From Forest To Tundra: Historical Biogeography, Floristic Diversity And Nucleotide Variation In Balsam Poplar

Thesis (Ph.D.) University of Alaska Fairbanks, 2010The North America boreal forest extends across more than 10� of latitude from central Labrador to interior Alaska. Periods of major climate fluctuations, including glacial and interglacial cycles, drove major migrations in the Quaternary history of the boreal forest. Beringia, the unglaciated region between the Lena and Mackenzie rivers, is recognized as an important refugium for arctic plants during the last ice age, but its role for boreal trees remains controversial. The paleobotanical record indicates Populus balsamifera (balsam poplar) survived within Beringia during the last glacial. My research employed an interdisciplinary approach, combining techniques in the fields of ecology, evolution and population genetics, to reconstruct the late Quaternary migration history of balsam poplar and to describe and classify balsam poplar plant communities in the Alaskan Arctic. Chapter 1 describes the motivation for the research. Chapter 2 addresses whether a demographically-detectable population of balsam poplar was present within Beringia during the most recent ice age. I found that patterns of variation in chloroplast DNA are most consistent with the presence of a single population of balsam poplar south of the continental ice sheets through the Late Quaternary. Chapter 3 is an analysis of floristic diversity in balsam poplar communities across the Arctic Slope, Interior Alaska and the Yukon Territory and asks whether one balsam poplar-associated plant community spans the arctic and boreal regions, or if these communities differ. I found that arctic communities are dominated by arctic-alpine taxa, whereas boreal communities are dominated by boreal taxa. A strong linkage between climate and the occurrence of balsam poplar also was observed on the Arctic Slope. Chapter 4 is a study of nucleotide diversity in three nuclear loci across the range of balsam poplar. This was the first study to document geographic structure in genetic variation within the species. It also showed that diversity in three North American poplars (P. balsamifera, P. deltoides and P. trichocarpa) was substantially less than that of three Eurasian poplars (P. alba, P. nigra and P. tremula). Chapter 5 summarizes the research and points toward future research directions

Remote sensing-based statistical approach for defining drained lake basins in a continuous Permafrost region, North Slope of Alaska

Lake formation and drainage are pervasive phenomena in permafrost regions. Drained lake basins (DLBs) are often the most common landforms in lowland permafrost regions in the Arctic (50% to 75% of the landscape). However, detailed assessments of DLB distribution and abundance are limited. In this study, we present a novel and scalable remote sensing-based approach to identifying DLBs in lowland permafrost regions, using the North Slope of Alaska as a case study. We validated this first North Slope-wide DLB data product against several previously published sub-regional scale datasets and manually classified points. The study area covered \u3e71,000 km2, including a \u3e39,000 km2 area not previously covered in existing DLB datasets. Our approach used Landsat-8 multispectral imagery and ArcticDEM data to derive a pixel-by-pixel statistical assessment of likelihood of DLB occurrence in sub-regions with different permafrost and periglacial landscape conditions, as well as to quantify aerial coverage of DLBs on the North Slope of Alaska. The results were consistent with previously published regional DLB datasets (up to 87% agreement) and showed high agreement with manually classified random points (64.4–95.5% for DLB and 83.2– 95.4% for non-DLB areas). Validation of the remote sensing-based statistical approach on the North Slope of Alaska indicated that it may be possible to extend this methodology to conduct a comprehensive assessment of DLBs in pan-Arctic lowland permafrost regions. Better resolution of the spatial distribution of DLBs in lowland permafrost regions is important for quantitative studies on landscape diversity, wildlife habitat, permafrost, hydrology, geotechnical conditions, and high-lat-itude carbon cycling

Arctic tundra shrubification: a review of mechanisms and impacts on ecosystem carbon balance

