Molecular and morphological perspectives on post-glacial colonization of Clethrionomys rutilus and Clethrionomys gapperi in Southeast Alaska

Thesis (M.S.) University of Alaska Fairbanks, 2001Pleistocene events had a significant impact on the geographic distributions of high latitude organisms. Recently deglaciated, Southeast Alaska has been colonized by two species of red-backed voles, clethrionomys rutilus and C. gapperi. With distinct biogeographic histories, post-glacial colonization of C. rutilus and C. gapperi into this region would have occurred by different routes. Variation in the mitochondrial cytochrome b gene, the MYH2 nuclear intron, and the post palatal bridge were assessed to examine phylogeographic patterns of these two species, and a proposed contact zone in southeast Alaska. Low, but consistent, levels of sequence divergence of the cytochrome b gene were found among four endemic populations, which corresponded with the complex topography of southeast Alaska. Asymmetrical introgression of the mitochondrial genome diagnostic of C. rutilus was observed in C. gapperi. Post glacial contact resulting from the retreat of the Cordilleran and Laurentide ice sheets has apparently led to the formation of this hybrid zone

Phylogeography of Southern Red-Backed Voles in North America

Climate change has altered species distributions and has lead to species forming as they I ive in isolated refugia. I propose to examine microsatl I ite alleles from the southern red-backed vole (Myodes gapperi) in order to test whether or not previously identified distinct I ineages of these voles can interbreed. If they are no longer interbreeding, this wi I I give us insight on how climate change can affect species distributions and contribute to speciation

Hemoglobin Sequences of the Painted Turtle

Through evolution, hemoglobin oxygen affinity has been altered in species that live in different environments. Hemoglobin is the blood protein that carries O2 from the lungs to the tissues, and returns CO2 (from the tissues) to the lungs. Members of the family Testudinidae (turtles and tortoises) live under different environmental conditions and thus experience different oxygen levels. The hemoglobin of adult turtles is comprised of α- globin (alpha-D and alpha-A) and β-globin. For this research, hemoglobin of the terrestrial African spurred tortoise (Geochelone sulcata) and the aquatic painted turtle (Chrysemys picta) were analyzed. The African spurred tortoise lives in the hot, arid environments such as the Sahara, while the painted turtle live in calm freshwater environments, with muddy water bottoms. Analyses of the hemoglobin proteins were done through reverse-transcriptase polymerase chain reaction (RT-PCR) using primers designed for turtle globin genes. PCR products were then cloned and grown on selective media, and sequenced. Sequences were translated into amino acids and analyses were conducted to determine if differences in particular amino acid residues could be important in affecting the oxygen affinity of the hemoglobin protein

Under graduate Curriculum Integration: Bringing Students Together Through Research

At Georgia Gwinnett College we are integrating the undergraduate educational experience for our Bachelor of Science students in the Biology discipline. We are using the opportunities presented by the genetic information revolution to combine biology courses in a longitudinal and integrative research project aimed at cataloguing biological diversity over space and time on the developing Georgia Gwinnett College campus

Vergleich zwischen ungeschädigter und ARDS-Lunge im Hinblick auf statische und dynamische Atemmechanik : eine experimentelle Studie an kontrolliert beatmeten Ratten

