought to evaluate the levels of paralytic shellfish toxins (PSTs) in the digestive tracts of northern fulmars from St. Matthew and Hall islands (n = 14). Together, these studies detected several viral and bacterial pathogens, many with zoonotic potential. These included Coxiella, Plasmodium, Toxoplasma, and IAV. PSTs were also detected in birds sampled from 2019, indicating the presence of harmful algae in the Beringian food web. The detection of these etiologic factors along with the incidence of major morbidity and mortality events suggest these birds might serve as sentinel species, indicating variations in environmental change that can pose a significant risk to both ecological stability and human health in the region.
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Interpretations of climate change on grazing systems: the comparison of Arctic and Subarctic carexStresses imposed by climate change are altering arctic and subarctic ecosystem structure and function. On the Yukon-Kuskokwim River Delta (YKD) in subarctic western Alaska, Pacific Black Brant geese (Branta bernicla nigricans) are losing their available grazing lawns of shortstatured Carex subspathacea due to its conversion into a taller, less nutritious growth form. However, C. subspathacea on Alaska's Arctic Coastal Plain (ACP) grows in extensive lawns that remain short even when ungrazed. Our goal was to compare the growth responses between arctic C. subspathacea and subarctic C. subspathacea when grown in arctic and subarctic conditions. We used reciprocal common gardens to study the variation in height, tiller density, aboveground biomass, and green leaf nitrogen percentage between these reputed taxa. We explored the growth responses that occur in C. subspathacea when grown in the arctic and subarctic using linear mixed effect models. We found that environmental differences between these regions influence the morphology of these taxa. Subarctic C. subspathacea is phenotypically plastic, and was able to grow tall in subarctic conditions, while remaining short in the Arctic. However, arctic C. subspathacea was short in both gardens, suggesting arctic C. subspathacea will not grow tall under warming conditions. Understanding the functional causes of the difference between these two grazing systems is important for predicting the effects of future climate change on both regions. This study provides insight to how changing climate will impact these different growth forms and affect future grazing dynamics along arctic and subarctic coasts.
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Fasting status of Steller sea lion pupsFollowing population declines in species of concern, wildlife managers often seek to identify underlying causes to understand and predict population dynamics for better future management. Often, physiological and/or behavioral metrics are measurable markers of decline, and these are often detectable well before declines are measurable through population surveys. During the 1970's, 80's, and 90's Steller sea lion (SSL; Eumetopias jubatus) populations in the western portion of their breeding range declined by ~85%. Though declines in most regions have since stabilized or exhibited modest recovery, some subpopulations breeding in the Aleutian Islands continue to decline. In contrast, SSL subpopulations in eastern regions of their range have steadily grown since the 1970s. Prior studies on the maternal attendance behaviors of SSL have noted differences in the timing of parturition, the duration of the perinatal period, foraging trip duration of nursing females, and the duration of periods dams spend ashore tending their pups. Variability in these metrics has been associated with year, location, the dam's age and parity, environmental oscillations (i.e. El Niño Southern Oscillation), and pup age over the lactation period. This study utilized prior findings of predictable changes in metabolite concentrations while pups fasted during their mother's foraging trips as a new approach for assessing maternal attendance patterns. The distributions of fasting phase categories, assigned based on the relative concentrations of plasma betahydroxybutyrate and blood urea nitrogen, were compared across 12 subpopulations extending from eastern Russia along the coastal northern Pacific into southeastern Alaska from blood samples of 1528 SSL pups. Fasting phase categories were merged into Short and Long fasting durations to compare pups sparing critical proteins (relying on lipid reserves) to those with plasma profiles indicative of metabolic protein reliance (muscle & organ breakdown), respectively. Notably the subpopulations with the maximal (western Aleutian Islands) and minimal (eastern Aleutian Islands) observed proportions of Long fasting pups were in the same broad Aleutian Island region. Three metapopulations had significantly greater proportions of Long fasting pups: the western and central Aleutian Islands and the southern portion of southeastern Alaska. Due to contrasting population trends among these metapopulations, we suggest that both density-dependent and density-independent factors contributed to extended fasting durations in SSL pups.
