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In the world's highest mountain ranges, uncertainty about the upper elevational range limits of alpine animals represents a critical knowledge gap regarding the environmental limits of life and presents a problem for detecting range shifts in response to climate change. Here we report results of mountaineering mammal surveys in the Central Andes, which led to the discovery of multiple species of mice living at extreme elevations that far surpass previously assumed range limits for mammals. We livetrapped small mammals from ecologically diverse sites spanning >6,700 m of vertical relief, from the desert coast of northern Chile to the summits of the highest volcanoes in the Andes. We used molecular sequence data and whole-genome sequence data to confirm the identities of species that represent new elevational records and to test hypotheses regarding species limits. These discoveries contribute to a new appreciation of the environmental limits of vertebrate life. [ABSTRACT FROM AUTHOR]

The northern region of Chile boasts unique geographical features that support the emergence of geothermal effluents, salt lagoons, and coastal creeks. These extreme climate conditions create polyextreme habitats for microorganisms, particularly adapted to survive these harsh environments. These extremophilic microorganisms hold immense potential as a source of hydrolytic enzymes, among other biotechnological applications. In this study, we isolated 15 strains of aerobic thermophilic bacteria (45–70 °C) from sediment samples collected at five different ecological sites, including hot springs, geothermal fields, and lagoons in the Atacama Desert and Andes high planes. Analyses of the 16S rRNA gene sequences of the isolates showed a close genetic similarity (98–100%) with microorganisms of the genera Parageobacillus, Geobacillus, Anoxybacillus, and Aeribacillus. Notably, these thermophiles exhibited significant hydrolytic enzyme activity, particularly amylases, lipases, and proteases. These findings underscore the potential of using these thermophilic bacterial strains as an invaluable source of thermozymes with wide-ranging applications in diverse industries, such as detergent formulations, pharmaceutical processing, and food technology. This research highlights the ecological significance of these extreme environments in the Atacama Desert and Andes high plains, which serve as vital ecological niches housing extremophilic bacteria as a genetic source of relevant thermozymes, promising great potential for innovation in the biotechnology industry. [ABSTRACT FROM AUTHOR]

Salar de Ascotán is a high-altitude arsenic-rich salt flat exposed to high ultraviolet radiation in the Atacama Desert, Chile. It hosts unique endemic flora and fauna and is an essential habitat for migratory birds, making it an important site for conservation and protection. However, there is limited information on the resident microbiota's diversity, genomic features, metabolic potential, and molecular mechanisms that enable it to thrive in this extreme environment. We used long- and short-read metagenomics to investigate the microbial communities in Ascotán's water, sediment, and soil. Bacteria predominated, mainly Pseudomonadota, Acidobacteriota, and Bacteroidota, with a remarkable diversity of archaea in the soil. Following hybrid assembly, we recovered high-quality bacterial (101) and archaeal (6) metagenome-assembled genomes (MAGs), including representatives of two putative novel families of Patescibacteria and Pseudomonadota and two novel orders from the archaeal classes Halobacteriota and Thermoplasmata. We found different metabolic capabilities across distinct lineages and a widespread presence of genes related to stress response, DNA repair, and resistance to arsenic and other metals. These results highlight the remarkable diversity and taxonomic novelty of the Salar de Ascotán microbiota and its rich functional repertoire, making it able to resist different harsh conditions. The highly complete MAGs described here could serve future studies and bioprospection efforts focused on salt flat extremophiles, and contribute to enriching databases with microbial genome data from underrepresented regions of our planet. [ABSTRACT FROM AUTHOR]

In this study, we examine the long-term trajectory of violence in societies that inhabited the coast of the Atacama Desert in northern Chile using three lines of evidence: bioarchaeology, geoarchaeology and socio-cultural contexts (rock art, weapons, and settlement patterns). These millennia-old populations adopted a way of life, which they maintained for 10,000 years, based on fishing, hunting, and maritime gathering, complementing this with terrestrial resources. We analyzed 288 adult individuals to search for traumas resulting from interpersonal violence and used strontium isotopes 87Sr/86Sr as a proxy to evaluate whether individuals that showed traces of violence were members of local or non-local groups. Moreover, we evaluated settlement patterns, rock art, and weapons. The results show that the violence was invariant during the 10,000 years in which these groups lived without contact with the western world. During the Formative Period (1000 BC-AD 500), however, the type of violence changed, with a substantial increase in lethality. Finally, during the Late Intermediate Period (AD 1000–1450), violence and lethality remained similar to that of the Formative Period. The chemical signal of Sr shows a low frequency of individuals who were coastal outsiders, suggesting that violence occurred between local groups. Moreover, the presence of weapons and rock art depicting scenes of combat supports the notion that these groups engaged in violence. By contrast, the settlement pattern shows no defensive features. We consider that the absence of centralized political systems could have been a causal factor in explaining violence, together with the fact that these populations were organized in small-scale grouping. Another factor may have been competition for the same resources in the extreme environments of the Atacama Desert. Finally, from the Formative Period onward, we cannot rule out a certain level of conflict between fishers and their close neighbors, the horticulturalists. [ABSTRACT FROM AUTHOR]

Our understanding of the limits of animal life is continually revised by scientific exploration of extreme environments. Here we report the discovery of mummified cadavers of leaf-eared mice, Phyllotis vaccarum , from the summits of three different Andean volcanoes at elevations 6,029–6,233 m above sea level in the Puna de Atacama in Chile and Argentina. Such extreme elevations were previously assumed to be completely uninhabitable by mammals. In combination with a live-captured specimen of the same species from the nearby summit of Volcán Llullaillaco (6,739 m) 1 , the summit mummies represent the highest altitude physical records of mammals in the world. We also report a chromosome-level genome assembly for P. vaccarum that, in combination with a whole-genome re-sequencing analysis and radiocarbon dating analysis, provides insights into the provenance and antiquity of the summit mice. Radiocarbon data indicate that the most ancient of the mummies are, at most, a few centuries old. Genomic polymorphism data revealed a high degree of continuity between the summit mice and conspecifics from lower elevations in the surrounding Altiplano. Genomic data also revealed equal numbers of males and females among the summit mice and evidence of close kinship between some individuals from the same summits. These findings bolster evidence for resident populations of Phyllotis at elevations >6,000 m and challenge assumptions about the environmental limits of vertebrate life and the physiological tolerances of small mammals. Storz et al. report the discovery of desiccated cadavers ('mummies') of Andean leaf-eared mice on the summits of several >6000 m Atacama volcanoes, elevations that were assumed to be uninhabitable by mammals. Genomic and radiocarbon data shed light on the origin of the mummies and provide a new understanding of the limits of vertebrate life. [ABSTRACT FROM AUTHOR]

