• Distribution and biogeography of the Alaskan hare (Lepus othus)

      Cason, Michelle M.; Olson, Link; Booms, Travis; Hundertmark, Kris; Sikes, Derek (2016-05)
      The Alaskan Hare (Lepus othus Merriam 1900) is the largest lagomorph in North America but remains one of the most poorly studied terrestrial mammals on the continent. Its current distribution is restricted to western Alaska south of the Brooks Range, but historical anecdotal accounts of occurrences north of the Brooks Range (the North Slope) have led to confusion over its past, present, and predicted distribution. To clarify the historical range of L. othus, we surveyed North American museum collections and georeferenced voucher specimens (Supplemental File Appendix 1.1). We also located a specimen from the North Slope of Alaska long presumed lost and whose identity had come to be questioned. The rediscovery of this missing specimen suggests the occurrence of at least one Alaskan Hare on the North Slope as recently as the late 1800s. Because unforested ecosystems such as tundra and Arctic grasslands have decreased in Alaska since the last glacial maximum, and L. othus occurs in unforested habitat, we expected to observe low genetic diversity in the mitochondrial control region of L. othus. However, with recently collected specimens from regions in Alaska that were poorly represented in the past (i.e. Alaska Peninsula, Little Diomede, and Kotzebue Sound), we discovered more genetic diversity and population structure than was found in previous studies, including similar haplotypes from the Alaska Peninsula and from eastern Russia. This suggests there may have been 2 distinct colonization events of northern hares in Alaska, or introgression from L. timidus and a mitochondrial sweep that has been restricted to the Alaska Peninsula and Bristol Bay area. Our morphological analyses of the difference between the two subspecies, L. o. othus and L. o. poadromus, were ambiguous, with principal components analysis and simple linear regression indicating the presence of a latitudinal size cline and discriminant function analysis revealing successful group assignment that is not solely based on latitude. Our research clarifies the current and recent distribution of the Alaskan Hare and reveals more genetic diversity than previously suspected in the mitochondrial control region. We also observed a new biogeographic pattern and closer mtDNA association with L. timidus, which, combined with new island specimens and observations, suggests gene flow across the Bering Strait. It also highlights the importance of maximizing sample sizes and sampling widely across a taxon’s geographic distribution.
    • Distribution and ecology of exotic plants in Wrangell-St. Elias National Park and Preserve, Alaska

      McKee, Paul Christian (2004-12)
      The distribution of exotic plants and site factors influencing their abundance on roads and trails were studied in Wrangell-St. Elias National Park and Preserve during the summer of 2003. Seventeen species of exotic plants were found in the park at 173 locations. The most common species (Taraxacum officinale, Plantago major) were present at all study sites, while some (Trifolium spp., Bromus inermis, Leucanthemum vulgare) were restricted to specific disturbance types and particular areas. Though sampling was limited to areas in which exotic plants were growing, percent cover of exotics was not a significant component of sample sites, and exotic species richness was low at all sampling locations at 1.42 species per m². Data were analyzed using ordination and multiple regression to determine variables most responsible in explaining variation in exotic plant communities. Statistically significant site variables correlated with percent cover of exotics included percent cover of vascular native plants, percent cover litter, and percent bare soil at most study sites. The importance of these variables indicates that the presence of exotic plants in Wrangell-St. Elias is closely linked to disturbance, and that the invasion of exotic plants is in the initial phases.
    • Distribution and movement of juvenile tanner crabs Chionoecetes bairdi in Glacier Bay National Park

      Nielsen, Julie Kristine (2005-12)
      Spatial segregation of adult and juvenile Tanner crabs was observed in conjunction with glacial landscape features during a comprehensive systematic survey of Glacier Bay National Park, Alaska, in 2002. Hot spots (clusters of high values) of catch per unit effort for juveniles occurred mainly in two narrow glacial inlets, whereas most adult hot spots occurred in the central portion of the bay. Overall, juveniles were associated with shallower depths and warmer temperatures than adults. However, in juvenile hot spot areas, where adults were rare, juveniles were associated with greater depths and colder temperatures than adults. Glaciated landscapes may provide spatial refuges from predation and nursery areas for juveniles. Tagging methods with high trans-molt retention need to be developed for direct measurement of ontogenetic movement. A laboratory study was conducted to determine trans-molt survival and retention of Floy T-bar tags in juvenile Tanner crabs. Approximately half of crabs in all tagging treatments survived and retained tags through a molt. Trans-molt retention of Floy tags is hindered by complex morphology of the Tanner crab carapace.
    • The distribution and phylogeography of the Alaska marmot (Marmota broweri)