Vegetation composition shifts, and in particular, shrub expansion across the Arctic tundra are some of the most important and widely observed responses of high-latitude ecosystems to rapid climate warming. These changes in vegetation potentially alter ecosystem carbon balances by affecting a complex set of soil-plant-atmosphere interactions. In this review, we synthesize the literature on (a) observed shrub expansion, (b) key climatic and environmental controls and mechanisms that affect shrub expansion, (c) impacts of shrub expansion on ecosystem carbon balance, and (d) research gaps and future directions to improve process representations in land models. A broad range of evidence, including in-situ observations, warming experiments, and remotely sensed vegetation indices have shown increases in growth and abundance of woody plants, particularly tall deciduous shrubs, and advancing shrublines across the circumpolar Arctic. This recent shrub expansion is affected by several interacting factors including climate warming, accelerated nutrient cycling, changing disturbance regimes, and local variation in topography and hydrology. Under warmer conditions, tall deciduous shrubs can be more competitive than other plant functional types in tundra ecosystems because of their taller maximum canopy heights and often dense canopy structure. Competitive abilities of tall deciduous shrubs vs herbaceous plants are also controlled by variation in traits that affect carbon and nutrient investments and retention strategies in leaves, stems, and roots. Overall, shrub expansion may affect tundra carbon balances by enhancing ecosystem carbon uptake and altering ecosystem respiration, and through complex feedback mechanisms that affect snowpack dynamics, permafrost degradation, surface energy balance, and litter inputs. Observed and projected tall deciduous shrub expansion and the subsequent effects on surface energy and carbon balances may alter feedbacks to the climate system. Land models, including those integrated in Earth System Models, need to account for differences in plant traits that control competitive interactions to accurately predict decadal- to centennial-scale tundra vegetation and carbon dynamics

Concentrated, non-foaming solution of quaternary ammonium compounds and methods of use

A concentrated quaternary ammonium compound (QAC) solution with a concentration from greater than about 10% by weight and at least one solubility enhancing agent, such as an alcohol, is disclosed. A diluted QAC solution is used to contact food products to prevent microbial growth on the food products from a broad spectrum of foodborne microbial contamination. A method of contacting the food products with the dilute QAC for an application time of at least 0.1 second is disclosed. The foods that can be treated by this method are meat and meat products, seafood, vegetables, fruit, dairy products, pet foods and snacks, and any other food that can be treated and still retain its appearance and texture. One of the treatment methods is spraying and misting the QAC solutions on the food products for an application time of at least 0.1 second to prevent broad spectrum foodborne microbial contamination

Concentrated, non-foaming solution of quaternary ammonium compounds and methods of use

A concentrated quaternary ammonium compound (QAC) solution with a concentration greater than about 10% by weight and at least one solubility enhancing agent, such as an alcohol, is disclosed. A diluted QAC solution is useful on food products to prevent microbial growth on the food from a broad spectrum of foodborne microbial contamination. Also disclosed is a method of contacting food products with the dilute QAC for an application time of at least 0.1 second. Foods that can be treated by this method are meat and meat products, seafood, vegetables, fruit, dairy products, pet foods and snacks, and any other food that can be treated and still retain its appearance and texture. One of the treatment methods is spraying and misting the QAC solutions on the food products for an application time of at least 0.1 second to prevent broad spectrum foodborne microbial contamination

Concentrated, non-foaming solution of quaternary ammonium compounds and methods of use

A concentrated quaternary ammonium compound (QAC) solution with a concentration from greater than about 10% by weight and at least one solubility enhancing agent, such as an alcohol, is disclosed. A diluted QAC solution is used to contact food products to prevent microbial growth on the food products from a broad spectrum of foodborne microbial contamination. A method of contacting the food products with the dilute QAC for an application time of at least 0.1 second is disclosed. The foods that can be treated by this method are meat and meat products, seafood, vegetables, fruit, dairy products, pet foods and snacks, and any other food that can be treated and still retain its appearance and texture. One of the treatment methods is spraying and misting the QAC solutions on the food products for an application time of at least 0.1 second to prevent broad spectrum foodborne microbial contamination

A holistic and comprensive data approach validates the distribution of the critically endangered flapper skate (Dipturus intermedius)

Morphological similarities between skates of the genus Dipturus in the north-eastern Atlantic and mediterranean have resulted in longstanding confusion, misidentification and misreporting. Current evidence indicates that the common skate is best explained as two species, the flapper skate (Dipturus intermedius) and the common blue skate (D. batis). However, some management and conservation initiatives developed prior to the separation continue to refer to common skate (as ‘D. batis’). This taxonomic uncertainty can lead to errors in estimating population viability, distribution range, and impact on fisheries management and conservation status. Here, we demonstrate how a concerted taxonomic approach, using molecular data and a combination of survey, angler and fisheries data, in addition to expert witness statements, can be used to build a higher resolution picture of the current distribution of D. intermedius. Collated data indicate that flapper skate has a more constrained distribution compared to the perceived distribution of the ‘common skate’, with most observations recorded from Norway and the western and northern seaboards of Ireland and Scotland, with occasional specimens from Portugal and the Azores. Overall, the revised spatial distribution of D. intermedius has significantly reduced the extant range of the species, indicating a possibly fragmented distribution range.acceptedVersio