This article presents the results of the interdisciplinary investigation in Quebrada Pedernales (26°S-69°W, Chile 3456 masl), in the highlands of northern Chile. The excavations and surveys carried out revealed a great diversity of pre-Hispanic evidence in an area of the Andes that has been little investigated. This evidence allowed us to reconstruct a sequence of continuous occupation between 11,201–11,612 and 539–634 cal. BP. Zooarchaeological, radiocarbon, technological, geochemical, and carpological analyses suggest wide mobility circuits between the coast and the puna on both slopes of the Andes at the start of the Holocene, coinciding with improved environmental conditions in this area and greater aridity on the coast. A severe lack of human occupation is observed during the mid-Holocene, a phenomenon associated with extreme arid environmental conditions. These trends indicate that the southern limit of influence of this environmental event, which has been recorded in a large part of the south-central Andes, extended into the study area, with a direct impact on the settlement and mobility of human groups. Towards ca. 3000 cal. BP, environmental conditions similar to those of today are associated with the reappearance of archaeological evidence and greater complexity in the formation of settlements, especially in terms of hunting activities. [ABSTRACT FROM AUTHOR]

Introduction: Plants interact with plant growth-promoting bacteria (PGPB), especially under stress condition in natural and agricultural systems. Although a potentially beneficial microbiome has been found associated to plants from alpine systems, this plant- PGPB interaction has been scarcely studied. Nevados de Chillán Complex hold one of the southernmost xerophytic formations in Chile. Plant species living there have to cope with drought and extreme temperatures during the growing season period, microclimatic conditions that become harsher on equatorial than polar slopes, and where the interaction with PGPB could be key for plant survival. Our goal was to study the abundance and activity of different PGPB associated to two abundant plant species of Andean xerophytic formations on contrasting slopes. Methods: Twenty individuals of Berberis empetrifolia and Azorella prolifera shrubs were selected growing on a north and south slope nearby Las Fumarolas, at 2,050 m elevation. On each slope, microclimate based on temperature and moisture conditions were monitored throughout the growing period (oct. -- apr.). Chemical properties of the soil under plant species canopies were also characterized. Bacterial abundance was measured as Log CFU g-1 from soil samples collected from each individual and slope. Then, the most abundant bacterial colonies were selected, and different hormonal (indoleacetic acid) and enzymatic (nitrogenase, phosphatase, ACC- deaminase) mechanisms that promote plant growth were assessed and measured. Results and Discussion: Extreme temperatures were observed in the north facing slope, recording the hottest days (41 vs. 36°C) and coldest nights (-9.9 vs. 6.6°C). Moreover, air and soil moisture were lower on north than on south slope, especially late in the growing season. We found that bacterial abundance was higher in soils on north than on south slope but only under B. empetrifolia canopy. Moreover, the activity of plant growth-promoting mechanisms varied between slopes, being on average higher on north than on south slope, but with plant species-dependent trends. Our work showed how the environmental heterogeneity at microscale in alpine systems (slope and plant species identity) underlies variations in the abundance and plant growth promoting activity of the microorganisms present under the plant canopy of the Andean xerophytic formations and highlight the importance of PGPB from harsh systems as biotechnological tools for restoration. [ABSTRACT FROM AUTHOR]

In extreme environments, microbial organisms reside in pockets with locally habitable conditions. Micro-climates conducive to the persistence of life in an otherwise inhospitable environment—"refugia"—are spatially restricted and can be micro- to centimeters in extent. If martian microbes are preserved in fossil refugia, this presents a double-edged sword for biosignature exploration: these locations will be specific and targetable but small and difficult to find. To better understand what types of features could be refugia in martian salt-encrusted basins, we explore a case study of two terrestrial habitats in salt-encrusted paleo-lake basins (salars): Salar Grande (SG) in the Atacama Desert and Salar de Pajonales (SdP) in the Altiplano Puna plateau of Chile. We review the formation of salt constructs within SG and SdP, which are the features that serve as refugia in those salars, and we explore the connection between the formation of salt constructs at the local scale with the larger-scale geologic phenomena that enable their formation. Our evaluation of terrestrial salars informs an assessment of which chloride basins on Mars might have had a high potential to form life-hosting salt constructs and may preserve biosignatures, or even host extant life. Our survey of martian salars identifies 102 salars in regions with a geographic context conducive to the formation of salt constructs, of which 17 have HiRISE coverage. We investigate these 17 martian salars with HiRISE coverage and locate the presence of possible salt constructs in 16 of them. Salt constructs are features that have may have been continuously habitable for the past ~3.8 Byr, have exceptional preservation potential, and are accessible by robotic exploration. Future work could explore in detail the mechanisms involved in the formation of the topographic features we identified in salt-encrusted basins on Mars to test the hypothesis that they are salt constructs. [ABSTRACT FROM AUTHOR]

The Puquios of the Salar de Llamara in the Atacama Desert, northern Chile, is a system of small lakes that is characterized by evaporitic mineral deposition and that commonly hosts microbial communities. This region is known for its extreme aridity, solar irradiance, and temperature fluctuations. The Puquios are a highly diverse ecosystem with a variety of sedimentary bottom types. Our previous results identified electrical conductivity (EC) as a first-order environmental control on bottom types. In the present paper, we extend our analysis to examine the effects of additional environmental parameters on bottom types and to consider reasons for the importance of EC as a control of sedimentology. Our results identify microbially produced extracellular polymeric substances (EPS) as a major player in the determination of bottom types. The relative amounts and properties of EPS are determined by EC. EPS, in turn, determines the consistency of bottom types, exchange of bottom substrate with the overlying water column, and mineral precipitation within the substrate. Low-EC ponds in the Puquios system have flocculent to semi-cohesive bottom types, with low-viscosity EPS that allows for high-exchange with the surrounding waters and mineral precipitation of granular gypsum, carbonate, and Mg–Si clay in close association with microbes. Ponds with elevated EC have bottom types that are laminated and highly cohesive with high-viscosity EPS that restricts the exchange between sediments and the surrounding waters; mineral precipitation in these high-EC ponds includes granular to laminated gypsum, carbonate and Mg–Si, which also form in close association with microbes. Bottom types in ponds with EC above the threshold for thriving benthic microbial communities have insufficient EPS accumulations to affect mineral precipitation, and the dominant mineral is gypsum (selenite). The variations in EPS production throughout the Puquios, associated with heterogeneity in environmental conditions, make the Puquios region an ideal location for understanding the controls of sedimentary bottom types in evaporative extreme environments that may be similar to those that existed on early Earth and beyond. [ABSTRACT FROM AUTHOR]