      Gunderson, Aren M. (2007-12)
      The taxonomic and distributional status of the Marmota broweri has been the subject of much debate and confusion since it was first described as a subspecies of the hoary marmot (M caligata). Through a review of all museum specimens, published accounts of this species, field surveys, and the identification of previously unidentified marmot specimens we have determined the current distribution of the Alaska marmot to include the Brooks Range, the Ray Mountains, and the Kokrines Hills of northern Alaska. The Yukon River forms the boundary between the peripatric distributions of M broweri and M caligata in Alaska. Since M broweri was a resident of Beringia during the Pleistocene, I expect the phylogeographic structure of Alaska marmots (M broweri) to exhibit the signature of persistence in Beringia and subsequent expansion into glaciated areas. My objective is to investigate the phylogeographic structure of Alaska marmot populations through phylogenetic tree construction, measures of genetic diversity, a mismatch distribution, and nested clade analysis of DNA sequence data from the mitochondrial cytochrome b gene. I found significant geographic structure across the range of M broweri. The results of my analyses suggest a recent population expansion from central Alaska (Beringia) into the formerly glaciated Brooks Range
    • Distribution of hexachlorobenzene concentrations in spruce needle samples across Alaska

      Billings, Shane (2000-05)
      The global distribution of persistent organic pollutants has initiated considerable effort towards understanding long range atmospheric transport and partitioning of these potentially damaging compounds. Apparent latitude dependent concentration gradients of organic pollutants in otherwise pristine environments has given rise to a global fractionation model, coined the cold finger effect. According to the cold finger theory, semi-volatile persistent organic pollutant will show a preference for partitioning from the atmosphere to the ground and vegetation at northern latitudes. Here we present a study of hexachlorobenzene in spruce needle samples across Alaska, which offers a large range of climates, from its southern coastal rain forests to the northern arctic. The large variation in climate across Alaska should result in a measurable latitude dependent concentration gradient for HCB, if the cold finger effect is being realized. Spruce needle samples were extracted, cleaned, and analyzed by GC/MS. According to principle component regression analysis, HCB concentrations in all the spruce needle samples across Alaska show a strong positive correlation with lipid content of the needles. The HCB concentrations also show two distinct latitude trends. The spruce needle samples taken from the coast to approximately 63° north show relatively high HCB concentrations and a possible negative correlation with latitude. The samples between 63° and 68° north show a definite positive correlation between HCB concentration and latitude, which is consistent with the cold finger effect.
    • Distribution of hunter groups and environmental effects on moose harvest in Interior Alaska

