Landscape history and contemporary environmental drivers of microbial community structure and function

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dc.contributor.authorAltrichter, Adam E.en
dc.contributor.committeechairBarrett, John E.en
dc.contributor.committeememberWebster, Jackson R.en
dc.contributor.committeememberWynne, Randolph H.en
dc.contributor.committeememberGooseff, Michael N.en
dc.contributor.departmentBiologyen
dc.date.accessioned2014-03-14T20:34:12Zen
dc.date.adate2012-05-21en
dc.date.available2014-03-14T20:34:12Zen
dc.date.issued2010-04-10en
dc.date.rdate2012-05-21en
dc.date.sdate2012-04-24en
dc.description.abstractRecent work in microbial ecology has focused on elucidating controls over biogeographic patterns and connecting microbial community composition to ecosystem function. My objective was to investigate the relative influences of landscape legacies and contemporary environmental factors on the distribution of soil microbial communities and their contribution to ecosystem processes across a glacial till sequence in Taylor Valley, Antarctica. Within each till unit, I sampled from dry areas and areas with visible evidence of recent surface water movement generated by seasonal melting of ephemeral snow packs and hillslope ground ice. Using T-RFLP 16S rRNA gene profiles of microbial communities, I analyzed the contribution of till and environmental factors to community similarity, and assessed the functional potential of the microbial community using extracellular enzyme activity assays. Microbial communities were influenced by geochemical differences among both tills and local environments, but especially organized by variables associated with water availability as the first axis of an NMDS ordination was strongly related to shifts in soil moisture content. CCA revealed that tills explained only 3.4% of the variability in community similarity among sites, while geochemical variables explained 18.5%. Extracellular enzyme activity was correlated with relevant geochemical variables reflecting the influence of nutrient limitation on microbial activity. In addition, enzyme activity was related to changes in community similarity, particularly in wet environments with a partial Mantel correlation of 0.32. These results demonstrate how landscape history and environmental conditions can shape the functional potential of a microbial community mediated through shifts in microbial community composition.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-04242012-143200en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-04242012-143200/en
dc.identifier.urihttp://hdl.handle.net/10919/31883en
dc.publisherVirginia Techen
dc.relation.haspartAltrichter_AE_T_2012.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectextracellular enzyme activityen
dc.subjectMcMurdo Dry Valleysen
dc.subjectmicrobial biogeographyen
dc.subjectT-RFLPen
dc.subjectcommunity similarityen
dc.subjectsoil geochemistryen
dc.titleLandscape history and contemporary environmental drivers of microbial community structure and functionen
dc.typeThesisen
thesis.degree.disciplineBiologyen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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