Now showing items 2072-2091 of 3321

• #### Pandalid shrimps in a tidewater-glacier fjord, Aialik Bay Alaska

Vertical migration and food habits of pandalid shrimps in Aialik Bay, a tidewater-glacier fjord, were related to suspended sediment load and available food resources. Suspended sediments from subglacial streams resulted in Secchi depths of 0.4-1.0 m near the glacier, increasing with distance from the glacier to 1.0-5.0 m near the sill. A large proportion of the Pandalus borealis and P. goniurus populations responded to reduced light in the upper bay by remaining in midwater throughout the day and night. Shrimp food resources, represented by zooplankton and benthos, were reduced in abundance and diversity near the glacier as compared to the region near the sill. Shrimps fed more intensively near or at the bottom than in midwater. The most common items in stomachs of P. borealis were unidentifiable organic matter (84.5%), sediment (83.1%), crustacean fragments (60.9%), identified crustaceans (16.9%), mollusks (16.3%), foraminiferans (15.1%), and plant material (10.0%).
• #### Pandering to glory: Sheldon Jackson's path to Alaska

Presbyterian missionary Sheldon Jackson is a celebrated figure in Alaska history. He is known predominantly for his efforts facilitating the establishment of public schools for Alaska Native people during the late nineteenth century. Jackson's methods have been historically overlooked as being reform-minded initiatives characteristic of Indian assimilation. As a result, historians have concluded that Jackson was a humanitarian with benevolent intentions. Unfortunately, such assessments ignore Jackson's educational platform, which was built upon fictitious slander against indigenous people and the manipulation of Christian women. In addition to speaking tours, Jackson published many editorials, articles, and books alleging that Alaska Native people were barbarous monsters. The propaganda Jackson employed in Alaska was no different from the propaganda he used against Mormons and Native Americans. However, Jackson was maligned for his strategy in the continental United States, whereas in Alaska he was celebrated as a reformer and an authority figure due to ignorance about the northern territory. Alaska captured the public imagination, and Jackson lied about Alaska Native culture for the remainder of his career in order to maintain his Christian enterprise.
• #### Paralytic shellfish poisoning: the relationship between Alexandrium abundance and psp toxins on Kodiak Island, Alaska

Paralytic shellfish poisoning (PSP) events have severe negative impacts on Alaska commercial shellfish fisheries as well as recreational and subsistence harvests. This study, designed to improve existing PSP monitoring programs, involved the use of a rapid sandwich hybridization assay to detect and quantify the relative abundance of Alexandrium catenella based on species-specific LSU rRNA targeted oligonucleotide probes. Blue mussel (Mytilus edulis) toxicity, expressed as saxitoxin equivalents, was determined using the ³H-Saxitoxin receptor binding assay. Shellfish toxicity was relatively low in both 2000 and 2001 compared to historically high values on Kodiak, but exhibited pronounced late spring and late summer peaks, in both years at four to seven sampling sites. Temporal and spatial variability in shellfish toxicity among sites, seasons, and years suggested dynamic, and possibly unpredictable, Alexandrium bloom events. Importantly, DNA probe data revealed a strong association between Alexandrium abundance and shellfish toxicity. The results also demonstrated that increases in Alexandrium abundance preceded elevated toxin levels in shellfish, indicating that this assay may prove useful as a monitoring tool to predict toxic events in shellfish before they are harvested. Water column nutrients and climate data were evaluated to determine if bloom-triggering mechanisms could be identified.
• #### Parasites and skeletal indicators of anemia in the eastern United States