      Hasbrouck, Tessa R.; Brinkman, Todd; Stout, Glenn; Kielland, Knut (2018-12)
      Moose (Alces alces) is one of the most valuable wild game resources in Interior Alaska. In recent years, residents of rural indigenous communities have expressed concern that climate change and competition from non-local hunters are challenging local moose harvest opportunities. I collaborated with wildlife agencies and village tribal councils to co-design two studies to address rural community hunter concerns. The first study assessed the spatial and temporal distribution of local and non-local hunter groups to examine areas of potential competition. The second study addressed changing environmental factors and their impacts on moose harvest. Although competition among local hunters or among non-local hunters certainly occurs, competition between local and non-local hunters, or between resident and non-resident hunters is a more common and reoccurring issue. Local hunters are those who hunt in the area in which they reside whereas non-local hunters travel away from the area they reside to hunt. I assessed hunting patterns by local and non-local hunters in a remote hunting region near the interior villages of Koyukuk and Nulato to quantify moose harvest overlap between these two user groups to assess potential competition. I used Alaska Department of Fish and Game (ADFG) moose harvest records to develop a relative competition index that identified locations and time periods within the hunting season where the greatest overlap occurred from 2000-2016. I determined that the highest competition occurred between 16-20 September (i.e., peak harvest period) and was concentrated predominantly along major rivers. To decrease overlap and mitigate potential competition between hunter groups we recommend providing information on competition hotspots to hunters, or lifting the no-fly regulation in the Koyukuk Controlled Use Area with the caveat that hunting with the use of aircraft must occur 1.6 km from the Koyukuk River corridor. These actions may provide hunters information on how to re-distribute themselves across the landscape and allow hunters to use areas away from rivers, where most harvest currently occurs. Additionally, climate change and seasonal variability have anecdotally been documented to impact moose hunting opportunities. Specifically, warm temperatures, delayed leaf drop, and fluctuating water levels are concerns expressed by some local hunters. I quantified changes in temperature, leaf drop, and water level near Koyukuk and Nulato and the subsequent relationships between these environmental variables and the total number of moose harvested using linear regression models. I used temperature data, gauging station data (i.e., water level), remote sensing data (i.e., leaf drop analysis), and ADFG moose harvest records and explored previously untested hypotheses and to quantify relationships from 2000-2016. I concluded that non-local hunter harvest success was more dependent than local harvest success on environmental conditions. Non-local harvest significantly increased with higher water levels from 6-10 Sept (p=0.02), 11-15 Sept (p=0.02), and 16-20 Sept (p<0.01), and decreased with warmer temperatures in the same three time periods (p<0.01, p=0.02, p<0.01, respectively). Local harvest increased with higher water levels from 16-20 Sept (p<0.01). These results quantitatively show that environmental factors do impact hunter success. I speculate that local hunter harvest success is less dependent on environmental variability because they have the ability to harvest opportunistically, rely more heavily on the resource, and reside near the hunting area. This ability to opportunistically hunt and adapt may give them an advantage over non-local hunters as environmental conditions shift with climate change.
    • Distribution of large calanoid copepods in relation to physical oceanographic conditions and foraging auklets in the western Aleutian Islands

      Coyle, Kenneth Orval (1997)
      Acoustic measurements and net sampling were used to estimate zooplankton abundance and biomass relative to water mass types and flow fields in the western Aleutian Islands during June and July, 1992 and 1993. Observations are interpreted relative to the distribution and abundance of least auklets (Aethia pusilla), which forage on zooplankton. Highest zooplankton biomass (up to 7 g m$\sp{-3}$) occurred during June 1992, in the pycnocline separating the upper mixed layer from the cold intermediate layer north of a front separating Bering Sea and Alaska Stream water. The large calanoid Neocalanus flemingeri had highest abundance but the larger Neocalanus cristatus accounted for most of the biomass. N. cristatus and N. flemingeri were absent south of the Bering Sea front, where the community was dominated by Neocalanus plumchrus and Eucalanus bungii. Auklets were foraging almost exclusively north of the Bering Sea front. Neocalanus spp. abundance in the upper mixed layer was much lower in July 1993, than in June 1992. Neocalanus occurred primarily in scattered aggregates near the pycnocline over Bering Sea Intermediate water and at the surface in Pacific water. Auklets shifted their foraging activities to passes and shelf areas among the islands, where tidally generated divergences and convergences upwelled and concentrated prey into patches in the mixed layer. Elevated densities of Neocalanus were observed in convergence zones in Delarov Pass and over a ridge south of Kiska Island. Convergence zones were identified by intense sound scattering from entrained bubbles and by deceleration of the horizontal velocity components in acoustic doppler current data, a record of current speed and direction beneath the vessel. Densities of auklet prey in the study area during June were apparently influenced by the position of the front between Bering Sea and Pacific water masses. The position of the front was influenced by Alaska Stream flow anomalies lasting for several years. Prey densities on the shelves and in the passes during July were influenced by tidal currents at spatial scales of tens of meters to ten kilometers and lasting one tidal cycle.
    • Distribution, Growth And Egg Production Of Euphausiids In The Northern Gulf Of Alaska