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Balancing the conservation of wildlife habitat with road access for subsistence hunting in Yakutat, Alaska"This thesis was an interdisciplinary investigation with the goal of balancing the conservation of wildlife habitat with road access for subsistence hunting in Yakutat, Alaska. The problem posed by land managers and subsistence moose hunters revolved around the use of off-highway vehicles (OHVs; e.g. 'four-wheelers') for subsistence moose hunting and the potential disturbance OHVs have on moose. This complex social-ecological problem is becoming an increasingly common management dilemma faced by rural mixed cash-subsistence communities across the Circumpolar North. I addressed this problem in two chapters with a combination of methods from wildlife ecology, landscape modeling, subsistence land-use, and scenario planning. The data used for analysis in Chapter 1 was derived from a three-year moose GPS-collar dataset, remote sensing imagery, and mapped routes. I modeled moose distribution with multi-scale, seasonal and sex-specific resource selection functions in a GIS. The best-fit models suggested female moose were displaced by OHV routes. Male moose were displaced by routes or areas where routes were in close proximity to primary forage. A combined pattern of route avoidance was quantified beyond approximately 1 km of total vehicle travel/km²/day. Chapter 2 describes the application of distribution models from Chapter 1 to a social-ecological assessment of route closures. Meetings with land managers and moose hunters were conducted to identify their respective values and management goals. Then I evaluated the effect of four road closure scenarios on moose habitat and hunting access. A measure of hunting access was evaluated with interviews about hunter land-use patterns, as well as the mapping of harvest areas in a GIS. The results of the scenario evaluation showed the spatial arrangement of routes influenced the total amount of high probability moose habitat and access to preferred harvest areas. A balance in the conservation of wildlife habitat and the maintenance of hunting access may be found in the closure of routes through valuable moose habitat and the spatial arrangement of future routes around valuable moose habitat, within reach of important harvest areas. The results of the analysis and interdisciplinary approach may prove useful to land managers who must evaluate the trade-offs between wildlife habitat conservation and the increasing use of motorized access for contemporary subsistence hunting practices"--Leaf iii
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Ecological linkages between headwater streams and riparian and downstream habitats in the eastern Cascade Range, Washington, USA"I examined how headwater streams are ecologically linked with the terrestrial environment and upstream waters. I examined relationships between fish (rainbow and cutthroat trout), invertebrates, and habitat in 15 headwater streams in two ecoregions (wet, dry) and timber harvest scenarios (logged, unlogged) in the Wenatchee River sub-basin in the eastern Cascade Mountain Range, Washington state, USA. Fish biomass, density, and size were not related to ecoregion or to logging history. Invertebrate drift manipulations in 13 streams influenced fish movement (fish moved downstream in sites that were not supplemented with food) and diet (fish consumed less prey when drifting invertebrates were removed), but not fish growth or abundance. This study demonstrated that fish utilize drifting prey originating from upstream fishless waters, and that they are not able to compensate for the loss of this food. Headwater forest management may affect fish populations by altering prey resources where fish are food-limited"--Leaf iv
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In defense of quaking aspen (Populus tremuloides): the distribution and roles of phenolic glycosides and extrafloral nectaries within and among trees"I studied the concentrations of phenolic glycosides (PGs) from leaves with and without extrafloral nectaries (EFNs) in Populus tremuloides during an outbreak of the aspen leaf miner, Phyllocnistis populiella, in interior Alaska. P. populiella feeds on the contents of epidermal cells from both top (adaxial) and bottom (abaxial) surfaces of P. tremuloides leaves. The objective of this study was to assess the association of chemical and biotic defenses in P. tremuloides and their interaction with the insect herbivore P. populiella. The concentration of PGs (salicortin and tremulacin) was approximately 70% greater in leaves bearing EFNs than in those without EFNs from short trees (<2.5 m); leaves with and without EFNs did not differ significantly in PG concentration for tall trees (5-8 m). Leaf mining caused the induction of the foliar PGs following eight days of mining. There was no difference in the ability of leaves with and without EFNs to induce PGs in response to mining. The extent of mining damage was significantly and negatively related to the PG concentration, whereas EFNs were not related to the extent of mining. At the site level, I found no evidence for a tradeoff between these two putative forms of defense in P. tremuloides"--Leaf iii
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Lessons from the river: identifying factors that influence the comprehension of genetics research in a Yup'ik Eskimo community"The Center for Alaska Native Health Research (CANHR) follows a Community-Based Participatory Research (CBPR) approach to study genetic, nutritional, behavioral and cultural protective factors for obesity and Type 2 diabetes in Yup'ik Eskimo communities. As a multidisciplinary center, investigators have returned results of many of their research projects to participants and participating communities. However, traditionally, genetics research results are only returned to participants under specific conditions, which are not necessarily compatible with a CBPR approach. I ask how CANHR can improve its dissemination efforts, especially in the area of genetics research. I identify factors that influence how community members receive and understand health information, including genetics information. This study uses a grounded theory approach to qualitatively analyze interviews and focus group discussions with Yup'ik community members, identify themes and construct a theoretical narrative. The primary factors that emerged include communication pathways (ways in which information is transmitted in the community); health beliefs (what people already know and believe about health); and social location (a person's role in the community). I examine each of these through the framework of a river metaphor to provide recommendations for improving CANHR's dissemination efforts with the communities, including genetics research results"--Leaf iii