The goal of this research is to examine the influence of parasitic infection and diet in the etiology of anemia in prehistoric human populations of the eastern United States. Prehistorically, anemia is often attributed to a nutrient-deficient diet, while parasite infection is discussed as a secondary cause if at all. However, parasite infection is a leading cause of anemia in the developing world today. Modern epidemiological studies have demonstrated that parasites thrive or perish under particular environmental conditions, and risk for parasite infection can be predicted based on environment using GIS. Here I apply this method to see whether environmental conditions, acting as a proxy for parasite infection risk, can predict prehistoric skeletal lesion rates for porotic hyperostosis and cribra orbitalia, lesions thought to reflect acquired anemia. Rates of porotic hyperostosis and cribra orbitalia in the skeletal remains of children and adults were collected from published data for 22 sites in the eastern United States. GIS was used to gather comparable environmental data. Soil drainage, elevation, precipitation, temperature and the surface area of bodies of water were recorded within a 15 km radius of each site. Carbon isotope data deriving from bone collagen and historic hookworm infection rates were also collected when available. Multiple linear regression was used to test how well environmental variables could predict lesion rates. Statistically significant correlations were found for both adults and children, but the strength and direction of relationships with environmental variables were inconsistent. It is possible that the correlations were related to parasite infection, but it is also possible that the skeletal 'lesions' may result from post-mortem bone degeneration rather than anemia. The correlations for porotic hyperostosis and cribra orbitalia were stronger when examined separately than when examined together, suggesting that the two conditions may have separate etiologies; however, the sample sizes were too small to provide the statistical power required for drawing strong conclusions. Comparison of children and adults showed stronger correlation for children, though when observing the lesions separately this pattern was not consistent. Collagen carbon values and historic hookworm infection rates correlated with lesion rates in children but not adults, perhaps because of differential healing in adults. These results demonstrate that environmental conditions and skeletal lesions are correlated, but the underlying mechanism for this remains unclear. Larger sample sizes would allow for more robust statistical analyses of the trends observed here. Nevertheless, these results do confirm that porotic hyperostosis and cribra orbitalia cannot be assumed to be the result of nutrient-deficient diets. Interpretation of skeletal data for assessing health in the past must also consider the natural and social context in which individuals lived.
• #### Parental perceptions of play: the influences of parent gender, gender role attitudes, and parenting styles on parent attitudes toward child play

The literature overwhelmingly demonstrates that play supports healthy social, emotional, physical, and cognitive development. Efforts to understand parents' support of child play seek to identify parent attitudes toward play, ways in which parents facilitate play for their children, and how they participate in play. Previous findings indicate parent valuation of play is an important factor for childhood play time and finds differences between mothers and fathers in parent-child play. While much research has been done to understand how mothers and fathers play with their sons and daughters, few studies have investigated what factors influence parent valuation of play or facilitate certain types of play. This study used a moderated mediation model to explore how parental attitudes about gender roles influence perceptions of play through parenting style and how this effect may be different for fathers and mothers. Analyses were also performed to understand the relationships between parent attitudes and parent play behaviors. The findings suggested egalitarian gender role attitudes predicted a higher valuation of play and more permissive mindsets toward cross-gender play for both mothers and fathers. Conversely, traditional gender role attitudes were predictive of less permissive mindsets toward cross-gender play for both mothers and fathers. A moderated mediation was found for fathers with traditional gender role attitudes and a permissive or authoritarian parenting style. Fathers with traditional gender role attitudes and a permissive parenting style were less likely to value play for child development. Fathers with traditional attitudes and an authoritarian parenting style had less permissive mindsets toward cross-gender play. Additionally for both mothers and fathers, authoritative parenting was correlated with increased parent play behaviors, while authoritarian parenting was correlated with decreased parent play behaviors. These findings support previous literature in that parent gender and gender role attitudes do appear to influence parent attitudes toward play. They also contribute to our understanding of parent gender differences and the way that parenting style influence this relationship. In addition, parenting style was found to be a facilitator of parent-child play. These findings contribute to an understanding of what kind of parents value play and can be used to inform family psychotherapy and parent education about play.
• #### Particle dynamics in the plasma sheet

