<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>32</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Risteca, Paul J.</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">John E. Barrett</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Influence of landscape-variation in geochemistry on taxonomic and functional composition of microbial mat communities in the McMurdo Dry Valleys, Antarctica</style></title><secondary-title><style face="normal" font="default" size="100%">Biological Sciences</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">carbon</style></keyword><keyword><style  face="normal" font="default" size="100%">microbial community</style></keyword><keyword><style  face="normal" font="default" size="100%">microbial mat</style></keyword><keyword><style  face="normal" font="default" size="100%">nitrogen</style></keyword><keyword><style  face="normal" font="default" size="100%">phosphorus</style></keyword><keyword><style  face="normal" font="default" size="100%">polar desert</style></keyword><keyword><style  face="normal" font="default" size="100%">soil</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2023</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://hdl.handle.net/10919/115384</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">Virginia Tech</style></publisher><pub-location><style face="normal" font="default" size="100%">Blacksburg, VA</style></pub-location><volume><style face="normal" font="default" size="100%">M.S.</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Microbial communities play critical roles in biogeochemical cycles of aquatic and terrestrial ecosystems, but studies of soil microbial communities have been limited by the diversity and complexity found in most ecosystems. Here we report on work investigating the functional diversity of microbial mat and underlying soil communities in the McMurdo Dry Valleys of Antarctica across a gradient of phosphorus availability on glacial tills of distinct age and mineral composition in Taylor Valley, Antarctica. Microbial mat and soil DNA were extracted and sequenced on an Illumina NextSeq500 in a 150 bp paired end format. Raw sequences were uploaded to the MG-RAST server for processing and annotation. Community taxonomic and functional annotation were determined using the RefSeq and SEED Subsystem databases, respectively. The results revealed significant variation in microbial mat community taxonomic composition between the two tills, strongly associated with visual assessment of mat morphology, e.g., &amp;quot;black&amp;quot; and &amp;quot;orange&amp;quot; mats, and soil N:P ratios. The underlying soil microbial communities did not exhibit significant differences in diversity between the two tills, but community composition varied significantly across gradients of soil chemistry, particularly extractable-phosphate content even within tills. The relative abundance of biogeochemistry-relevant pathways determined from the SEED database varied amongst soil microbial communities between the two tills. For example, microbial mat communities exhibited significant variation in the relative abundance of key nitrogen and phosphorus metabolism associated genes strongly associated with the underlying soil N:P. These results suggest that spatial variation in geochemistry influences the distribution and activity of microbial mats, but that the microbial mats themselves also exert a significant homogenizing effect on the underlying soil communities and some of the key biogeochemical processes they facilitate.&lt;/p&gt;</style></abstract><work-type><style face="normal" font="default" size="100%">masters</style></work-type></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>32</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Saurey, Sabrina D.</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">Aanderud, Zachary T.</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Resource Legacies and Priming Regulate Microbial Communities in Antarctica's Dry Valleys</style></title><secondary-title><style face="normal" font="default" size="100%">Department of Plant and Wildlife Sciences</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">454 pyrosequencing</style></keyword><keyword><style  face="normal" font="default" size="100%">Antarctica</style></keyword><keyword><style  face="normal" font="default" size="100%">bacteria</style></keyword><keyword><style  face="normal" font="default" size="100%">microbial ecology</style></keyword><keyword><style  face="normal" font="default" size="100%">soil</style></keyword><keyword><style  face="normal" font="default" size="100%">soil ecology</style></keyword><keyword><style  face="normal" font="default" size="100%">stable isotope probing</style></keyword><keyword><style  face="normal" font="default" size="100%">target metagenomics</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2013</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://hdl.lib.byu.edu/1877/etd6229</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">Brigham Young University</style></publisher><pub-location><style face="normal" font="default" size="100%">Provo, UT</style></pub-location><volume><style face="normal" font="default" size="100%">M.S.