We investigated how interacting multi‐scale environmental variables affect taxonomic composition and functional feeding groups of macroinvertebrates in headwater streams of western Patagonia in southern Chile (45–47°S), a region characterised by extreme climatic gradients, intact forested catchments, and recent intense land use change. The opportunity of establishing biological/functional diversity patterns for near‐reference conditions of headwaters streams is paramount.We used multi‐dimensional scaling ordination and boosted regression tree analysis to evaluate the link between reach, catchment, spatial, and regional climatic variables and macroinvertebrate community structure.The high diversity of predators in low productivity streams, together with genera previously unreported for this latitudinal range underscore the unique characteristics and very limited understanding of Patagonian freshwater stream communities.Two main groups of environmental variables were linked to both taxonomic and functional feeding group diversity. The strongly associated variables were related to forest cover (and inversely alpine zone) at the catchment scale, together with stream velocity at the local scale. The second group reflected local indicators of productivity and weathering inputs, associated with the regional east–west precipitation gradient.We present a conceptual model for the catchment scale effects on invertebrate functional groups in forested headwater streams. While the results highlight potentially singular characteristics of the study region, they also suggest a macro‐ecological generalisation of how global change variables, operating on mountain catchments, may differentially affect stream ecosystems as a consequence of the variations in the forest/alpine gradient, across both deciduous and evergreen temperate biomes. [ABSTRACT FROM AUTHOR]

The Salar de Atacama in the Chilean Central Andes harbors unique microbial ecosystems due to extreme environmental conditions, such as high altitude, low oxygen pressure, high solar radiation, and high salinity. Combining X-ray diffraction analyses, scanning electron microscopy and molecular diversity studies, we have characterized twenty previously unexplored Andean microbial ecosystems in eight different lakes and wetlands from the middle-east and south-east regions of this salt flat. The mats and microbialites studied are mainly formed by calcium carbonate (aragonite and calcite) and halite, whereas the endoevaporites are composed predominantly of gypsum and halite. The carbonate-rich mats and microbialites are dominated by Bacteroidetes and Proteobacteria phyla. Within the phylum Proteobacteria , the most abundant classes are Alphaproteobacteria , Gammaproteobacteria and Deltaproteobacteria. While in the phylum Bacteroidetes , the most abundant classes are Bacteroidia and Rhodothermia. Cyanobacteria , Chloroflexi , Planctomycetes , and Verrucomicrobia phyla are also well-represented in the majority of these systems. Gypsum endoevaporites, on the contrary, are dominated by Proteobacteria , Bacteroidetes , and Euryarchaeota phyla. The Cyanobacteria phylum is also abundant in these systems, but it is less represented in comparison to mats and microbialites. Regarding the eukaryotic taxa, diatoms are key structural components in most of the microbial ecosystems studied. The genera of diatoms identified were Achnanthes , Fallacia , Halamphora , Mastogloia , Navicula , Nitzschia , and Surirella. Normally, in the mats and microbialites, diatoms form nano-globular carbonate aggregates with filamentous cyanobacteria and other prokaryotic cells, suggesting their participation in the mineral precipitation process. This work expands our knowledge of the microbial ecosystems inhabiting the extreme environments from the Central Andes region, which is important to ensure their protection and conservation. [ABSTRACT FROM AUTHOR]

Objectives This study aims to assess the health effects on mining workers of exposure to chronic intermittent hypoxia (CIH) at high- and very high-altitude mining compared with similar work at lower altitudes in Chile, and it also aims to constitute the baseline of a 5-year follow-up study. Methods We designed a cross-sectional study to assess health conditions in 483 miners working at 2 levels of altitude exposure: 336 working at a very high or high altitude (HA; 247 above 3900–4400 m, and 89 at 3000–3900 m), and 147 below 2400 m. Subjects were randomly selected in two stages. First, a selection of mines from a census of mines in each altitude stratum was made. Secondly, workers with less than 2 years of employment at each of the selected mines were recruited. The main outcomes measured at the baseline were mountain sickness, sleep alterations, hypertension, body mass index, and neurocognitive functions. Results Prevalence of acute mountain sickness (AMS) was 28.4% in the very high-altitude stratum (P = 0.0001 compared with the low stratum), and 71.7% experienced sleep disturbance (P = 0.02). The adjusted odds ratio for AMS was 9.2 (95% confidence interval: 5.2–16.3) when compared with the very high- and low-altitude groups. Motor processing speed and spatial working memory score were lower for the high-altitude group. Hypertension was lower in the highest-altitude subjects, which may be attributed to preoccupational screening even though this was not statistically significant. Conclusions Despite longer periods of acclimatization to CIH, subjects continue to present AMS and sleep disturbance. Compromise of executive functions was detected, including working memory at HA. Further rigorous research is warranted to understand long-term health impacts of high-altitude mining, and to provide evidence-based policy recommendations. [ABSTRACT FROM AUTHOR]

Summary: Endolithic (rock‐dwelling) microbial communities are ubiquitous in hyper‐arid deserts around the world and the last resort for life under extreme aridity. These communities are excellent models to explore biotic and abiotic drivers of diversity because they are of low complexity. Using high‐throughput amplicon and metagenome sequencing, combined with X‐ray computed tomography, we investigated how water availability and substrate architecture modulated the taxonomic and functional composition of gypsum endolithic communities in the Atacama Desert, Chile. We found that communities inhabiting gypsum rocks with a more fragmented substrate architecture had higher taxonomic and functional diversity, despite having less water available. This effect was tightly linked with community connectedness and likely the result of niche differentiation. Gypsum communities were functionally similar, yet adapted to their unique micro‐habitats by modulating their carbon and energy acquisition strategies and their growth modalities. Reconstructed population genomes showed that these endolithic microbial populations encoded potential pathways for anoxygenic phototrophy and atmospheric hydrogen oxidation as supplemental energy sources. [ABSTRACT FROM AUTHOR]