Trajectories of charged particles in the tail region of the earth's magnetosphere are studied using a model magnetic field. The particles form a thin sheet-like structure in the magnetotail called the plasma sheet. It is shown that most trajectories are categorized by two dimensionless parameters. One of them is equal to the ratio of the cross-tail electric force to the magnetic force in the midplane and determines the maximum particle energization. The other parameter is the ratio of the plasma sheet thickness to the particle gyroradius in the midplane and determines the degree to which the particle motion is adiabatic. All previous attempts at studying trajectories in the magnetotail are shown to be applicable only over limited ranges of the two parameters. Hence those studies are combined into a common framework, and those trajectories which have not been studied previously are added for completeness.
• #### Particle simulations of magnetic field reconnection and applications to flux transfer events

Basic plasma processes associated with driven collisionless magnetic reconnection at the Earth's dayside magnetopause are studied on the basis of particle simulations. A two-and-one-half-dimensional (2$1\over2$-D) electromagnetic particle simulation model with a driven inflow boundary and an open outflow boundary is developed for the present study. The driven inflow boundary is featured with a driving electric field for the vector potential, while the open outflow boundary is characterized by a vacuum force free condition for the electrostatic potential. The major findings are as follows. (1) The simulations exhibit both quasi-steady single X-line reconnection (SXR) and intermittent multiple X line reconnection (MXR). The MXR process is characterized by repeated formation and convection of magnetic islands (flux tubes or plasmoids). (2) Particle acceleration in the MXR process occurs mainly in O line regions as particles are trapped within magnetic islands, not in X line regions. The MXR process results in a power law particle energy spectrum of $f(E)\sim E\sp{-4}$. (3) Field-aligned particle heat fluxes and intense plasma waves associated with the collisionless magnetic reconnection process are also observed. (4) When applied to the dayside magnetopause, simulation results show that the MXR process tends to generate a simultaneous magnetic field perturbation on both sides of the dayside magnetopause, resembling the observed features of two-regime flux transfer events (FTEs). (5) An intrusion of magnetosheath plasma bulge into the magnetosphere due to the formation of magnetic islands may lead to the layered structures observed in magnetospheric FTEs. (6) In the current sheet, the enhanced tearing mode instability caused by the driving force applied at the driven inflow boundary creates an energy source at a specific wavenumber range with $k\sb{z}L\sim$ 0.3 in the modal spectrum of the magnetic field $B\sb{x}$ component. An inverse cascade of the modal spectrum of $B\sb{x}$ leads to the formation of the large-scale ordered magnetic island structures observed in the simulations. (7) In addition, the results of a theoretical study show that the tearing mode instability, and hence the magnetic reconnection at the dayside magnetopause, do not exhibit strong dependence on the magnetosheath $\beta$ values.
• #### Particles in the Pacific: how productivity and zooplankton relate to particles in the deep sea

The magnitude and spatio-temporal patterns of particulate material flux from the surface ocean through mesopelagic and bathypelagic depths determines sequestration of atmospheric carbon and the food supplied to deep-dwelling ocean life. The factors that influence how and where this organic material is exported from euphotic depths are poorly understood. Zooplankton are thought to play a key role in modulating the transport of surface-produced particles to depths through consumption, fragmentation, active diel vertical migration, and fecal pellet production, thus it is important to study both particulate matter and zooplankton in tandem. In this study, I use an in-situ optical instrument, the Underwater Video Profiler 5 (UVP5), to describe broad scale patterns of large (> 100 μm) particles and zooplankton across a longitudinal transect of the Pacific Ocean during April to June 2015. Satellite-derived surface chlorophyll-a was employed to describe the timescales over which particles arrive in meso- and bathypelagic depths after a productivity peak. High abundances and volumes of particles are noticeable beyond the euphotic zone across the Equator, transition zone, and the sub-arctic Pacific, indicating increased export in these high-nutrient low-chlorophyll (HNLC) areas. In two of these areas, the Equator and transition zone, large abundances and volumes of particles extend into bathypelagic depths. High abundances of zooplankton were seen in all areas where high abundances of particles are seen in bathypelagic waters. Rhizaria were revealed to be pervasive across all biogeographic regions, and appear to play a role in particle attenuation in the sub-arctic Pacific. The insight into patterns between particles, zooplankton, and productivity identify HNLC regions as deserving more detailed examination in future studies of biological pump efficiency.
• #### Passively encouraging offline networking in small, concentrated communities through UI/UX design

The goal of this project is to identify whether it is possible to encourage users to communicate with one an other face-to-face through User Interface (UI) and User Experience (UX) design. It is well known that users can be maliciously manipulated by design elements and that concerns have been raised about the effects o f social media on interpersonal communication. The key is to find non-harmful means of guiding users to the desired action of speaking face-to-face with others. User testing for a custom web app was conducted for the purposes of this project. It is hoped that the results will provide developers with new consideration for UI and UX design.