</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Multiple mechanisms control bacterial community structure but two in particular, the &amp;quot;legacy&amp;quot; of past environmental conditions, and the &amp;quot;priming&amp;quot; of bacteria to respond to seasonal or reoccurring fluctuations in resources, have the potential to determine both bacterial communities, as well as, temporal shifts in active bacterial taxa. To begin to evaluate the legacy effects of resources on microbial communities, we added four limiting resources annually (i.e., water only; C-mannitol + water; N-NH4NO3 + water; and C, N + water) and measured shifts in bacterial community composition after seven years in a cold desert ecosystem in the McMurdo Dry Valleys, Antarctica. Further, to investigate the ecological significance of priming, we conducted a series of stable isotope probing experiments (i.e., 18O-DNA SIP with 18O-labeled water, 13C-DNA SIP with 13C-labeled mannitol, 15N-DNA with 15N- NH4NO3, and a combined C and N SIP) and characterized the responding (i.e., isotopically labeled) and seed bank (i.e., unlabeled) bacterial communities. We performed each of the SIPs in soil microcosms corresponding to a single resource manipulation (e.g., 13C-labeled mannitol in C addition soils). We hypothesized that all long-term additions of nutrients and water will lead to a distinct bacterial community&amp;mdash;a legacy effect due to the nutrient and water impoverished state of Antarctica soils. We also hypothesized that the stronger the legacy effects demonstrated by a specific community the more adapted or primed bacterial species will be to take advantage of the resource and respond. As hypothesized, resource additions created distinct bacterial legacy but to different degrees among the treatments. The extent of the resource legacy effects was greatest in the CN, intermediate in water and N, and lowest in C communities relative to the control communities, suggesting that C induced changes in communities were intensified by tandem N additions and that water alone created a more distinct legacy than water and C additions combined. Contrary to our hypothesis, the stronger the legacy effects, the less adapted or primed the community was to take advantage of resource additions. For example, the CN treatment that induced the greatest effect on bacterial communities had the lowest number of species (20.9%) in common between the responding and seed bank communities. This inverse relationship may be due to only two species (i.e., Arthrobacter, Actinobacteria and Massilia, Betaproteobacteria) really being primed to take advantage of CN and these species constituting over 75% of the seed bank community. Water, N, and C additions had similar levels of priming with 38.4%, 41.4%, and 36.3% of the responding species being present in the seed bank community, respectively. But of these three treatments, only the priming with water resulted in a unique responding community, suggesting that water, a universal bacterial resource, was enough to prime bacteria. Furthermore, water generates the most diverse responding community of all the resources with stemming from all of the fourteen dominant phyla. We did find patterns of ecological coherence among the responders, especially in the major responders (i.e., responders that increased in relative recovery by at least ten-fold). These responders were predominantly found in only three phyla (i.e., Actinobacteria, Bacteriodetes, and Gammaproteobacteria) regardless of resource addition. Alternatively minor responders (i.e., responders that increased in relative recovery at least two-fold) were contained in fourteen different phyla with specific taxa stimulated by CN (i.e., Betaproteobacteria) and N and water (i.e., Deltaproteobacteria). Further, resource additions elicited responses from 37% of bacterial species with species specializing on a specific resource (e.g., Chloroflexi) or being a generalist (e.g., Planctomycetes and Gammaproteobacteria). Our results offer the first direct links between legacy and priming effects on bacterial community composition and demonstrate that these mechanisms are not always complimentary leading to the formation of similar communities but may both be essential to maintain the high levels of bacterial diversity. Further, all resources produced elicited responders that were either specialists of generalists demonstrating that even bacteria in the extreme environment of Antarctica respond to pulses of resources.&lt;/p&gt;</style></abstract><work-type><style face="normal" font="default" size="100%">masters</style></work-type></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Diana H. Wall</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Global Change tipping points: Above- and below-ground biotic interactions in a low diversity ecosystem</style></title><secondary-title><style face="normal" font="default" size="100%">Philosophical Transactions of the Royal Society B, Biological Sciences</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Biggie</style></keyword><keyword><style  face="normal" font="default" size="100%">soil</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2007</style></year><pub-dates><date><style  face="normal" font="default" size="100%">12/2007</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://rstb.royalsocietypublishing.org/content/362/1488/2291.full</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">362</style></volume><pages><style face="normal" font="default" size="100%">2291-2306</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;&lt;span style=&quot;color: rgb(51, 49, 50); font-family: Arial, Helvetica, sans-serif; font-size: 14px; line-height: 26.04px;&quot;&gt;Low diversity ecosystems are expected to be more vulnerable to global changes although they have received less attention than high diversity ecosystems. Addressing the present state of the Antarctic Dry Valley region by focusing on the potential global changes that may alter the coupling of above- and below-ground species and ecosystem processes is a realistic and critical need that has value beyond the Antarctic community. Presented here are suggested implications of global change on the Dry Valley terrestrial systems and how these effects might be manifested in the future.&lt;/span&gt;&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">1488</style></issue><work-type><style face="normal" font="default" size="100%">Journal</style></work-type></record></records></xml>