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You searched for +publisher:"Harvard University" +contributor:("Knoll, Andrew H."). Showing records 1 – 3 of 3 total matches.

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Harvard University

1. Olins, Heather Craig. Abiotic Influences on Free-Living Microbial Communities in Hydrothermal Vent Ecosystems.

Degree: PhD, 2016, Harvard University

Hydrothermal vent ecosystems are defined by steep thermal and chemical gradients. Chemosynthetic microorganisms are the primary producers in these systems, utilizing the available chemical energy to support substantial animal biomass. The variety of chemical substrates provided by hydrothermal fluid and surrounding seawater enables a metabolically diverse community of microbes. However, our understanding of how abiotic factors such as temperature, geochemistry, and mineral substrate influence the activity of these microbes is limited. The overarching goal of this dissertation is to examine the influence of these abiotic factors on free-living microbial community composition, structure, and function. In this work I first examined the influence of temperature on primary productivity by using radio isotopic tracer studies to measure rates of carbon fixation by epi- and endolithic microbial communities from vent chimney sulfides. I show evidence that these communities fix more carbon at low temperatures, underscoring the importance of low temperature habitats in these environments commonly characterized by high temperature. I then utilized in situ RNA preservation to examine community-wide microbial activity in low temperature vent fluids throughout a vent field. These data show two distinct activity profiles that cross-cut canonical habitat descriptions, and highlight the importance of the intra-field waters among the discrete vents as regions of high primary productivity bearing similarity in microbial activity to plumes emanating from high temperature chimneys. Finally, I designed novel colonization devices to examine the influence of mineral substrate on microbial community composition, structure, and succession. Mineralogy influenced certain taxa. I also identified potential early and late successional taxa. The combination of metabolic rate measurements, metatranscriptomics, and colonization experiments presented here, all with co-registered geochemistry, underscore the substantial heterogeneity of these systems and offer insights into the relative strengths of the abiotic forces that help to govern these ecosystems.

Biology, Organismic and Evolutionary

Advisors/Committee Members: Girguis, Peter R. xmlui.authority.confidence.description.cf_uncertain (advisor), Knoll, Andrew H. (committee member), Cavanaugh, Colleen (committee member).

Subjects/Keywords: Biology, Microbiology; Biology, Ecology; Biology, Oceanography

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APA (6th Edition):

Olins, H. C. (2016). Abiotic Influences on Free-Living Microbial Communities in Hydrothermal Vent Ecosystems. (Doctoral Dissertation). Harvard University. Retrieved from http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493269

Chicago Manual of Style (16th Edition):

Olins, Heather Craig. “Abiotic Influences on Free-Living Microbial Communities in Hydrothermal Vent Ecosystems.” 2016. Doctoral Dissertation, Harvard University. Accessed January 23, 2020. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493269.

MLA Handbook (7th Edition):

Olins, Heather Craig. “Abiotic Influences on Free-Living Microbial Communities in Hydrothermal Vent Ecosystems.” 2016. Web. 23 Jan 2020.

Vancouver:

Olins HC. Abiotic Influences on Free-Living Microbial Communities in Hydrothermal Vent Ecosystems. [Internet] [Doctoral dissertation]. Harvard University; 2016. [cited 2020 Jan 23]. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493269.

Council of Science Editors:

Olins HC. Abiotic Influences on Free-Living Microbial Communities in Hydrothermal Vent Ecosystems. [Doctoral Dissertation]. Harvard University; 2016. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493269

2. Sanders, Jon G. Disentangling the Coevolutionary Histories of Animal Gut Microbiomes.

Degree: PhD, 2015, Harvard University

Animals associate with microbes in complex interactions with profound fitness consequences. These interactions play an enormous role in the evolution of both partners, and recent advances in sequencing technology have allowed for unprecedented insight into the diversity and distribution of these associations. However, our understanding of the processes generating those patterns remains in its infancy. Here, I explore variation in microbiomes across two animal lineages—ants and mammals—to tease apart the role of these process in the evolution of gut microbiota. First, I explore patterns of phylogenetic correlation in gut microbiota of herbivorous Cephalotes ants and hominid apes. By examining the sensitivity of phylogenetic correlation to analytical parameters, I show that these outwardly similar patterns are likely to be the result of very different processes in each host lineage. Next, I examine in more depth the interacting effects of diet and phylogeny on the structure of baleen whale microbiomes. Whales consume a diet that differs dramatically from that of their closest extant relatives, the herbivorous artiodactyls. I use a combination of marker gene and shotgun metagenomic sequencing to show that a phylogentically conserved host trait, the multichambered gut, leads to functional and taxonomic similarities of whale gut microbiomes to those of their herbivorous ancestors via the fermentation of animal polysaccharides in the exoskeletons of their prey. Finally, I return to ants to examine how major shifts in the nature of gut microbial association correspond to host ecology. Using measures of absolute bacterial abundance, rather than diversity, I test the hypothesis that evolution of symbiosis with microbes has facilitated ants’ dominance of tropical rainforest canopies. Surprisingly, I find differences in the abundance of gut bacteria in different ant lineages that span many orders of magnitude, suggesting that evolutionary transitions in the functional role of symbiosis in this animal lineage correspond not only to changes in the diversity of these associations, but to changes in kind. The results of these studies help to clarify the roles of history and selection in structuring animal gut microbiota, hinting that the interaction of these factors may fundamentally differ between animal lineages.

Biology, Organismic and Evolutionary

Advisors/Committee Members: Girguis, Peter R. xmlui.authority.confidence.description.cf_uncertain (advisor), Knoll, Andrew H. (committee member), Alm, Eric (committee member).

