<?xml version="1.0" encoding="UTF-8"?><xml><records><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%">Eric R. Sokol</style></author><author><style face="normal" font="default" size="100%">John E. Barrett</style></author><author><style face="normal" font="default" size="100%">Tyler J. Kohler</style></author><author><style face="normal" font="default" size="100%">Diane M. McKnight</style></author><author><style face="normal" font="default" size="100%">Salvatore, Mark R.</style></author><author><style face="normal" font="default" size="100%">Lee F. Stanish</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Evaluating alternative metacommunity hypotheses for diatoms in the McMurdo Dry Valleys using simulations and remote sensing data</style></title><secondary-title><style face="normal" font="default" size="100%">Frontiers in Ecology and Evolution</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Antarctica</style></keyword><keyword><style  face="normal" font="default" size="100%">Bacillariophyceae</style></keyword><keyword><style  face="normal" font="default" size="100%">dispersal</style></keyword><keyword><style  face="normal" font="default" size="100%">Nostoc</style></keyword><keyword><style  face="normal" font="default" size="100%">stream ecology</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2020</style></year><pub-dates><date><style  face="normal" font="default" size="100%">09/2020</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://www.frontiersin.org/article/10.3389/fevo.2020.521668/full</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">8</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Diatoms are diverse and widespread freshwater Eukaryotes that make excellent microbial subjects for addressing questions in metacommunity ecology. In the McMurdo Dry Valleys of Antarctica, the simple trophic structure of glacier-fed streams provides an ideal outdoor laboratory where well-described diatom assemblages are found within two cyanobacterial mat types, which occupy different habitats and vary in coverage within and among streams. Specifically, black mats of &lt;em&gt;Nostoc&lt;/em&gt; spp. occur in marginal wetted habitats, and orange mats (&lt;em&gt;Oscillatoria&lt;/em&gt; spp. and &lt;em&gt;Phormidium&lt;/em&gt; spp.) occur in areas of consistent stream flow. Despite their importance as bioindicators for changing environmental conditions, the role of dispersal in structuring dry valley diatom metacommunities remains unclear. Here, we use MCSim, a spatially explicit metacommunity simulation package for R, to test alternative hypotheses about the roles of dispersal and species sorting in maintaining the biodiversity of diatom assemblages residing in black and orange mats. The spatial distribution and patchiness of cyanobacterial mat habitats was characterized by remote imagery of the Lake Fryxell sub-catchment in Taylor Valley. The available species pool for diatom metacommunity simulation scenarios was informed by the Antarctic Freshwater Diatoms Database, maintained by the McMurdo Dry Valleys Long Term Ecological Research program. We used simulation outcomes to test the plausibility of alternative community assembly hypotheses to explain empirically observed patterns of freshwater diatom biodiversity in the long-term record. The most plausible simulation scenarios suggest species sorting by environmental filters, alone, was not sufficient to maintain biodiversity in the Fryxell Basin diatom metacommunity. The most plausible scenarios included either (1) neutral models with different immigration rates for diatoms in orange and black mats or (2) species sorting by a relatively weak environmental filter, such that dispersal dynamics also influenced diatom community assembly, but there was not such a strong disparity&amp;nbsp;in immigration rates between mat types. The results point to the importance of dispersal for understanding current and future biodiversity patterns for diatoms in this ecosystem, and more generally, provide further evidence that metacommunity theory is a useful framework for testing hypotheses about microbial community assembly.&lt;/p&gt;</style></abstract></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%">Tyler J. Kohler</style></author></authors><secondary-authors><author><style face="normal" font="default" size="100%">Diane M. McKnight</style></author></secondary-authors></contributors><titles><title><style face="normal" font="default" size="100%">Physical and chemical controls on the abundance and composition of stream microbial mats from the McMurdo Dry Valleys, Antarctica</style></title><secondary-title><style face="normal" font="default" size="100%">Environmental Studies</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">algae</style></keyword><keyword><style  face="normal" font="default" size="100%">Antarctica</style></keyword><keyword><style  face="normal" font="default" size="100%">biological sciences</style></keyword><keyword><style  face="normal" font="default" size="100%">climate change</style></keyword><keyword><style  face="normal" font="default" size="100%">Disturbance</style></keyword><keyword><style  face="normal" font="default" size="100%">earth sciences</style></keyword><keyword><style  face="normal" font="default" size="100%">McMurdo Dry Valleys</style></keyword><keyword><style  face="normal" font="default" size="100%">microbial mats</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2015</style></year></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://search.proquest.com/docview/1690497718?accountid=14503</style></url></web-urls></urls><publisher><style face="normal" font="default" size="100%">University of Colorado</style></publisher><pub-location><style face="normal" font="default" size="100%">Boulder, CO</style></pub-location><volume><style face="normal" font="default" size="100%">Ph.D.</style></volume><pages><style face="normal" font="default" size="100%">272</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;div title=&quot;Page 4&quot;&gt;&lt;div&gt;&lt;div&gt;&lt;p&gt;The McMurdo Dry Valleys of Antarctica are a cold, dry desert, yet perennial microbial mats are abundant in the ephemeral glacial meltwater streams that flow during austral summers. Three types of mats are present (orange, black, and green), and are primarily comprised of filamentous cyanobacteria,&amp;nbsp;Nostoc, and chlorophytes, respectively. Mat types furthermore occupy distinct habitats within streams, utilizing the benthos, hyporheic zone, and water column, which expose them to different environmental conditions. Due to a lack of lateral inflows, allochthonous organic inputs, and negligible grazing activity, these streams are ideal for the controlled ecological study of microbial mats. Here, I investigated how mats will respond to physical disturbance, alterations in the hydrologic regime, and nutrient liberation from permafrost melt in the future. Specifically, I: 1) quantified and characterized the regrowth of mat biomass, community structure, and elemental stoichiometry after a scouring disturbance, 2) investigated how geomorphology and taxonomic identity influences the response of mat biomass to hydrologic regime in transects monitored over two decades, and 3) evaluated relationships between water chemistry and the elemental and isotopic composition of mat types over longitudinal and valley-wide gradients in Taylor Valley. I found that mats recovered ~20-50% of their biomass over the course of an austral summer following scour. Algal communities were significantly different in composition between disturbed and control treatments, but all samples naturally varied in species and elemental stoichiometry over the study period. When the long- term record of mat biomass was compared with hydrologic variables, stream channel mats (orange and green) had the greatest correlations, while marginal mats (black) showed weaker relationships with flow regime. Relationships also differed as a function of stream geomorphology, indicating the importance of substrata and gradient in conjunction with discharge. Lastly, mats showed unique elemental and isotopic compositions. Green and orange mats within the stream channel most reflected water column nutrient concentrations, while black mats showed significant nitrogen fixation. These results highlight the importance of taxonomic identity and habitat to modeling primary production here and elsewhere, and provide insight to how stream microbial mat communities are formed, maintained, and ultimately persist in an isolated polar desert.&lt;/p&gt;&lt;/div&gt;&lt;/div&gt;&lt;/div&gt;&lt;p&gt;&amp;nbsp;&lt;/p&gt;</style></abstract><work-type><style face="normal" font="default" size="100%">doctoral</style></work-type></record></records></xml>