The El Tatio Geyser Field (ETGF), located in Northern Chile, is the main geyser field in the southern hemisphere. Despite this, details of its microbial ecology are still unknown. Here, we briefly report on the composition and predicted functions of the bacterial community in spouting pool sediments from the ETGF as revealed by high-throughput sequencing of 16S rRNA genes. Results of this analysis showed that while there were differences in richness and diversity between samples, bacterial communities were primarily dominated by the phyla Proteobacteria, followed Firmicutes, Bacteroidetes, Acidobacteria, and Chloroflexi. Analyses of predicted functional activity indicated that the functions were mostly attributed to chemoheterotrophy and aerobic chemoheterotrophy, followed by sulfur (respiration of sulfur compounds and sulfate) and nitrogen (nitrate reduction, respiration of nitrogen and nitrate) cycling. Taken together, our results suggest a high diversity in taxonomy and predictive functions of bacterial communities in sediments from spouting pools. This study provides fundamentally important information on the structure and function predictive functions of microbiota communities in spouting pools. Moreover, since the ETGF is intensively visited and impacted by tens of thousands of tourists every year, our results can be used to help guide the design of sustainable conservation strategies. [ABSTRACT FROM AUTHOR]

Chile is unique because of its diverse extreme environment, ranging from arid climates in the north to polar climates in Patagonia. Microorganisms that live in these environments are called extremophiles, and these habitats experience intense ecosystem changes owing to climate warming. Most studies of extremophiles have focused on their biotechnological potential; however, no study has examined how students describe extremophiles. Therefore, we were interested in answering the following question: How do schoolchildren living in extreme environments describe their environments and extremophiles? We performed an ethnographic study and analyzed the results of 347 representative drawings of participants aged 12-16 years from three schools located in the extreme environments of Chile San Pedro de Atacama (hyper-arid, 2,400 m), Lonquimay (forest, 925 m), and Punta Arenas (sub-Antarctic, 34 m). The social representation approach was used to collect data, and systemic networks were used to organize and systematize the drawings. The study found that, despite differences between extreme environments, certain natural elements, such as trees and the sun, are consistently represented by schoolchildren. The analysis revealed that the urban and rural categories were the two main categories identified. The main systemic networks were rural-sun (21,1%) for hyper-arid areas, urban-tree (14,1%) for forest areas, and urban-furniture (23,4%) for sub-Antarctic areas. When the results were analyzed by sex, we found a statistically significant difference for the rural category in the 7th grade, where girls mentioned being more rural than boys. Students living in hyper-arid areas represented higher extremophile drawings, with 57 extremophiles versus 20 and 39 for students living in sub-Antarctic and forest areas, respectively. Bacteria were extremophiles that were more represented. The results provide evidence that natural variables and semantic features that allow an environment to be categorized as extreme are not represented by children when they are focused on and inspired by the environment in which they live, suggesting that school literacy processes impact representations of their environment because they replicate school textbooks and not necessarily their environment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Rivera, Fontana, Cortes, Merino and Vega.)

The hypersaline lagoons located in evaporation basins or salars (salt flats) in the Atacama Desert are extreme environments harbouring a specialised biota able to survive harsh conditions for life. The knowledge of the parasitic biodiversity of these extreme habitats is still scarce despite their functional importance in regulating relevant non-economic services like habitats of waterbirds. The present study is the first report on the cestode infection of Artemia franciscana Kellogg in Salar de Atacama lagoons in northern Chile. A total of 23 parasite larvae were isolated and identified as belonging to five cestode taxa of the order Cyclophyllidea: two species of the family Hymenolepididae, i.e. Flamingolepis sp. 1 and Flamingolepis sp. 2 (adults parasitic in flamingos); two species of Dilepididae, i.e. Fuhrmannolepis averini (adults parasitic in phalaropes) and Eurycestus avoceti (adult parasitic in charadriforms birds); and one species of Progynotaeniidae, i.e. Gynandrotaenia (?) stammeri (adult parasitic in flamingos). The cysticercoids of each species are described and figured. The study represents the first geographical record of the genera Eurycestus, Gynandrotaenia and Fuhrmannolepis in South America and the first report of Gynandrotaenia and Flamingolepis in A. franciscana in its native range. This survey also contributes to the knowledge of cestodes of Phoenicopteriformes and Charadriiformes and their life cycles in the Neotropical Region. A review of cestodes recorded in brine shrimps of the genus Artemia in the world is provided. Further studies on cestode fauna of aquatic birds and their intermediate hosts in hypersaline habitats of the Neotropical Region are needed to understand their functional role in such extreme and unique ecosystems. [ABSTRACT FROM AUTHOR]

Microorganisms, in the most hyperarid deserts around the world, inhabit the inside of rocks as a survival strategy. Water is essential for life, and the ability of a rock substrate to retain water is essential for its habitability. Here we report the mechanism by which gypsum rocks from the Atacama Desert, Chile, provide water for its colonizing microorganisms. We show that the microorganisms can extract water of crystallization (i.e., structurally ordered) from the rock, inducing a phase transformation from gypsum (CaSO4·2H2O) to an hydrite (CaSO4). To investigate and validate the water extraction and phase transformation mechanisms found in the natural geological environment, we cultivated a cyanobacterium isolate on gypsum rock samples under controlled conditions. We found that the cyanobacteria attached onto high surface energy crystal planes ({011}) of gypsum samples generate a thin biofilm that induced mineral dissolution accompanied by water extraction. This process led to a phase transformation to an anhydrous calcium sulfate, anhydrite, which was formed via reprecipitation and subsequent attachment and alignment of nanocrystals. Results in this work not only shed light on how microorganisms can obtain water under severe xeric conditions butalso provide insights into potential life in even more extreme environments, such as Mars, as well as offering strategies for advanced water storage methods. [ABSTRACT FROM AUTHOR]

This study evaluates hindcast simulations performed with a regional climate model (RCM, RegCM4) driven by reanalysis data (ERA-Interim) over the Pacific coast and Andes Cordillera of extratropical South America. A nested domain configuration at 0. 44 ∘ (∼ 50 km) and 0. 09 ∘ (∼ 10 km) spatial resolutions is used for the simulations. RegCM4 is also driven by a global climate model (GCM, MPI-ESM-MR) on the same domain configuration to asses the added values for temperature and precipitation (historical simulations). Overall, both 10 km hindcast and historical simulation results are promising and exhibit a better representation of near-surface air temperature and precipitation variability compared to the 50 km simulations. High-resolution simulations suppress an overestimation of precipitation over the Andes Cordillera of northern Chile found with the 50 km simulations. The simulated daily temperature and precipitation extreme indices from 10 km hindcast simulation show a closer estimation of the observed fields. A persistent warm bias ( ∼ + 4 ∘ C ) over the Atacama Desert in 10 km hindcast simulation reveals the complexity in representing land surface and radiative processes over the desert. Difficulties in capturing the temperature trend in northern Chile are notable for both hindcast simulations. Both resolutions exhibit added values for temperature and precipitation over large parts of Chile, in particular, the 10 km resolves the coastal-valley Andes transitions over central Chile. Our results highlight that resolutions coarser than 50 km (e.g., GCMs and reanalysis) miss important climate gradients imposed by complex topography. Given that the highest spatial resolution of the current regional simulations over the South America is about 50 km, higher resolutions are important to improve our understanding of the dynamical processes that determine climate over complex terrain and extreme environments. [ABSTRACT FROM AUTHOR]

