title: Phylogeography of microbial phototrophs in the dry valleys of the high Himalayas and Antarctica.
abstract: High-elevation valleys in dry areas of the Himalayas are among the most extreme, yet least explored environments on Earth. These barren, rocky valleys are subjected to year-round temperature fluctuations across the freezing point and very low availability of water and nutrients, causing previous workers to hypothesize that no photoautotrophic life (primary producers) exists in these locations. However, there has been no work using modern biogeochemical or culture-independent molecular methods to test the hypothesis that photoautotrophs are absent from high Himalayan soil systems. Here, we show that although microbial biomass levels are as low as those of the Dry Valleys of Antarctica, there are abundant microbial photoautotrophs, displaying unexpected phylogenetic diversity, in barren soils from just below the permanent ice line of the central Himalayas. Furthermore, we discovered that one of the dominant algal clades from the high Himalayas also contains the dominant algae in culture-independent surveys of both soil and ice samples from the Dry Valleys of Antarctica, revealing an unexpected link between these environmentally similar but geographically very distant systems. Phylogenetic and biogeographic analyses demonstrated that although this algal clade is globally distributed to other high-altitude and high-latitude soils, it shows significant genetic isolation by geographical distance patterns, indicating local adaptation and perhaps speciation in each region. Our results are the first to demonstrate the remarkable similarities of microbial life of arid soils of Antarctica and the high Himalayas. Our findings are a starting point for future comparative studies of the dry valleys of the Himalayas and Antarctica that will yield new insights into the cold and dry limits to life on Earth.
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA. steve.schmidt@colorado.edu
authors.forename: S K
authors.initials: SK
authors.lastname: Schmidt
authors.forename: R C
authors.initials: RC
authors.lastname: Lynch
authors.forename: A J
authors.initials: AJ
authors.lastname: King
authors.forename: D
authors.initials: D
authors.lastname: Karki
authors.forename: M S
authors.initials: MS
authors.lastname: Robeson
authors.forename: L
authors.initials: L
authors.lastname: Nagy
authors.forename: M W
authors.initials: MW
authors.lastname: Williams
authors.forename: M S
authors.initials: MS
authors.lastname: Mitter
authors.forename: K R
authors.initials: KR
authors.lastname: Freeman
mesh_terms: D000531:Altitude; D000864:Antarctic Regions; D001419:Bacteria / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D003710:Demography; D007194:India; D008969:Molecular Sequence Data; D010802:Phylogeny; D058974:Phylogeography; D014867:Water
chemical_list: D014867:Water
references.citation: J Phycol. 2008 Dec;44(6):1572-85
references.pmid: 27039870
references.citation: Appl Environ Microbiol. 2006 Oct;72(10):6773-9
references.pmid: 17021230
references.citation: Science. 2009 Sep 18;325(5947):1541-4
references.pmid: 19762643
references.citation: Trends Ecol Evol. 1988 May;3(5):111-4
references.pmid: 21227160
references.citation: Bioinformatics. 2001 Aug;17(8):754-5
references.pmid: 11524383
references.citation: Appl Environ Microbiol. 2007 Jun;73(11):3497-504
references.pmid: 17416689
references.citation: Extremophiles. 2009 Sep;13(5):807-16
references.pmid: 19597697
references.citation: Nature. 2001 Sep 27;413(6854):380-1
references.pmid: 11574875
references.citation: Nat Rev Microbiol. 2010 Feb;8(2):129-38
references.pmid: 20075927
references.citation: Microb Ecol. 2007 Jan;53(1):110-22
references.pmid: 17186150
references.citation: Appl Environ Microbiol. 2001 Apr;67(4):1902-10
references.pmid: 11282648
references.citation: Nucleic Acids Res. 2004 Feb 25;32(4):1363-71
references.pmid: 14985472
references.citation: Annu Rev Microbiol. 2004;58:649-90
references.pmid: 15487951
references.citation: Plant Cell Environ. 2007 Oct;30(10):1240-55
references.pmid: 17727415
references.citation: Nat Rev Microbiol. 2006 Feb;4(2):102-12
references.pmid: 16415926
references.citation: Proc Natl Acad Sci U S A. 2009 Oct 27;106(43):18315-20
references.pmid: 19826082
references.citation: Environ Microbiol. 2009 Mar;11(3):674-86
references.pmid: 19187281
references.citation: Syst Biol. 2005 Dec;54(6):936-47
references.pmid: 16338765
references.citation: Appl Environ Microbiol. 2009 Feb;75(3):735-47
references.pmid: 19074608
references.citation: Proc Biol Sci. 2009 Oct 22;276(1673):3591-9
references.pmid: 19625320
references.citation: Mol Biol Evol. 2007 Aug;24(8):1596-9
references.pmid: 17488738
references.citation: Extremophiles. 2003 Jun;7(3):177-83
references.pmid: 12768448
references.citation: Mol Cell Proteomics. 2006 Aug;5(8):1520-32
references.pmid: 16769708
references.citation: Nat Commun. 2010 Aug 10;1:53
references.pmid: 20975720
references.citation: Microb Ecol. 2005 Oct;50(3):396-407
references.pmid: 16328651
references.citation: Science. 2008 May 23;320(5879):1039-43
references.pmid: 18497288
references.citation: Proc Biol Sci. 2008 Dec 22;275(1653):2793-802
references.pmid: 18755677