Zielsetzung: In der vorliegenden Arbeit sollte die nichtlineare Atemmechanik mit dynamischen und statischen Atemmanövern bei lungengesunden Ratten und Ratten mit pulmonalem ARDS untersucht werden. Insbesondere interessierte dabei der zeitliche Verlauf der atemmechanischen Veränderungen und das Auftreten eines sogenannten „Memory-Effektes“. Methodik: Die Studie bestand aus 2 Versuchsgruppen mit jeweils 22 Wistar-Ratten. Bei einer Gruppe (ARDS-Gruppe) wurde durch bronchioalveoläre Lavage mit 0,9%iger NaCl-Lösung ein ARDS induziert. Die andere Gruppe diente als lungengesunde Kontrollgruppe. Jeweils vor, sowie stündlich nach der Depletion des Surfactants in der ARDS-Gruppe und entsprechend analog in der Kontrollgruppe, wurde eine Analyse der statischen und dynamischen Atemmechanik sowie eine Blutgasanalyse vorgenommen und der mittlere arterielle Druck protokolliert. Die Atemmechanikmessung bestand aus 4 Konstantflussmanövern, einem Sinusfluss-Manöver, zwei aufeinanderfolgenden Low-Flow-Manövern sowie einem weiteren Sinusfluss-Manöver. Hauptergebnisse: In der ARDS-Gruppe kam es nach Schädigung zu einem deutlichen Abfallen der dynamischen Compliance. Die PV-Kurven der Low-Flow-Manöver unterschieden sich in der ARDS- und Kontrollgruppe. Während in der ARDS-Gruppe beide aufeinanderfolgende PV-Kurven bauchig waren, wies in der Kontrollgruppe nur die erste der beiden PV-Kurven ein „Knie“ im Sinne eines Druckbereiches innerhalb dessen Alveolen rekrutiert werden auf. In der Kontrollgruppe führten die beiden Low-Flow-Manöver zu einem Anstieg der dynamischen Compliance. In der ARDS-Gruppe kam es durch die Manöver nicht zu einer Complianceerhöhung. Ein Vergleich des während normaler Beatmung unmittelbar vor den Low-Flow-Manövern erreichten Plateaudrucks mit der Lokalisation des „Knies“ auf dem Inspirationsschenkel des ersten Low Flow-Manövers ergab, dass der Plateaudruck in der Kontrollgruppe unterhalb des Druckwertes des „Knies“ blieb, während die Plateaudrücke in der ARDS-Gruppe oberhalb des „Knies“ lagen. Nach Lavage kam es zu einem deutlichen Abfallen des arteriellen Sauerstoffpartialdruckes und des mittleren arteriellen Druckes. Der arterielle pH-Wert lag in der ARDS-Gruppe niedriger als in der Kontrollgruppe. Konklusion: Die bronchioalveoläre Lavage führt zu einer deutlichen Schädigung der Lunge. Während in der Kontrollgruppe Rekrutierungsmanöver zu einer anhaltenden Steigerung der Compliance führen, bleiben Rekrutierungsmanöver in der ARDS-Gruppe ohne Wirkung.Objectives: In this study we measured respiratory mechanics in healthy an injured lungs, using a saline lavage model. Respiratory mechanics were analyzed using dynamic and quasi-static maneuvers. The attention was turned mainly on possible memory effects of the lung and alterations of respiratory mechanics over the time. Methods: The study consisted of two groups each containing 22 female Wistar rats. One group received bronchoalveolar lavage with physiological saline (ARDS group). In the control group the lungs remained uninjured. Respiratory mechanics measurements and blood gas analysis were performed before injury and hourly after injury in the ARDS group and at the corresponding point of time in the control group. Arterial pressure was noted down at the same time. Measurements of respiratory mechanics consisted of 4 constant flow maneuvers, a sinusoidal flow maneuver, two low flow maneuvers and another sinusoidal flow maneuver. Main results: Dynamic compliance declined after saline lavage. The low flow pv-loops differed considerably between ARDS group and the control group. While in the ARDS group both of the consecutive loops where bellied, in the control group only the first loop showed a pronounced “knee” which faded or disappeared in the second loop. In the control group recruitment maneuvers resulted in an increase of dynamic compliance. This was not observable in the ARDS group. A comparison between the plateau pressure that was reached during tidal ventilation immediately before the low flow maneuvers showed that in the control group the plateau pressure was lower then the pressure on the localization of the “knee”, while in the ARDS group the plateau pressure exceeded the pressure corresponding to the “knee”. After lung injury arterial pO2 and arterial pressure declined. Blood pH was lower in the ARDS group than in the control group. Conclusion: Saline lavage leads to severe lung injury. While in the control group recruitment maneuvers led to an increase in dynamic compliance, recruitment maneuvers had no effect in injured lungs