Chile is topographically and climatically diverse, with a wide array of diverse undisturbed ecosystems that include native plants that are highly adapted to local conditions. However, our understanding of the diversity, activity, and role of rhizobacteria associated with natural vegetation in undisturbed Chilean extreme ecosystems is very poor. In the present study, the combination of denaturing gradient gel electrophoresis and 454-pyrosequencing approaches was used to describe the rhizobacterial community structures of native plants grown in three representative Chilean extreme environments: Atacama Desert (ATA), Andes Mountains (AND), and Antarctic (ANT). Both molecular approaches revealed the presence of Proteobacteria, Bacteroidetes, and Actinobacteria as the dominant phyla in the rhizospheres of native plants. Lower numbers of operational taxonomic units (OTUs) were observed in rhizosphere soils from ATA compared with AND and ANT. Both approaches also showed differences in rhizobacterial community structures between extreme environments and between plant species. The differences among plant species grown in the same environment were attributed to the higher relative abundance of classes Gammaproteobacteria and Alphaproteobacteria. However, further studies are needed to determine which environmental factors regulate the structures of rhizobacterial communities, and how (or if) specific bacterial groups may contribute to the growth and survival of native plants in each Chilean extreme environments. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this work was to investigate the variability of surface organic carbon within the hyper-arid Yungay region of the Atacama Desert. The fraction of Labile Organic Carbon (LOC) in these samples varied from 2 to 73μg per gram of soil with a bi-modal distribution with average content of 17±9μg LOC and 69±3μg LOC for “low” and “high” samples, respectively. Interestingly, there was no relation between organic levels and geomorphologic shapes. While organics are deposited and distributed in these soils via eolic processes, it is suggested that fog is the dynamic mechanism that is responsible for the variability and peaks in organic carbon throughout the area, where a “high” LOC content sample could be indicative of a biological process. It was determined that there was no significant difference between topological feature or geographical position within the hyper-arid samples and LOC. This very curious result has implications for the investigation of run-off gullies on the planet Mars as our work suggests a need for careful consideration of the expectation of increases in concentrations of organic materials associated with following aqueous altered topology. [Copyright &y& Elsevier]

The failure of Viking Lander thermal volatilization (TV) (without or with thermal degradation)-gas chromatography (GC)-MS experiments to detect organics suggests chemical rather than biological interpretations for the reactivity of the martian soil. Here, we report that TV-GC-MS may be blind to low levels of organics on Mars. A comparison between TV-GC-MS and total organics has been conducted for a variety of Mars analog soils. In the Antarctic Dry Valleys and the Atacama and Libyan Deserts we find 10–90 μg of refractory or graphitic carbon per gram of soil, which would have been undetectable by the Viking TV-GC-MS. In iron-containing soils (jarosites from Rio Tinto and Panoche Valley) and the Mars simulant (palogonite), oxidation of the organic material to carbon dioxide (CO2) by iron oxides and/or their salts drastically attenuates the detection of organics. The release of 50–700 ppm of CO2 by TV-GC-MS in the Viking analysis may indicate that an oxidation of organic material took place. Therefore, the martian surface could have several orders of magnitude more organics than the stated Viking detection limit. Because of the simplicity of sample handling, TV-GC-MS is still considered the standard method for organic detection on future Mars missions. We suggest that the design of future organic instruments for Mars should include other methods to be able to detect extinct and/or extant life. [ABSTRACT FROM AUTHOR]

Abstract: The arid Elqui valley, part of the Norte Chico of Chile between 27°S and 33°S latitude, is located south of the hyper-arid Atacama desert. The region is characterized by complex terrain and great different of the surface properties, the latter due to cultivated and irrigated areas along the valley floor and sparse vegetation in the arid surrounding. Here the energy balance of the valley has been investigated to compare the evapo-transpiration of the cultivated area with the one of the natural vegetation and to estimate the dew deposition, which proves to be an important water resource in arid areas. Analyzes are based on two Bowen ratio and two eddy covariance stations, operated in the Elqui valley from 2000 to 2002 and in November 2004, respectively. The Bowen ratio of the natural vegetation is about , but much lower in the cultivated and temporally irrigated area along the valley floor. A typical value of the Bowen ratio of a field covered by potatoes is after harvesting or during dry periods and is to after irrigation events or precipitation. For an area with natural vegetation, the annual accumulated evapo-transpiration reaches 65mmyr−1, which is 65% of the mean annual precipitation and 3.5% of the equivalent net radiation . For the cultivated fields along the valley floor, the annual accumulated evapo-transpiration reaches 750mmyr−1, which is 40% of the equivalent net radiation, , and about 100% of the sum of estimated irrigation and mean annual precipitation (I+P). The annual nocturnal dew deposition is about 5–10mmyr−1 and, thus, serves as an additional water source for natural vegetation, especially during dry years. [Copyright &y& Elsevier]