      Pinchuk, Alexei I.; Hopcroft, Russell (2006)
      The euphausiids Thysanoessa inermis, Thysanoessa spinifera and Euphausia pacifica are key pelagic grazers and important prey for many vertebrates in the Gulf of Alaska (GOA). This thesis provides the first account of distribution, egg production, growth, development, and temporal variability in abundance of the euphausiids in relation to environmental variations in the northern GOA. T. inermis and T spinifera were abundant on the shelf within 120-130 km from the coast, while E. pacifica originated from offshore and was advected onto the shelf during summer. E. pacifica produced multiple broods with brood size strongly related to ambient chlorophyll a concentrations. In contrast, T. inermis released eggs once in the season and its brood size did not depend on chlorophyll content. Early development of these species showed a remarkably similar response to changes in temperature. The highest molting increments were observed during the spring phytoplankton bloom for T. inermis, and in summer for T. spinifera and E. pacifica, suggesting coupling with food availability. The molting rates were strongly influenced by temperature. Growth rates depended on euphausiid size, and were close to 0 in early spring, reaching maximum values in May (0.123 mm d-1 or 0.023 d -1 for T. inermis) and July (0.091 mm d-1 or 0.031 d-1 for T. spinifera). The growth rates for E. pacifica remained below 0.07 mm d -1 (0.016 d-1) throughout the season. The relationship between T. inermis weight specific growth rate (adjusted to 5�C) and ambient chlorophyll-a concentration fit a Michaelis-Menten curve (r2=0.48), but such relationships were not significant for T. spinifera or E. pacifica. Reproduction of T. inermis occurred during April in 1998 and 2003, and was extended through May in 1999-2002. The spawning of T. inermis and T. spinifera was related to the spring diatom bloom on the inner shelf, while the spawning of E. pacifica occurred later in season, when the water temperature increased. A strong increase in abundance of T. inermis, associated with the extended colder phase in the North Pacific, indicates that progressive cooling in 1999-2002 may have resulted in greater reproductive success of early spawning T. inermis on the inner shelf.
    • Disturbance History In The Tanana River Basin Of Alaska: Management Implications

      Roessler, James S.; Packee, Edmond C. (1997)
      The forests of Tanana River Basin in Interior Alaska have a history of disturbance. Four issues reflecting forest disturbance, important to include in current management strategies for these lands, were researched: (1) disturbance history of the Tanana Valley; (2) Alaska Interagency Fire Management Plan: a case study; (3) prescribed natural fire in Alaska: possibilities and complexities; and (4) past use of prescribed fire in white spruce: a summary with particular reference to Alaska. Through researching historical archives, conducting field visits, interviewing land and fire managers and reviewing current planning documents, I reached four major conclusions: (1) there is lack of use of historical facts regarding human-induced changes on the landscapes; (2) past involvement of public stakeholders in fire planning in Alaska was inadequate; (3) the Alaska Interagency Fire Management Plans need to identify scientific prescription parameters which address specific land management objectives; and (4) management-ignited prescribed fire must become a more common prescription after harvesting of white spruce. <p>
    • Divergence, gene flow, and the speciation continuum in trans-Beringian birds

      McLaughlin, Jessica F.; Winker, Kevin; Takebayashi, Naoki; Hundertmark, Chris (2017-08)
      Understanding the processes of divergence and speciation, particularly in the presence of gene flow, is key to understanding the generation of biodiversity. I investigated divergence and gene flow in nine lineages of birds with a trans-Beringian distribution, including pairs of populations, subspecies, and species, using loci containing ultraconserved elements (UCEs). I found that although these lineages spanned conditions from panmixia to fully biologically isolated species, they were not smoothly distributed across this continuum, but formed two discontinuous groups: relatively shallow splits with gene flow between Asian and North American populations, no fixed SNPs, and lower divergence; and relatively deeply split lineages with multiple fixed SNPs, higher divergence, and relatively low rates of gene flow. All eight lineages in which two populations were distinguishable shared the same divergence model, one with gene flow without a prolonged period of isolation. This was despite the diversity of lineages included that might not have responded in the same ways to the glacial-interglacial cycles of connection and isolation in Beringia. Together, these results highlight the role of gene flow in influencing divergence in these Beringian lineages. Sample size is a critical aspect of study design in population genomics research, yet few empirical studies have examined the impacts of small sample sizes. Using split-migration models optimized with full datasets, I subsampled the datasets from Chapter 1 at sequentially smaller sample sizes from full datasets of 6 - 8 diploid individuals per population and then compared parameter estimates and their variances. Effective population size parameters (ν) tended to be underestimated at low sample sizes (fewer than 3 diploid individuals per population), migration (m) was fairly reliably estimated until under 2 individuals per population, and no trend of over- or underestimation was found in either time since divergence (T) or Θ (4Nrefμ) . Lineages that were split above the population level (subspecies and species pairs) tended to have lower variance at smaller sample sizes than population-level splits, with many parameters reliably estimated at levels as low as 3 diploid individuals per population, whereas shallower splits (i.e., populations) often required at least 5 individuals per population for reliable demographic inferences. Although divergence levels may be unknown at the outset of study design, my results provide a framework for planning appropriate sampling, and for interpreting results if smaller sample sizes must be used.
    • Diversification of the fern genus Cryptogramma across time and space