The Alaska Arctic Vegetation Archive (AVA-AK)

The Alaska Arctic Vegetation Archive (AVA-AK, GIVD-ID: NA-US-014) is a free, publically available database archive of vegetation-plot data from the Arctic tundra region of northern Alaska. The archive currently contains 24 datasets with 3,026 non-overlapping plots. Of these, 74% have geolocation data with 25-m or better precision. Species cover data and header data are stored in a Turboveg database. A standardized Pan Arctic Species List provides a consistent nomenclature for vascular plants, bryophytes, and lichens in the archive. A web-based online Alaska Arctic Geoecological Atlas (AGA-AK) allows viewing and downloading the species data in a variety of formats, and provides access to a wide variety of ancillary data. We conducted a preliminary cluster analysis of the first 16 datasets (1,613 plots) to examine how the spectrum of derived clusters is related to the suite of datasets, habitat types, and environmental gradients. Here, we present the contents of the archive, assess its strengths and weaknesses, and provide three supplementary files that include the data dictionary, a list of habitat types, an overview of the datasets, and details of the cluster analysis

Common schizophrenia alleles are enriched in mutation-intolerant genes and maintained by background selection

Schizophrenia is a debilitating psychiatric condition often associated with poor quality of life and decreased life expectancy. Lack of progress in improving treatment outcomes has been attributed to limited knowledge of the underlying biology, although large-scale genomic studies have begun to provide such insight. We report the largest single cohort genome-wide association study of schizophrenia (11,260 cases and 24,542 controls) and through meta-analysis with existing data we identify 50 novel GWAS loci. Using gene-wide association statistics we implicate an additional set of 22 novel associations that map onto a single gene. We show for the first time that the common variant association signal is highly enriched among genes that are intolerant to loss of function mutations and that variants in these genes persist in the population despite the low fecundity associated with the disorder through the process of background selection. Associations point to novel areas of biology (e.g. metabotropic GABA-B signalling and acetyl cholinesterase), reinforce those implicated in earlier GWAS studies (e.g. calcium channel function), converge with earlier rare variants studies (e.g. NRXN1, GABAergic signalling), identify novel overlaps with autism (e.g. RBFOX1, FOXP1, FOXG1), and support early controversial candidate gene hypotheses (e.g. ERBB4 implicating neuregulin signalling). We also demonstrate the involvement of six independent central nervous system functional gene sets in schizophrenia pathophysiology. These findings provide novel insights into the biology and genetic architecture of schizophrenia, highlight the importance of mutation intolerant genes and suggest a mechanism by which common risk variants are maintained in the population

Leucine-enriched protein feeding does not impair exercise-induced free fatty acid availability and lipid oxidation: beneficial implications for training in carbohydrate-restricted states

Given that the enhanced oxidative adaptations observed when training in carbohydrate (CHO) restricted states are potentially regulated through free fatty acid (FFA) mediated signalling and that leucine rich protein elevates muscle protein synthesis, the present study aimed to test the hypothesis that leucine enriched protein feeding enhances circulating leucine concentration but does not impair FFA availability nor whole body lipid oxidation 56 during exercise. Nine males cycled for 2 h at 70% VO2peak when fasted (PLACEBO) or having consumed a whey protein solution (WHEY) or a leucine enriched whey protein gel (GEL), administered as 22 g 1 hour pre-exercise, 11 g/h during and 22 g thirty minutes post-exercise. Total leucine administration was 14.4 g and 6.3 in GEL and WHEY, respectively. Mean plasma leucine concentrations were elevated in GEL (P= 0.001) compared 60 with WHEY and PLACEBO (375 ± 100, 272 ± 51, 146 ± 14 μmol.L-1 respectively). No differences (P= 0.153) in plasma FFA (WHEY 0.53 ± 0.30, GEL 0.45 ± 0.25, PLACEBO 0.65 ± 0.30, mmol.L-1) or whole body lipid oxidation during exercise (WHEY 0.37 ± 0.26, GEL 0.36 ± 0.24, PLACEBO 0.34 ± 0.24 g/min) were apparent between trials, despite elevated (P= 0.001) insulin in WHEY and GEL compared with PLACEBO (38 ± 16, 35 ± 16, 22 ± 11 pmol.L-1 respectively). We conclude that leucine enriched protein feeding does not impair FFA availability nor whole body lipid oxidation during exercise, thus having practical applications for athletes who deliberately train in CHO restricted states to promote skeletal muscle adaptations