• #### Pathophysiology of infections by the gastric trichostrongylid Obeliscoides in a rabbit model system

The gastric trichostrongylid parasite Obeliscoides sp. was isolated from Alaskan snowshoe hares (Lepus americanus) and passaged 3 times in laboratory rabbits (Oryctolagus cuniculus). Despite its low fertility, the isolate persisted, often as occult infections, for up to 45 weeks and produced physiologic effects in clinically normal rabbits. Prominent eosinophilic and hyperplastic lesions of the gastric mucosa occurred during post-inoculation weeks (PIW) 2-15, while mononuclear aggregations were seen in older infections. Gastric lesion severity was directly related to size of the Obeliscoides population, which declined over time and was smaller in secondary infections. Anorexia occurred within 3 weeks of infective larval inoculation in 12 (of 21) primary and 2 (of 10) secondary infections. Serum total protein, albumin, and the A/G ratio were significantly reduced in anorectic infected rabbits compared to fasted uninfected rabbits. Fecal N excretion was significantly increased between PIW 1 and 5 in rabbits with primary infections, and during PIW 1 and 2 for those with secondary infections. Nitrogen absorption was enhanced during PIW 5-15 of primary infection. Serum gastrin concentrations, determined for the first time in Obeliscoides-infected rabbits by radioimmunoassay, were significantly elevated in primary infections during PIW 6 and 7, while hypokalemia was apparent during PIW 5. Hypermagnesemia occurred in both primary and secondary infections between PIW 8 and 15. Other serum constituents and concentrations of N, Ca and P in the gastrointestinal tract and feces remained largely unchanged. Total mean retention time (TMRT), 31.8 h, and GI turnover time (GITT), 26.3 h, of the fiber component (determined with Ce-141-marked fiber $>$355 microns) were significantly prolonged in secondary infections during PIW 16 to 26. TMRT (53.0 h) and GITT (57.0 h) of the liquid component (using Cr-51 EDTA), were determined for the first time in rabbits, and were not significantly changed by Obeliscoides infection. Persisting populations of this Obeliscoides isolate caused physiologic and pathologic alterations in clinically healthy rabbits. Because these effects were similar to those seen in ruminant Ostertagia spp. infections, this laboratory model could be useful in understanding the pathophysiology of costly production losses that occur in parasitized commercial livestock.
• #### Pathway to Alaskan statehood: the historical narratives of Jack Coghill, Vic Fischer, Katie Hurley, and D.A. Bartlett, and their presence at the Alaska Constitutional Convention

The aim of this thesis is to compare the commonalities and differences in the oral narratives of four participants of the Alaska Constitutional Convention, John B. “Jack” Coghill, Victor “Vic” Fischer, Katherine “Katie” Hurley, and Doris Ann “D.A.” Bartlett. Applying thematic analysis to the interviews, themes, or codes were extracted from the interviews and unified into code families: “family,” “work,” “Alaska Constitutional Convention,” and “Alaska Constitution,” with other code families supporting these four. The “Alaska Constitutional Convention” becomes the super code, or main theme of this thesis. The research explores three themes: non-partisan politics at the Alaska Constitutional Convention, the camaraderie among the delegates and staff at the Alaska Constitutional Convention, and gender differences among Coghill, Fischer, Hurley, and Bartlett.
• #### Pattern and process in volcano seismology