The prevalence of mites of the genus Demodex and their associations with host age, gender, workplace, and comorbid skin and ocular conditions were studied in participants in Antofagasta, Chile, which is in a region with an extreme environment. We examined 680 participants aged 18-88 yr using standardized surface skin biopsies. Among them, Demodex had a prevalence of 13.5 % (95% confidence interval, 10.88-16.17). A slightly higher prevalence was observed in males (51.1%; 95% confidence interval, 40.9-61.3; nonsignificant) and participants in the 69-88 yr age group (50.0%; 95% confidence interval, 23.8-76.2; P < 0.05). Regarding the species involved, Demodex folliculorum was found in 89.1% (CI 82.7-95.5) of cases, while D. brevis was found in the remaining 10.9% of cases. A higher prevalence (25.0% CI 16.1-33.91) was observed in participants who worked indoors in generally enclosed and dust-rich environments (such as theaters, libraries, and administrative offices). There was also a strong association between Demodex prevalence and conjunctival hyperemia, with 35.9% (95% confidence interval, 9.1-35; OR 17.9) of the Demodex positive participants having this pathology compared to 10.3% of the noninfested participants. In summary, the prevalence of Demodex in Antofagasta, Chile (13.5%) was toward the lower end of the range reported among other regions around the world. Environmental factors such as exposure to the sun (including ultraviolet rays) or environmental pollution may affect the mites. In addition, Demodex genetics (related to virulence) and the ocular or skin microbiota may positively or negatively influence infestation and pathology., (© The Author(s) 2021. Published by Oxford University Press on behalf of Entomological Society of America.All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The hyperarid soils of the Atacama Desert, Chile, contain the largest known nitrate deposits in the world. They also represent one of the most hostile environments for microbial life anywhere in the terrestrial biosphere. Despite known for its extreme dryness, several heavy rainfall events causing localised flash flooding have struck Atacama Desert core regions during the last five years. It remains unclear, however, whether these soils can support microbial denitrification. To answer this, we sampled soils along a hyperaridity gradient in the Atacama Desert and conducted incubation experiments using a robotized continuous flow system under a He/O 2 atmosphere. The impacts of four successive extreme weather events on soil-borne N 2 O and N 2 emissions were investigated, i) water addition, ii) NO 3 − addition, iii) labile carbon (C) addition, and iv) oxygen depletion. The 15N–N 2 O site-preference (SP) approach was further used to examine the source of N 2 O produced. Extremely low N 2 O fluxes were detected shortly after water and NO 3 − addition, whereas pronounced N 2 O and N 2 emissions were recorded after labile-C (glucose) amendment in all soils. Under anoxia, N 2 emissions increased drastically while N 2 O emissions decreased concomitantly, indicating the potential for complete denitrification at all sites. Although increasing aridity significantly reduced soil bacterial richness, microbial potential for denitrification and associated gene abundance (i.e., napA , narG , nirS , nirK , cnorB , qnorB and nosZ) was not affected. The N 2 O15N site preference values based on two end-member model suggested that fungal and bacterial denitrification co-contributed to N 2 O production in less arid sites, whereas bacterial denitrification dominated with increasing aridity. We conclude that soil denitrification functionality is preserved even with lowered microbial richness in the extreme hyperarid Atacama Desert. Future changes in land-use or extreme climate events therefore have a potential to destabilize the immense reserves of nitrate and induce significant N 2 O losses in the region. • Denitrification was shown to occur in the hyperarid Atacama Desert. • Denitrification potential and associated gene abundance was not affected by aridity. • Increasing aridity reduced soil bacterial richness. • Fungal and bacterial denitrification co-contributed to N 2 O production. • Bacterial denitrification dominated N 2 O production with increasing hyperaridity. [ABSTRACT FROM AUTHOR]

A phylogenomic and functional analysis of the first two Crenarchaeota MAGs belonging to El Tatio geysers fields in Chile is reported. A soil sample contiguous to a geothermal activity exposed lagoon of El Tatio was used for shotgun sequencing. Afterwards, contigs were binned into individual population-specific genomes data. A phylogenetic placement was carried out for both MAG 9-5TAT and MAG 47-5TAT. Then functional comparisons and metabolic reconstruction were carried out. Results showed that both MAG 9-5TAT and MAG 47-5TAT likely represent new species in the genus Thermoproteus and the genus Sulfolobus, respectively. These findings provide new insights into the phylogenetic and genomic diversity for archaea species that inhabit the El Tatio geysers field and expand the understanding of the Crenarchaeota phylum diversity. [ABSTRACT FROM AUTHOR]

• Mist cooling is an effective climatic feature in a hot, humid extreme environment characterised by intense solar radiation. • Mist cooling can counter the effect of the urban heat island on outdoor comfort. • Occupant comfort surveys support measured performance testifying the relevance of mist cooling. • Spatial measurements indicate the potential for reaching pedestrian thermal delight and specifically alliesthesia. Within the boundaries of Climate Change, existing hot and humid climates will likely become more extreme, calling for research into solutions that enable the thermal liveability of these environments. There is literature advocating for exploring evaporative cooling in hot and humid climates, having observed that when fine mist is deposited on skin, thermal comfort can be achieved. However, there are only a handful of studies considering the efficacy of misting prototypes in these environments. Thus, an experimental study was conducted to explore the impact of simple mist cooling technologies on outdoor comfort. A full-scale misting prototype was built in the city of Antofagasta, located in the Atacama desert region of Chile, and experiencing high humidity and massive solar radiation. The generated environmental conditions were measured, and thermal comfort questionnaires used to supplement quantitative data interpretation with information on the levels of comfort achieved. The experiment demonstrated the potential of mist cooling in this environment, which led to a significant reduction in air temperature, mean radiant temperature and thus on the universal thermal climate index, without significant increases in ambient humidity. Results showed over a 15 °C cooling effect in all three metrics at peak times, and occupants consistently reported a cooling effect after spending time within the mist. [ABSTRACT FROM AUTHOR]

The isolation of soil bacteria from extreme environments represents a major challenge, but also an opportunity to characterize the metabolic potential of soil bacteria that could promote the growth of plants inhabiting these harsh conditions. The aim of this study was to isolate and identify bacteria from two Chilean desert environments and characterize the beneficial traits for plants through a biochemical approach. By means of different culture strategies, we obtained 39 bacterial soil isolates from the Coppermine Peninsula (Antarctica) and 32 from Lejía Lake shore soil (Atacama Desert). The results obtained from the taxonomic classification and phylogenetic analysis based on 16S rDNA sequences indicated that the isolates belonged to four phyla (Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes), and that the most represented genus at both sites was Pseudomonas. Regarding biochemical characterization, all strains displayed in vitro PGP capabilities, but these were in different proportions that grouped them according to their site of origin. This study contributes with microbial isolates from natural extreme environments with biotechnological potentials in improving plant growth under cold stress. [ABSTRACT FROM AUTHOR]

Salar de Huasco is a wetland in the Andes mountains, located 3800 m above sea level at the Chilean Altiplano. Here we present a study aimed at characterizing the viral fraction and the microbial communities through metagenomic analysis. Two ponds (H0 and H3) were examined in November 2015. Water samples were processed using tangential flow filtration to obtain metagenomes from which the DNA fraction of the sample was amplified and sequenced (HiSeq system, Illumina). The ponds were characterized by freshwater and the viral-like particles to picoplankton ratio was 12.1 and 2.3 for H0 and H3, respectively. A great number of unassigned viral sequences were found in H0 (55.8%) and H3 (32.8%), followed by the family Fuselloviridae 20.8% (H0) and other less relatively abundant groups such as Microviridae (H0, 11.7% and H3, 3.3%) and Inoviridae (H3, 2.7%). The dominant viral sequences in both metagenomes belong to the order Caudovirales, with Siphoviridae being the most important family, especially in H3 (32.7%). The most important bacteria phyla were Proteobacteria, Bacteroidetes and Firmicutes in both sites, followed by Cyanobacteria (H0). Genes encoding lysogenic and lytic enzymes (i.e., recombinases and integrases) were found in H0 and H3, indicating a potential for active viral replication at the time of sampling; this was supported by the presence of viral metabolic auxiliary genes at both sites (e.g., cysteine hydrolase). In total, our study indicates a great novelty of viral groups, differences in taxonomic diversity and replication pathways between sites, which contribute to a better understanding of how viruses balance the cycling of energy and matter in this extreme environment. [ABSTRACT FROM AUTHOR]

