title: Functional ecology of an Antarctic Dry Valley.
abstract: The McMurdo Dry Valleys are the largest ice-free region in Antarctica and are critically at risk from climate change. The terrestrial landscape is dominated by oligotrophic mineral soils and extensive exposed rocky surfaces where biota are largely restricted to microbial communities, although their ability to perform the majority of geobiological processes has remained largely uncharacterized. Here, we identified functional traits that drive microbial survival and community assembly, using a metagenomic approach with GeoChip-based functional gene arrays to establish metabolic capabilities in communities inhabiting soil and rock surface niches in McKelvey Valley. Major pathways in primary metabolism were identified, indicating significant plasticity in autotrophic, heterotrophic, and diazotrophic strategies supporting microbial communities. This represents a major advance beyond biodiversity surveys in that we have now identified how putative functional ecology drives microbial community assembly. Significant differences were apparent between open soil, hypolithic, chasmoendolithic, and cryptoendolithic communities. A suite of previously unappreciated Antarctic microbial stress response pathways, thermal, osmotic, and nutrient limitation responses were identified and related to environmental stressors, offering tangible clues to the mechanisms behind the enduring success of microorganisms in this seemingly inhospitable terrain. Rocky substrates exposed to larger fluctuations in environmental stress supported greater functional diversity in stress-response pathways than soils. Soils comprised a unique reservoir of genes involved in transformation of organic hydrocarbons and lignin-like degradative pathways. This has major implications for the evolutionary origin of the organisms, turnover of recalcitrant substrates in Antarctic soils, and predicting future responses to anthropogenic pollution.
authors.affiliation: Institute for Applied Ecology New Zealand, School of Applied Sciences, Auckland University of Technology, Auckland 1142, New Zealand.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Chan
authors.forename: Joy D
authors.initials: JD
authors.lastname: Van Nostrand
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Pointing
authors.forename: Roberta L
authors.initials: RL
authors.lastname: Farrell
mesh_terms: D000704:Analysis of Variance; D000864:Antarctic Regions; D001483:Base Sequence; D005075:Biological Evolution; D002244:Carbon / Q000378:metabolism; D015342:DNA Probes; D004463:Ecology; D017753:Ecosystem; D014644:Genetic Variation; D005843:Geography; D056186:Metagenomics / Q000379:methods; D046228:Microarray Analysis; D008969:Molecular Sequence Data; D012150:Polymorphism, Restriction Fragment Length; D012335:RNA, Ribosomal / Q000235:genetics; D017422:Sequence Analysis, DNA; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology; D013312:Stress, Physiological / Q000235:genetics
chemical_list: D015342:DNA Probes; D012335:RNA, Ribosomal; D012987:Soil; D002244:Carbon