The patterns of occurrence and the underlying processes of two important seismological phenomena at volcanoes, earthquake swarms and volcanic tremor, were investigated. A global database of volcanic earthquake swarm parameters was compiled and was used to evaluate the March 10-14, 1996 seismo-volcanic crisis at Akutan Volcano, Alaska. Earthquake swarm durations and magnitudes were compared with eruptive activity using this database. Trends identified using the database suggest that the Akutan swarm was not precursory and, no eruption occurred. We postulate that a deep instrusion with a large opening component occurred under the flanks of Akutan. The global swarm database has provided an important baseline and has proved to be useful in preparing eruption scenarios for public information releases. The duration-amplitude distribution or frequency-size scaling of volcanic tremor was also examined. The hypothesis tested was that the duration-amplitude distribution may be approximated by an exponential function. The exponential model, implying a scale-bound source process, is found to be a better fit to data then a power-law (scale invariant) model. The exponential model gives a satisfactory description of tremor associated with a wide range of volcanic activity. We propose that exponential scaling of tremor amplitude is due to fixed source geometry driven by a variable excess pressures. This implies that the characteristic amplitude of the duration-amplitude distribution is proportional to a geometric dimension of the source. Broadband seismic data recorded at Arenal volcano, Costa Rica, provide new constrains on tremor source processes. Arenal's tremor contains as many as seven harmonics, whose frequencies vary temporally. This source is inferred to be a shallow, 200-660 m-long resonator, radiating seismic energy from displacement antinodes. We infer that the resonator is gas-charged magma with variable bubble concentration within the conduit and also changes as a function of time, thereby changing the acoustic velocity and the boundary conditions. Polarization analyses for the fundamental mode show particle motion azimuths abruptly rotating, which may be explained by a decrease in incidence angle near the recording site. We suggest that energy for this mode is radiated predominantly from a displacement antinode that is changing position with time.
• #### Patterns and environmental drivers of juvenile sablefish movement in Southeast Alaska

Sablefish Anoplopoma fimbria are a long-lived, deep-dwelling groundfish that inhabit the North Pacific Ocean, ranging from northern Mexico to the Gulf of Alaska to Japan, supporting one of Alaska's most valuable commercial fisheries. After decades of heavy fishing, declines in the Sablefish population led to significant fishing restrictions but few strong year classes developed in recent years. Most Sablefish research has focused on the larval, near-surface juvenile, or adult life history stages, but few studies have examined post-settlement juvenile Sablefish in nearshore areas. This study used acoustic telemetry to understand the presence and movement of juvenile Sablefish in a nursery area in Southeast Alaska. Throughout the summer and fall of 2015 and 2016, 40 juvenile Sablefish implanted with acoustic transmitters were monitored using an array of eight fixed receivers in St. John Baptist Bay, Baranof Island, Alaska. We quantified the movement patterns of 28 juvenile Sablefish using displacement from the head of the bay, daily distance traveled, daily duration within the bay, unique movement types among individuals, and movement in relation to environmental variables. From these analyses, we show that juvenile Sablefish exhibit fidelity to the middle-head region of the bay, display relatively high rates of daily movement and residence, demonstrate three distinct movement patterns, and are influenced by environmental variables like water temperature, diel state, moon phase, and day of year. Our results show that juvenile Sablefish exhibit seasonality in movements as they progressively emigrate from the bay throughout the summer and fall. Certain factors were found to increase the likelihood of movement for juvenile Sablefish, perhaps allowing them to remain in suitable environmental conditions. This study fills a gap in our knowledge of Sablefish early life history and reinforces the importance of nursery areas like St. John Baptist Bay for juvenile Sablefish prior to recruitment into commercial fisheries.
• #### Patterns and potential solutions to coastal geohazards at Golovin, Alaska

