02314nas a2200265   4500008004100000245012500041210006900166260001200235490000700247520147000254653001501724653001101739653001701750653001801767653001101785653004001796100002201836700001501858700002301873700002201896700002401918700002101942700002101963856006401984       2020                        eng d00aEnergetic and environmental constraints on the community structure of benthic microbial mats in Lake Fryxell, Antarctica0 aEnergetic and environmental constraints on the community structu  c02/20200 v963 a<p>Ecological communities are regulated by the flow of energy through environments. Energy flow is typically limited by access to photosynthetically active radiation (PAR) and oxygen concentration (O<sub>2</sub>). The microbial mats growing on the bottom of Lake Fryxell, Antarctica, have well-defined environmental gradients in PAR and (O<sub>2</sub>). We analyzed the metagenomes of layers from these microbial mats to test the extent to which access to oxygen and light controls community structure. We found variation in the diversity and relative abundances of Archaea, Bacteria and Eukaryotes across three (O<sub>2</sub>) and PAR conditions: high (O<sub>2</sub>) and maximum PAR, variable (O<sub>2</sub>) with lower maximum PAR, and low (O<sub>2</sub>) and maximum PAR. We found distinct communities structured by the optimization of energy use on a millimeter-scale across these conditions. In mat layers where (O<sub>2</sub>) was saturated, PAR structured the community. In contrast, (O<sub>2</sub>) positively correlated with diversity and affected the distribution of dominant populations across the three habitats, suggesting that meter-scale diversity is structured by energy availability. Microbial communities changed across covarying gradients of PAR and (O<sub>2</sub>). The comprehensive metagenomic analysis suggests that the benthic microbial communities in Lake Fryxell are structured by energy flow across both meter- and millimeter-scales.</p>10aAntarctica10aenergy10aLake Fryxell10amicrobial mat10aOxygen10aPhotosynthetically Active Radiation1 aDillon, Megan, L.1 aHawes, Ian1 aJungblut, Anne, D.1 aMackey, Tyler, J.1 aEisen, Jonathan, A.1 aDoran, Peter, T.1 aSumner, Dawn, Y.  uhttps://academic.oup.com/femsec/article/96/2/fiz207/5697196