Data on historical extreme events provides information not only for water resources planning and management but also for the design of disaster-prevention measures. However, most basins around the globe lack long-term hydro-meteorological information to derive the trend of hydrological extremes. This study aims to investigate a method to estimate maximum and minimum flow trends in basins with limited streamflow records. To carry out this study, data from the Allipén River watershed (Chile), the Hydrologiska Byråns Vattenbalansavdelning (HBV) hydrological model at a daily time step, and an uncertainty analysis were used. Through a calibration using only five years of records, 21-year mean daily flow series were generated and the extreme values derived. To analyze the effect of the length of data availability, 2, 5, and 10 years of flows were eliminated from the analyses. The results show that in the case of 11 years of simulated flows, the annual maximum and minimum flow trends present greater uncertainty than in the cases of 16 and 19 years of simulated flows. Simulating 16 years, however, proved to properly simulate the observed long-term trends. Therefore, in data-scarce areas, the use of a hydrological model to simulate extreme mean daily flows and estimate long-term trends with at least 16 years of meteorological data could be a valid option. [ABSTRACT FROM AUTHOR]

The Atacama Desert in northern Chile is the driest place in the world. Nevertheless, it hasexperienced some rare, extreme rainfall events that have caused landscape changes. Rainevents of March 2015 and July 1991 caused extensive damage in some locations. Attempts atspatially comprehensive detection of areas that change due to rainfall include use of InSARafter the March 2015 rain event in Antofagasta Province, Chile (Scott et al., 2017). In thiswork, we employ a new method to delimit the areas of important change in the physicalcharacteristics of the surface using LANDSAT imagery; one of the cases allowscomparison to the InSAR approach. The process is an easy, semiautomatic, andreproducible methodology that has the potential to identify the types of surfacechange. The method is based on a succession of filters that constrain the area ofchange due to extreme rain, while deleting areas of human activities and of shadowchange.The filter sequence starts with the identification of areas of human activity using two differentinformation sources: a map of historical mine disturbances based on visual inspection ofoptical satellite images, and the extreme differences between two before-rain LANDSATscenes. The latter are identified using the extreme Chi-square values produced using IrMAD(Nielsen and Morton, 2011), an unsupervised change-detection procedure which is also ableto characterize the degree of change. The two products are merged into one Human Activitypolygon (HA). Areas with high degrees of change in shadows are identified using simplehillshades (Shadow Changes polygon, SC). Then, we combine HA and SC to form a non-raineffect area (Non-Rain polygon, NR). Finally, with the NR polygon masked, weextract the high-value IrMAD results from a set of images for dates before andafter a rain event (Second Chi-Square polygon, SCS) to define the area of true raininfluence.Using the area of true change as a mask of the MAD (multivariate alteration determination)rasters, which corresponds to the variance in every spot in different wavelengthof the six bands (1,2,3,4,5,7 for the 1991 rain event and 2,3,4,5,6,7 for the 2015event), we performed an unsupervised classification in ArcGIS software, selecting 10classes.The unsupervised classification shows great potential for delimiting categories of change –erosion, deposition or moisture content - in the playa-lakes and channels. One class correlatestrongly to alluvial fans and colluvium-covered hillslopes. However, it is ambiguous whetherthe hillslope changes result from non-filtered shadow changes or real soil surface changes.Additionally, there are some classes that mainly show cloud change and LANDSATmisdetection areas.Nielsen, A. A, and Morton, C. J., 2011, A Method for Unsupervised Change Detection andAutomatic Radiometric Normalization in Multispectral Data: 34th International Symposiumon Remote Sensing of Environment (Sydney, Australia: ISPRS, 2011).Scott, C., Lohman, R., and Jordan, T.E., 2017, InSAR constraints on soil moisture evolutionafter the March 2015 extreme precipitation event in Chile: Scientific Reports, 7(4903),10.1038/s41598-017-05123-4.2. [ABSTRACT FROM AUTHOR]

Phosphorous (P) is a key element for life on earth. Since microbes take up P largely as orthophosphate, the speciation of P, especially its solubility in soil is more important than its absolute amount. P adsorbed to soil particles shows differing availability depending on particle size distribution, carbon (C) content and structure and amount of poorly crystalline Fe- and Al-oxyhydroxides. We conducted a laboratory incubation study with soils from four study sites on similar granitic parent material along the Coastal Cordillera of Chile, comprising a gradient from arid to humid temperate climate. In a short-term batch experiment, we determined adsorption kinetics by isotopic dilution (33P) for the four different soils in each A and B horizons. Sterile (γ-irradiated) soil was used for adsorption to exclude any biotic uptake and immobilization of inorganic P (Pi), i.e. to solely target the mobilization from adsorbed and precipitated P species. Natural soil was mixed with a proportion of the labelled soil and incubated for 25 days at constant temperature and water content. A subset of the mesocosms was treated with 13C enriched glucose to test for the effect of an easily available C source providing resources for P mobilization. We hypothesized that (I) total microbial P incorporation will be greatest in the most southern ecosystem where microbial activity is highest but (II) microbial driven Pi mobilization will show a unimodal distribution considering the gradient from dry to humid climate regimes as sorption of P is expected to be strongest at the climatic extremes and (III) the response to addition of glucose will be most expressed in soils from the arid regions, which are adapted to efficient utilization of pulse events in C availability.Sorption of P was strongest under arid and humid temperate climate and within these soils highest in the A horizon with up to >90% of the added tracer adsorbed to the soil matrix. Exchangeable Pi was lowest in the A horizon of the Mediterranean and in the humid temperate site with a high C content and high amounts of poorly crystalline Al- and Fe-oxyhydroxides. Uptake of P was strongly enhanced by the addition of glucose, increase in Pi mobilization capacity of microbes was stronger in A than B horizons for all soils. Microbial driven mobilization of Pi was strongest in the semi-arid and Mediterranean site and can partly be attributed to less strongly adsorbed P in these sites. Increase of microbial C by the addition of glucose was strongest in the arid and semi-arid site. This might be explained by a microbial community adapted to rare events in which C suddenly gets available and nutrients rapidly need to get utilized.This study reveals that P uptake is mediated by sorption kinetics more than by total amount of P. Adaptation of microorganisms to environmental conditions plays a major role in their response to an added energy source and determines their ability to mobilize Pi. This contrasting microbial P mobilization dynamics along the climatic gradient has critical feedback on ecosystem P nutrition. [ABSTRACT FROM AUTHOR]