The objective of this research is to measure the localized potential for shoreline change and flooding on the Golovin spit, Alaska. Long-term trends of shoreline change have been measured using multi-temporal aerial photography and satellite imagery from 1972-2013, while seasonal and annual changes in shoreline geometry have been measured by re-surveying the beach in July 2012, July 2013, and October 2013. The local bathymetry was updated with data derived from the WorldView-2 satellite to increase the spatial resolution of nearshore topography. These inputs were then integrated to establish an XBeach 1-dimensional numerical model connecting offshore storm water elevations to nearshore dynamics. The spit was found to experience episodic erosion of beach sediments, followed by sediment accretion. This resulted in a dynamic position of the shoreline, with no long-term trend in either the offshore or landward directions. Modeled storms resulted in inundation of low elevations of the spit at a 5- year return interval, with inundation of infrastructure on a 25-year return interval. The modeled results suggest overwash of the entire spit at the 50-100-year return interval. All models were based on the best available forcing data from hindcast modeling. Reinforcing and increasing the elevation of a temporary berm and/or a permanent levee structure, using a 25-year return interval as a design parameter, would help to reduce localized flooding on the spit, and may be considered in the future.
• #### Patterns in size, growth, and condition of juvenile chum and pink salmon in the northeastern Bering Sea

The Bering Sea has alternated between warm and cool spring thermal regimes, as defined by May sea surface temperature, and in recent years has remained in a "cool" state. Differences in spring thermal regime influence the timing of sea ice extent in the southeastern Bering Sea (SEBS) region, with warm springs facilitating early ice retreats and cool springs resulting in later ice retreat. A recent conceptual model for relating production to higher trophic levels in the SEBS proposes that during years of early sea ice retreat, phytoplankton blooms occur in warm water and support small, lipid-poor species of zooplankton. Conversely, years of late sea ice retreat results in an ice associated bloom that supports large, lipid-rich species of zooplankton. As a consequence the energy density of prey sources available to higher trophic levels is reduced during warm years and enhanced during cool years. While the northeastern Bering Sea (NEBS) has consistently supported an ice-associated bloom, it is likely that productivity in the SEBS influences trophic-level connections in the NEBS. In order to examine this possibility, we extended this conceptual model to juvenile salmon and compared size and condition of juvenile chum (Oncorhynchus keta) and pink (O. gorbuscha) salmon in the NEBS between spring thermal regimes of the SEBS. We hypothesized that juvenile salmon would be longer in warm years and more energy dense in cool years. In years with cool springs, pink salmon were shorter and chum salmon exhibited greater energy density, but no other aspects of size and condition differed significantly between spring thermal regimes. We further examined relationships of size, growth, and condition of juvenile salmon with environmental variables within the NEBS. For both species, length increased over the time of the surveys; longer individuals were caught at stations with greater bottom depths and in cooler sea-surface temperatures, while individuals with high length-corrected energy density were associated with cooler temperatures and shallower depths. We used insulin-like growth factor-1 (IGF-1) concentrations as an indicator of relative growth rate for fishes sampled 2009-2012 and found fish exhibited higher IGF-1 l concentrations between 2010-2012 than in 2009. IGF-1 concentrations were positively correlated with temperature for juvenile chum salmon and with depth and length for juvenile pink salmon. The consistent appearance of depth (indicating distance from shore) in the best size and condition models was interpreted to indicate that as juvenile salmon moved offshore, they were allocating more energy to growth than fat storage over the course of the surveys. The association of cooler temperatures with greater energy density and longer lengths may reflect direct effects of temperature on salmon physiology as well as indirect effects on food quantity or quality indirect. Overall, recent conditions of the NEBS appear to successfully contribute to the growth and condition of the juvenile chum and pink salmon. Finally, we compared indicators of energy allocation between even and odd brood-year stocks of pink salmon and found the even broodyear stocks were more energy dense while odd brood-year stocks exhibited higher growth rates. These results reflect differences in energy allocation between brood-year stocks of juvenile pink salmon and suggest that the two brood-year stocks may respond differently to changing climate.
• #### Patterns of and controls over nitrogen inputs by green alder (Alnus viridis ssp. fruticosa) to a secondary successional chronosequence in interior Alaska