Historic hybridization and persistence of a novel mito-nuclear combination in red-backed voles (genus Myodes)

<p>Abstract</p> <p>Background</p> <p>The role of hybridization in generating diversity in animals is an active area of discovery and debate. We assess hybridization across a contact zone of northern (<it>Myodes rutilus</it>) and southern (<it>M. gapperi</it>) red-backed voles using variation in skeletal features and both mitochondrial and nuclear loci. This transect extends approximately 550 km along the North Pacific Coast of North America and encompasses 26 populations (n = 485). We establish the history, geographic extent and directionality of hybridization, determine whether hybridization is ongoing, and assess the evolutionary stability of novel genomic combinations.</p> <p>Results</p> <p>Identification of <it>M. rutilus </it>and <it>M. gapperi </it>based on the degree of closure of the post-palatal bridge was concordant with the distribution of diagnostic nuclear MYH6 alleles; however, an 80 km zone of introgressed populations was identified. The introgressant form is characterized by having mitochondrial haplotypes closely related to the northern <it>M. rutilus </it>on a nuclear background and morphological characteristics of southern <it>M. gapperi</it>.</p> <p>Conclusion</p> <p>Introgression appears to have been historic as pure populations of <it>M. rutilus </it>are now isolated to the north from introgressants or pure <it>M. gapperi </it>by the LeConte Glacier. As we do not find pure <it>M. rutilus </it>or <it>M. gapperi </it>individuals throughout the distribution of the introgressant form, it appears that the introgressants are a self-sustaining entity not requiring continued hybridization between pure parental forms to generate this novel combination of characters.</p

Sensitivity of boreal forest carbon dynamics to long-term (1989-2005) throughfall exclusion in Interior Alaska)

Thesis (M.S.) University of Alaska Fairbanks, 2008"The objective of this study was to assess the effect of throughfall exclusion (1989-2005) on forest vegetation and soil in upland and floodplain landscape positions. In uplands, imposed drought reduced soil moisture at 5, 10, and 20 cm depths and increased soil C storage by slowing decomposer activity at the surface. In the drought plots, aboveground tree growth was reduced and root biomass in mineral soil was increased. In floodplains, imposed drought did not reduce soil moisture as strongly as it did in uplands, though near-surface soil C storage was still increased as a result of reduced decomposer activity. Floodplain vegetation response to imposed drought differed from that of uplands; imposed drought did not reduce aboveground tree growth but instead reduced root biomass in mineral soil. At both landscape positions, imposed drought accelerated the loss of understory vegetation. Overall, the results of the throughfall exclusion indicated that chronic soil drying is likely to increase forest C storage only in floodplains. In uplands, where soil moisture is more limited, forest C storage is not as likely to change because an increase in soil C may be offset by reduced tree growth"--Leaf iiiBonanza Creek Long-Term Ecological Research Program (funded jointly by NSF grant DEB-0423442 and USDA Forest Service Pacific Northwest Research Station grant PNW01-JV11261952-231), McIntyre-Stennis Research Program at the School of Natural Resources and Agricultural Sciences, UAF, Center for Global Change, and UAF Graduate School1. General introduction -- 2. Landscape position influences the responses of boreal forest vegetation to long-term experimental drought in Interior Alaska -- 3. Long-term (1989-2005) experimental drought increases surface soil carbon storage in an interior boreal forest -- 4. General conclusion -- 4.1. Forest soil and vegetation response to imposed drought -- 4.2. Whole-forest C balance -- 4.3. Recommendations for future research -- 4.4. References

The Heather Vole, Genus Phenacomys, in Alaska

Four specimens of heather vole (genus Phenacomys) collected in the coastal mountains of Southeast Alaska document the first Recent records of this vole in Alaska. Alternative hypotheses on the relationship of these newly-discovered populations to extant and historical populations are outlined, and additional studies proposed