Subjects/Keywords: Biology, General; Biology, Microbiology; Biology, Ecology

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Sanders, J. G. (2015). Disentangling the Coevolutionary Histories of Animal Gut Microbiomes. (Doctoral Dissertation). Harvard University. Retrieved from http://nrs.harvard.edu/urn-3:HUL.InstRepos:17463127

Chicago Manual of Style (16th Edition):

Sanders, Jon G. “Disentangling the Coevolutionary Histories of Animal Gut Microbiomes.” 2015. Doctoral Dissertation, Harvard University. Accessed January 23, 2020. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17463127.

MLA Handbook (7th Edition):

Sanders, Jon G. “Disentangling the Coevolutionary Histories of Animal Gut Microbiomes.” 2015. Web. 23 Jan 2020.

Vancouver:

Sanders JG. Disentangling the Coevolutionary Histories of Animal Gut Microbiomes. [Internet] [Doctoral dissertation]. Harvard University; 2015. [cited 2020 Jan 23]. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:17463127.

Council of Science Editors:

Sanders JG. Disentangling the Coevolutionary Histories of Animal Gut Microbiomes. [Doctoral Dissertation]. Harvard University; 2015. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:17463127

3. Strauss, Justin Vincent. The Neoproterozoic and Early Paleozoic Tectonic and Environmental Evolution of Alaska and Northwest Canada.

Degree: PhD, 2015, Harvard University

Neoproterozoic and early Paleozoic sedimentary deposits of the North American Cordillera record large fluctuations in global biogeochemical cycles, the establishment and diversification of multiple eukaryotic clades, the fragmentation of the supercontinent Rodinia, and the protracted development and subsequent demise of the western and northern Laurentian passive margins. Here, I put forth new tectono-, bio-, and chemo-stratigraphic models for the ~780-540 Ma Windermere Supergroup of western North America and “pre-Mississippian” stratigraphy of northern Alaska that refine previous models for the Neoproterozoic and early Paleozoic tectonic and environmental evolution of Alaska and northwest Canada. First, I present an updated model for early Windermere (780–720 Ma) sedimentation in NW Canada through a detailed study of the Callison Lake Formation of the Mount Harper Group, spectacularly exposed in the Coal Creek and Hart River inliers of the Ogilvie Mountains of Yukon, Canada. Twenty-one detailed measured stratigraphic sections are integrated with geological mapping, facies analysis, and new Rhenium-Osmium (Re-Os) geochronology to provide a depositional model for the Callison Lake Formation. Mixed siliciclastic, carbonate, and evaporite sediments record a complex subsidence history in which episodic basinal restriction and abrupt facies change can be tied accumulation in marginal marine embayments formed in discrete hangingwall depocenters of a major Windermere extensional fault zone. New organic-rich rock Re-Os ages of 752.7 ± 5.5 and 739.9 ± 6.1 Ma bracket Callison Lake sedimentation and constrain early Windermere sedimentation in NW Canada to post-date the eruption of the Gunbarrel Large Igneous Province by ~30 million years and predate the successful rift-drift transition by ~200 million years. In order to accommodate coeval extensional and compressional tectonism, abrupt facies change, and Neoproterozoic fault geometries, I propose that NW Canada experienced strike-slip deformation during the ~740–660 Ma early fragmentation of Rodinia. Second, I integrate carbon and oxygen isotope chemostratigraphy, sequence stratigraphy, geochronological data, and microfossil biostratigraphy from the Callison Lake Formation to highlight the potential for margin-wide correlation of Neoproterozoic successions in North America. Here, I also report the discovery of abundant and well-preserved vase-shaped microfossils in the Callison Lake Formation, dated with Re-Os geochronology at 739.9 ± 6.1 Ma, that share multiple species-level taxa with a well-characterized and coeval assemblage from the Chuar Group, Grand Canyon, Arizona dated with U-Pb on zircon from an interbedded tuff at 742 ± 6 Ma. The overlapping age and species assemblages from these two deposits suggests biostratigraphic utility, at least within Neoproterozoic basins of Laurentia, and perhaps globally. Sequence stratigraphic data from the Callison Lake Formation and other basal Windermere successions in northwest Canada delineate four major depositional sequences that… Advisors/Committee Members: Johnston, David T. xmlui.authority.confidence.description.cf_ambiguous (advisor), Knoll, Andrew H. (committee member), Schrag, Daniel P. (committee member).

Subjects/Keywords: Geology

…Sciences at Harvard University, including Sarah Colgan, Cindy Marsh, Maryorie Grande, and… …the Department of Earth and Planetary Sciences at Harvard University, the Graduate Research… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Strauss, J. V. (2015). The Neoproterozoic and Early Paleozoic Tectonic and Environmental Evolution of Alaska and Northwest Canada. (Doctoral Dissertation). Harvard University. Retrieved from http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467317

Chicago Manual of Style (16th Edition):

Strauss, Justin Vincent. “The Neoproterozoic and Early Paleozoic Tectonic and Environmental Evolution of Alaska and Northwest Canada.” 2015. Doctoral Dissertation, Harvard University. Accessed January 23, 2020. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467317.

MLA Handbook (7th Edition):

Strauss, Justin Vincent. “The Neoproterozoic and Early Paleozoic Tectonic and Environmental Evolution of Alaska and Northwest Canada.” 2015. Web. 23 Jan 2020.

Vancouver:

Strauss JV. The Neoproterozoic and Early Paleozoic Tectonic and Environmental Evolution of Alaska and Northwest Canada. [Internet] [Doctoral dissertation]. Harvard University; 2015. [cited 2020 Jan 23]. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467317.

Council of Science Editors:

Strauss JV. The Neoproterozoic and Early Paleozoic Tectonic and Environmental Evolution of Alaska and Northwest Canada. [Doctoral Dissertation]. Harvard University; 2015. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467317

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