Patterns of and controls over N₂ fixation by green alder (A. viridis) were studied in post-fire, mid-succession, and white spruce upland forests in interior Alaska during 1997-2000, focusing on the hypothesis that ecosystem-level nitrogen (N) inputs decrease with successional development. Across all stands, alder created islands of elevated soil N and carbon, depleted soil phosphorus (P), and more acidic soils, effects which translated to the stand-level in response to greater alder stem density. Rates of N₂ fixation (measured by acetylene reduction = ARA) closely tracked plant phenology during the 1997 (a drought year) and 1998 (a year of normal precipitation) growing seasons. During 1998, stands with higher maximum ARA had higher %N in the O, A, and C soil horizons. N₂-fixation rates were influenced by soil P, as evidenced by the findings that maximum ARA was positively correlated with foliar N:P ratios, and with subcanopy %P in the O and A soil horizons. During the drought year, alder leaf %P and leaf N resorption were lower and leaves were thinner when compared to 1998. Drought effects were most pronounced in mid-succession where alder exhibited reduced ARA ( -76%), leaf %P ( -14%), leaf thickness ( -40%), and lower leaf resorption of P ( -66%) and N ( -78%). Although ARA and nodule biomass did not differ among stand types, increases in alder densities with successional time translated to increasing ecosystem-level N inputs across the chronosequence. These results contradict established theory predicting a decline in N₂-fixation rates and N₂-fixer abundance during successional stand development.
• #### Patterns of behavioral entrainment in mice

The experiments described in this Dissertation were designed to assess the process by which the master circadian clock in the suprachiasmatic nuclei (SCN) can be entrained by normocaloric scheduled feeding. Mouse lines that differ in some circadian rhythm characteristics and features of the SCN were used in these experiments. The initial experiment showed that the lines differ in the percentage of individuals that entrained to scheduled feeding. In mice that entrained to scheduled feeding, both wheel-running activity and the molecular clock in the SCN were synchronized to the time of food provision. The molecular clock in the SCN remained in phase with the free-running light entrainable activity component in mice that did not entrain to scheduled feeding. Subsequent experiments were performed to determine if line-specific differences in entrainment were related to differences in circadian rhythm characteristics. Several circadian characteristics showed line effects, but no differences between mice that entrained and those that did not entrain were found. The next series of experiments assessed the influence of non-photic factors not directly related to food availability and food ingestion. The results indicated that the timing of food availability relative to the phase of the SCN during the initial phase of the experiment, and factors related to disturbance, influenced entrainment. Three factors suggest involvement of the FEO in entrainment to scheduled feeding: 1) it is a circadian oscillator that is entrained by scheduled feeding; 2) entrained mice express robust food anticipatory behavior; and 3) the time of food provision corresponds to the peak of mPER2 expression in the SCN of entrained mice. The results of the disturbance experiments raise the possibility that the entrainment signal may be generated by a system other than the FEO, perhaps one related to arousal state or reward processes. Ultimately, multiple factors influencing entrainment of the SCN and SCN-controlled circadian rhythms by scheduled feeding are likely to be identified. These factors may include the combined influence of all non-photic signals received by the SCN, differences entrainment signal strength, and differences in the sensitivity or responsiveness of the clock mechanism due to genetic variation.
• #### Patterns of genetic variation among various Beringian birds

Every animal has two different sets of genes, the mitochondrial genome and the nuclear genome. They are inherited independently of each other and can have dissimilar evolutionary histories. For this thesis, I examined the correlation of the mitochondrial (using direct sequencing of mitochondrial DNA) and nuclear (using a fragment-based technique, AFLPs) evolutionary histories in Beringian birds. The first study looked at relationships among a within-Beringia radiation of birds, the Aethia auklets. I was able to infer a resolved phylogeny using mitochondrial DNA, but found a polytomy using nuclear DNA. The lack of correlation between the genomes is either the result of incomplete lineage sorting or reflects the fact that AFLPs may not be an appropriate technique to survey nuclear diversity at this level of divergence. In the second study, I examined the correlation between taxonomic status, mitochondrial divergence, and nuclear divergence among nine lineages of trans-Beringian birds. I found no relationship between any of the three variables, suggesting that trans-Beringian birds have complex and discordant genetic and phenotypic histories.