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Ecology and evolution of truffle fungi : the diversity of fungi associated with northern flying squirrels"This thesis explores the ecology of truffle fungi, a diverse assemblage of symbiotic mycorrhizal fungi that extend microscopic hyphae throughout forest floors, forming networks of foraging mycelium capable of transporting water, vitamins, minerals, and other nutrients to the roots of plants. Plant sugars are used for energy and as raw material for the creation of complex reproductive structures and vast water and nutrient gathering infrastructures essential to the survival of most plants. Truffle fungi are defined here by their ability to form mycorrhiza and produce truffles: hypogeous sporocarps that are excavated and consumed by animals ranging from squirrels to humans, resulting in the long-distance transport of spores. In Chapter 1, I compile and synthesize published information on the evolution and ecology of truffle fungi. In Chapter 2, I describe molecular techniques used to extract, amplify, and characterize fungal DNA from the scat of an endemic island population of northern flying squirrels, Glaucomys sabrinus griseifrons, which specialize in the consumption of truffles. Statistical analysis of RFLP data from clones of fungal DNA indicates much higher levels of fungal diversity in G. s. griseifrons scat than expected. I argue that the estimated numbers of fungi associated with G. s. griseifrons represent a baseline of diversity for fungi associated with mainland populations of Glaucomys sabrinus"--Leaf iii
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Terrestrial arthropod biodiversity on the Kenai National Wildlife Refuge, Alaska"Elucidating the causes of observed patterns of living diversity remains a central goal of ecology. To understand patterns of terrestrial arthropod diversity on Kenai National Wildlife Refuge (KENWR), arthropods were collected by sweep net on 255 100m2 plots systematically distributed at 4.8km intervals across KENWR. I calculated three indices of diversity for 90 families conveying information on richness and evenness for each site. Using Bayesian Model Averaging, I found all indices were strongly influenced by site productivity, local climate, time of sampling arid plant species richness. Physiographic variables were less important than climate for determining arthropod distributions. Because many species are expected to alter their distributions in response to accelerated climate change, I assessed the use of occupancy models for monitoring those shifts on KENWR. I compared rotating panel and periodic census sampling designs using Monte-Carlo simulations given a range of occupancy and detectability values. Both designs estimated detectability within single visits and provided reasonable precision and accuracy on occupancy estimates of species with detection probabilities> 0.5, but the rotating panel design was preferred because it yielded information at shorter time intervals. I recommended adding sites sampled in consecutive seasons to better estimate local extinction and colonization rates"--Leaf iii
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Cellulose degrading microorganisms in Alaskan boreal forest soil"Cellulose is the most abundant organic compound on earth, and has been studied intensely. This thesis includes a review of previous studies and literature compiled on cellulose degradation and its significance to biofuel production. It also reports a study designed to advance knowledge of cellulose degrading bacteria and fungi in Alaskan boreal forest soil. This was accomplished using stable isotope probing (SIP) in soil microcosms and community analyses of organisms colonizing in situ buried Birch Tongue Depressors (BTDs). We identified which organisms incorporated a 13C cellulose label into their genomic material, finding degradation to be dominated by fungi. Fungi from the genera Sebacina, Geopyxis and Geomyces were the most prevalent in fungal ITS clone libraries. The most abundant bacterial cellulose utilizers were members of the order Sphingobacteriales, along with several unclassified Bacteria; the well-known cellulose degrader Cellvibrio was present, but found less frequently. The microbial community colonizing BTDs shared some taxa in common with bacterial SIP results, but differed from fungi identified with SIP. Using SIP, we identified a variety of soil microorganisms active in utilization of carbon from cellulose. These findings are significant for understanding fundamental ecosystem carbon cycling and may have application to cellulosic biofuel production technologies"--Leaf iii
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Small game and furbearers of the Rampart Dam impoundment areaProbable effects of the proposed Rampart Dam on small game and furbearers of the impoundment area are presented* Checklists were made of 71 birds and 31 mammals* An aerial census of beaver gave an estimate of 80,000 beaver in the study area. Furbearers (excluding red squirrel, ground squirrel, and coyote) have produced a rounded average annual income of $143,000. Potential value of furbearers (except coyote and ground squirrel) was estimated to be $4 million per year. Approximately 1,200 of the study area residents depend on small game and furbearers for about 44% of their annual income. From 1958 to 1962 the average annual value of the fur harvest was $45,000, and the average annual small game harvest was valued at $35,500. Annual per capita income from all known sources during this period averaged $124. It was concluded that Rampart Dam would be detrimental to small game and furbearers upon which most of the human population of the area is dependent.
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Use of anthropogenic foods by glaucous gulls (Larus hyperboreus) in northern Alaska"Glaucous Gulls are abundant predators in northern Alaska and prey upon several bird species of conservation concern. To assess the benefit gulls may receive from scavenging garbage, I studied diet and reproduction at eight to ten breeding colonies in northern Alaska in 2008-2009. Garbage occurrence in diet was positively correlated with fledging rate; thus any development that increased available garbage could potentially subsidize gull populations through enhanced reproductive success. Garbage could also increase gull populations by enhancing subadult survival. Subadult gulls around the city of Barrow consumed much more garbage than breeding adults, which apparently switch to a mostly natural diet. If garbage enhances subadult survival, more gulls may survive to adulthood, which could impact prey species. When Barrow switched to incinerating garbage instead of disposing it in a landfill, garbage in subadult gull diet decreased. Using stable isotope analysis of gull chick feathers, I found that the diet samples (pellets and food remains) I used in these analyses overestimated gull use of birds and underestimated use of fishes, but usually accurately portrayed relative importance of garbage. Biases in these samples should be considered when assessing the potential impact of gulls on their prey"--Leaf iii