      Metzgar, Jordan S.; Ickert-Bond, Stefanie; Wolf, Diana; Windham, Michael; Takebayashi, Naoki; Pryer, Kathleen (2016-05)
      I examined diversification, biogeographic history and polyploidy within the parsley ferns (Cryptogramma) across multiple time scales. Cryptogramma is a small circumboreal genus of rock ferns in the large, diverse family Pteridaceae and is most closely related to the Asian genus Coniogramme and the monotypic Central American genus Llavea. I generated a combined six locus plastid sequence alignment (rbcL, rbcL-accD, rbcL-atpB, rps4-trnS, trnG-trnR, and trnPpetG) and a low-copy nuclear marker (gapCp) alignment for 40 accessions. Phylogenetic analysis of these datasets using maximum parsimony, maximum likelihood, and Bayesian inference demonstrate that all three genera are reciprocally monophyletic, with Cryptogramma and Coniogramme most closely related to one another. This analysis also recovered the monotypic Cryptogramma section Homopteris and sect. Cryptogramma as reciprocally monophyletic. Within sect. Cryptogramma, the unambiguously supported phylogeny supported recognizing most described species as reciprocally monophyletic clades that are mostly allopatric and can be delineated by a few morphological characters. The nuclear DNA phylogeny supported the hypothesis that the allotetraploid Cr. sitchensis originated from a hybridization event between the Asian Cr. raddeana and the Beringian Cr. acrostichoides, and the plastid DNA phylogeny revealed that Cr. acrostichoides was the maternal parent. In contrast, the tetraploid Cr. crispa appears to have originated as an autopolyploid from an undiscovered or extinct ancestor. Further phylogenetic investigation of European Cryptogramma species using DNA sequence data from 15 accessions from Europe and southwest Asia revealed that Pleistocene glacial cycles have created genetic partitioning of Cr. crispa into eastern and western clades and have also led to the formation of the Turkish auto-octoploid Cr. bithynica with Cr. crispa as the parental taxon. Divergence time estimates for key nodes were inferred using Bayesian analysis of the plastid data set coupled with secondary time constraints to reveal that crown group Cryptogramma began diversifying in the Oligocene, with most present-day species originating in the Pliocene and Pleistocene. The genus was inferred by likelihood-based ancestral area reconstruction of the chronogram and geographic distribution data to have originated in east Asia, with four colonization events reconstructed by vicariance or dispersal to the New World. My Bayesian Analysis of Macroevolutionary Mixtures (BAMM) showed no significant difference in speciation rates across time or among clades. The morphological stasis of Cryptogramma and its stable speciation rates in response to climate cycles during the Pleistocene suggest it will survive future range shifts caused by anthropogenically induced climate change.
    • Diversity and community structure of eukaryotic phototrophs in the Bering and Chukchi seas