Exoelectrogenic communities for bioelectrochemical systems such as microbial fuel cells (MFCs) are usually enriched from microbial consortia of municipal wastewater treatment plants and other circumneutral and mesophilic environments. Thus, the study of extreme environments offers an enormous potential to find new exoelectrogens and expand the functionality and applications of MFC technology. In this study, a microbial community previously enriched from acid mine drainage (AMD) sediments was used as inoculum in single-chamber MFCs operated at pH 3.7. The power obtained from the AMD-derived inoculum reached 1 mW m -2 (27.1 ± 7.8 mV with 1 kΩ external resistance), which compares to previous MFC studies operated under low-pH conditions. Additionally, polarization curves showed power-generation levels of 2.4 ± 0.2 mW m -2 and 0.4 ± 0.3 mW m -2 , which were associated with the different inoculum sources: MFCs operated with sulfate concentrations of ~2000 and < 25 mg L -1 , respectively. Microbial characterization performed at the end of the operation showed that both anodic and cathodic biofilm communities were highly dominated by the Proteobacteria phylum (>72% of 16S rRNA gene sequences), followed by Firmicutes (4-11%). Furthermore, the anodic microbial communities of the best-performing reactors were dominated by the Delftia genus (phylum Proteobacteria), which was recently identified as a taxon including exoelectrogenic candidates. These findings expand the literature of low-pH operated MFCs and acid-tolerant exoelectrogens, and also represent a starting point to apply this technology to treat acidic organic loads., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Several studies have demonstrated the relevance of endophytic bacteria on the growth and fitness of agriculturally-relevant plants. To our knowledge, however, little information is available on the composition, diversity, and interaction of endophytic bacterial communities in plants struggling for existence in the extreme environments of Chile, such as the Atacama Desert (AD) and Patagonia (PAT). The main objective of the present study was to analyze and compare the composition of endophytic bacterial communities associated with roots and leaves of representative plants growing in Chilean extreme environments. The plants sampled were: Distichlis spicate and Pluchea absinthioides from the AD, and Gaultheria mucronata and Hieracium pilosella from PAT. The abundance and composition of their endophytic bacterial communities was determined by quantitative PCR and high-throughput sequencing of 16S rRNA, respectively. Results indicated that there was a greater abundance of 16S rRNA genes in plants from PAT (10 13 to 10 14 copies g -1 DNA), compared with those from AD (10 10 to 10 12 copies g -1 DNA). In the AD, a greater bacterial diversity, as estimated by Shannon index, was found in P. absinthioides, compared with D. spicata. In both ecosystems, the greater relative abundances of endophytes were mainly attributed to members of the phyla Proteobacteria (14% to 68%), Firmicutes (26% to 41%), Actinobacteria (6 to 23%) and Bacteroidetes (1% to 21%). Our observations revealed that most of operational taxonomic units (OTUs) were not shared between tissue samples of different plant species in both locations, suggesting the effect of the plant genotype (species) on the bacterial endophyte communities in Chilean extreme environments, where Bacillaceae and Enterobacteriacea could serve as keystone taxa as revealed our linear discriminant analysis.

With this study we aim to extend the knowledge on the biogeography of craspedid choanoflagellates with additional data from extreme environments. Up to now, very little is known about choanoflagellates from extreme saline environments, as most studies have focused on marine and freshwater habitats. Though previously investigated high saline ice biota communities have indicated a possible adaptation to environments with high salt concentrations. Hypersaline endorheic basins, so-called salt flats or salares from the Atacama Desert in Northern Chile provide an intense environment regarding fluctuating and extreme salinities, which allow for studies on evolutionary adaptations of protists to hypersaline conditions. This study focused on choanoflagellate species isolated from different salt flats, their morphological characteristics using light and electron microscopy, molecular marker genes (SSU and LSU rDNA) and their salinity tolerance. Here, we described four new craspedid choanoflagellate species, highly adapted to the hypersaline environment of the Atacama Desert. This study extends our knowledge on choanoflagellate phylogeny and ecology and can become the basis for further molecular studies to understand the mechanisms of adaptations. Additionally, we emphasize the need of adding additional data such as autecological characteristics to amend species definitions, which is only possible from cultivated strains. This data would support the use of molecular data originating from metagenomic analyses also in an ecological context., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

The aim of this study was to understand the spatial distribution of microbial communities (18S and 16S rRNA genes) across one of the harshest terrestrial landscapes on Earth. We carried out Illumina sequencing using samples from two expeditions to the high slopes (up to 6050 m.a.s.l.) of Volcán Socompa and Llullaillaco to describe the microbial communities associated with the extremely dry tephra compared to areas that receive water from fumaroles and ice fields made up of nieves penitentes. There were strong spatial patterns relative to these landscape features with the most diverse (alpha diversity) communities being associated with fumaroles. Penitentes did not significantly increase alpha diversity compared to dry tephra at the same elevation (5825 m.a.s.l.) on Volcán Socompa, but the structure of the 18S community (beta diversity) was significantly affected by the presence of penitentes on both Socompa and Llullaillaco. In addition, the 18S community was significantly different in tephra wetted by penitentes versus dry tephra sites across many elevations on Llullaillaco. Traditional phototrophs (algae and cyanobacteria) were abundant in wetter tephra associated with fumaroles, and algae (but not cyanobacteria) were common in tephra associated with penitentes. Dry tephra had neither algae nor cyanobacteria but did host potential phototrophs in the Rhodospirillales on Volcán Llullaillaco, but not on Socompa. These results provide new insights into the distribution of microbes across one of the most extreme terrestrial environments on Earth and provide the first ever glimpse of life associated with nieves penitentes, spire-shaped ice structures that are widespread across the mostly unexplored high-elevation Andean Central Volcanic Zone.

The article provides information on the Atacama Desert in Chile, considered the driest land in the world, where some places have not received a drop of rain in hundreds of years of recorded history. The Atacama lies between the Andes and the Pacific Ocean. One factor in the Atacama's aridity is water, as the Humboldt Current, a frigid river that flows from south to north past the west coast of South America, cools the dry Atacaman air, creating distinct inversion layers.

A correction to the article "Exploring Possible Connections Between Hydrological Extreme Events and Climate Change in Central South Chile" that was published in one of the 2013 issues is presented.