      Lekanoff, Rachel M.; Collins, R. Eric; McDonnell, Andrew M.P.; Danielson, Seth L. (2020-05)
      The phytoplankton of the Bering and Chukchi seas support highly productive ecosystems characterized by tight benthic-pelagic coupling. In this study, we focus on the northern Bering and Chukchi seas, considering them as one ecosystem. This community has historically been dominated by diatoms; however, climate change and accompanying warming ocean temperatures may alter primary producer communities. Using metabarcoding, we present the first synoptic, high-throughput molecular phylogenetic investigation of phytoplankton diversity in the Bering and Chukchi seas based on hundreds of samples collected from June to September in 2017. We identify the major and minor taxonomic groups of diatoms and picophytoplankton, relative abundances of genera, exact sequence variants (201 for diatoms and 227 for picophytoplankton), and describe their biogeography. These phylogenetic insights and environmental data are used to characterize preferred temperature ranges, offering insight into which specific phytoplankton (Chaetoceros, Pseudo−nitzschia, Micromonas, Phaeocystis) may be most affected as the region warms. Finally, we investigated the likelihood of using shipboard CTD data alone as predictive variables for which members of phytoplankton communities may be present. We found that the suite of environmental data collected from a shipboard CTD is a poor predictor of community composition, explaining only 12.6% of variability within diatom genera and 14.2% variability within picophytoplankton genera. Clustering these communities by similarity of samples did improve predictability (43.6% for diatoms and 32.5% for picophytoplankton). However, our analyses succeeded in identifying temperature as a key driver for certain taxa found commonly throughout the region, offering a key insight into which common phytoplankton community members may be affected first as the Alaskan Arctic continues to warm.
    • Diversity In The Boreal Forest Of Alaska: Distribution And Impacts On Ecosystem Services

      Young, Brian D.; Yarie, John; Chapin, F. Stuart; Greenburg, Josh; Huettmann, Falk; Verbyla, David (2012)
      Within the forest management community, diversity is often considered as simply a list of species present at a location. In this study, diversity refers to species richness and evenness and takes into account vegetation structure (i.e. size, density, and complexity) that characterize a given forest ecosystem and can typically be measured using existing forest inventories. Within interior Alaska the largest forest inventories are the Cooperative Alaska Forest Inventory and the Wainwright Forest Inventory. The limited distribution of these inventories constrains the predictions that can be made. In this thesis, I examine forest diversity in three distinct frameworks; Recruitment, Patterns, and Production. In Chapter 1, I explore forest management decisions that may shape forest diversity and its role and impacts in the boreal forest. In Chapter 2, I evaluate and map the relationships between recruitment and species and tree size diversity using a geospatial approach. My results show a consistent positive relationship between recruitment and species diversity and a general negative relationship between recruitment and tree size diversity, indicating a tradeoff between species diversity and tree size diversity in their effects on recruitment. In Chapter 3, I modeled and mapped current and possible future forest diversity patterns within the boreal forest of Alaska using machine learning. The results indicate that the geographic patterns of the two diversity measures differ greatly for both current conditions and future scenarios and that these are more strongly influenced by human impacts than by ecological factors. In Chapter 4, I developed a method for mapping and predicting forest biomass for the boreal forest of interior Alaska using three different machine-learning techniques. I developed first time high resolution prediction maps at a 1 km2 pixel size for aboveground woody biomass. My results indicate that the geographic patterns of biomass are strongly influenced by the tree size class diversity of a given stand. Finally, in Chapter 5, I argue that the methods and results developed for this dissertation can aid in our understanding of forest ecology and forest management decisions within the boreal region.
    • Diversity, abundance and fate of ice algae and phytoplankton in the Bering Sea

      Szymanski, Anna; Gradinger, Rolf; Iken, Katrin; Collins, R. Eric (2014-12)
      Sea ice algae are an essential part of Arctic and subarctic ecosystems. They significantly contribute to total algal primary production, serve as an early spring food source for both pelagic and benthic biota, and can seed the spring phytoplankton bloom during periods of ice melt. In the subarctic Bering Sea, virtually nothing has been known about the composition of the ice algal community, its magnitude, and its connection to pelagic and benthic ecosystems. This study, therefore, focused on the diversity, abundance, and ultimate fate of ice algae in the Bering Sea using sea ice, water and sub-ice sediment trap samples collected during two spring periods: ice growth (March to mid-April) and ice melt (mid-April to May) in 2008 and 2009. Ice algal species composition was comparable to those in Arctic regions. The phytoplankton species inventory was similar to that found in the overlying ice, suggesting that the spring phytoplankton were seeded from the ice algae. Algal abundance in the ice was on average three orders of magnitude higher than in the water column throughout both periods, as the extensive Bering Sea ice cover in 2008-2009 delayed the phytoplankton bloom. There was a substantial increase in the vertical flux of algal cells beneath the ice during the period of ice melt, but measurable amounts appeared as early as mid-March. The majority of this flux was composed of healthy algal cells, making it a rich food source for benthic organisms. Differences in the relative species composition between ice and trap samples indicate that algal fate was influenced by the species specific sinking rate of algal cells, among other factors, in the water column. In conclusion, ice algae in the Bering Sea are diverse and abundant, and contribute to both pelagic and benthic systems.
    • Diving physiology of the ringed seal: adaptations, capability and implications

      Ferren, Howard Jennings (1980-08)
      Adaptations that influence duration of diving in the ringed seal, Phoaa (Pusa) hispida were examined. Mean blood volume was 234 ml/kg lean body mass (LBM) and oxygen capacity was 30.7 ml O2/100 ml of whole blood, yielding a total blood oxygen capacity of 70 ml O2/kg LBM. Abrupt and prolonged bradycardia occurred upon submersion. Experimental dives indicated submersion durations of up to 18 minutes before the onset of physiological dysfunction. The percentage of LBM represented by the brain is least in the relatively large Weddell seal (0.2%), greater in the harbor seal (0.7%) (the compared species) and greatest in the ringed seal (1.4%); this sets the requirement for minimum obligatory oxygen consumption. The differences observed in diving durations between the three species is considered to be mainly the consequence of brain/body size relationship.
    • Division of parental roles in the monogamous western sandpiper, Calidris mauri

      Neville, Juliette Aimee (2002-05)
      I investigated whether male and female Western Sandpipers (Calidris mauri) contributed equal amounts of parental care during the breeding season, near Nome, AK, USA (64 ̊N) during 1998 and 1999. I repeatedly observed which parent was present at the nest during incubation and which parent tended the brood during the brood care period. Females incubated predominantly at night (18:00-06:00 hr ADT); males incubated predominantly during the day (06:00-18:00 hr ADT). Males spent more time incubating than females (57% vs. 43%, P<0.05). Females deserted their broods on average 5.6 days after hatch, while males tended broods on average 13.0 days after hatch (P<0.001). Nests that hatched earlier in the season received significantly more bi-parental care during the brood care period (P=0.01). Timing of nest initiation had the greatest effect on the division of parental care between sexes for Western Sandpipers.
    • DNA mismatch repair at an oncogenic hotspot correlated with phase of the cell cycle and environmentally relevant concentrations of the Arctic pollutant p, p'-DDE

      Simonetti, Josephine (2001-05)
      Part I: Mismatch repair in G₁ synchronized mammalian cells. Deficiencies in DNA mismatch repair have been found in hereditary nonpolyposis colon cancer (HNPCC), as well as in sporadic cancers, illustrating the importance of this single repair system in maintaining genomic integrity. In bacteria, this repair system functions primarily, after DNA replication, in the correction of polymerase base insertion errors and in mammalian cells it was also assumed that the mismatch repair system functioned within a similar timeframe. However, DNA mismatches occur ubiquitously and their repair before DNA replication is of paramount importance for faithful genome copying. We investigated the activity of the mismatch repair system, in G₁ synchronized NIH 3T3 cells, in the repair of four mismatches at an oncogenic hotspot in the H-ras gene. Our results clearly show that the mismatch repair system is active and accurate during the pre-replicative G₁ phase of the mammalian cell cycle. Part II: Effects of p, p'-DDE on cell toxicity and DNA mismatch repair ability. Umbilical cord blood, from Inupiat infants in Barrow Alaska, was examined for the presence of several environmental contaminants. All 24 blood samples analyzed contained measurable levels of p, p'-DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene) with an average concentration of 0.33 ug/1. We examined whether this low concentration of p, p'-DDE had detectable effects on NIH 3T3 (mouse embryonic) and WS1 (human fetal) cells in culture. Initial experiments indicated that exposure to p, p'-DDE resulted in a decrease in the cell number of both cell types. Subsequent analysis revealed that this decrease was due to cell death in NIH 3T3 cells and to cell cycle arrest in WS1 cells. We also examined the effect of p, p'-DDE on the ability of both cell types to repair mismatches at an oncogenic hotspot in H-ras. Preliminary results indicate that p, p'-DDE does not have a discernable effect on the ability of either cell type to correctly repair the G:T mismatch. However, p, p'-DDE exposure results in an increased rate of correct repair of the G:A mismatch by both cell types. Overall, this study demonstrates that p, p'-DDE, at concentrations relevant to the Alaskan environment has significantn but different effects on two immature cell types in culture.