Search

Simple Summary: In this study, we implemented a multifaceted approach, coupling phylogenetic, phylogeographical and demographic analyses together with a morphological characterization to depict the genetic patterns of Heleobia atacamensis, an endangered species scattered in isolated and semi-isolated but dynamic habitats of the Atacama Saltpan. We focused on snails obtained from Peine and Tilomonte, two peripherical localities, which were compared with topotypes specimens. The range extension of the species also allowed us to reassess its conservation status. Molecular analyses showed that snails from Peine and Tilomonte belong to Heleobia atacamensis. We also discovered genetic structure in the saltpan, represented by six genetic clusters, besides morphological differences between populations. Since the observed pattern is common for other freshwater species restricted to desert aquifers worldwide, our results represent findings applicable to analogous systems. The species, listed as Critically Endangered at regional level in 2014, was reassessed as Endangered. For an eventual management plan, we suggest incorporating the genetic information obtained here. Evaporitic ecosystems of the Atacama Desert contain a rich endemic fauna, including mollusk species. A recent study performed in the freshwater snail Heleobia atacamensis, endemic to the Atacama Saltpan, revealed a strong interdependence of genetic patterns with climatic fluctuations and landscape physiography. The species is currently listed as Critically Endangered at regional scale and as Data Deficient on the International Union for Conservation of Nature (IUCN) Red List. Here, we studied genetic diversity and demographic history of several populations of the species occurring on a connectivity gradient, including snails from new peripherical localities (Peine and Tilomonte), which were compared with topotype specimens. In addition, we reassessed the conservation status using the IUCN Red List categories and criteria considering species-specific idiosyncrasy. Phylogenetic and phylogeographical analyses indicated that snails from Peine and Tilomonte belong to H. atacamensis. We discovered significant differentiation in shell morphology, which was generally greater in geographically isolated populations. We also inferred six genetic clusters and a demographic expansion congruent with the wet periods that occurred at the end of the Pleistocene. Considering the highest risk category obtained, H. atacamensis was reassessed as Endangered at regional scale. Future conservation plans should consider the genetic assemblages as conservation units. [ABSTRACT FROM AUTHOR]

Understanding how human societies interacted with environmental changes is a major goal of archaeology and other socio-natural sciences. In this paper, we assess the human-environment interactions in the Pampa del Tamarugal (PDT) basin of the Atacama Desert over the last 13,000 years. By relying on a socio-environmental model that integrates ecosystem services with adaptive strategies, we review past climate changes, shifting environmental conditions, and the continuities and discontinuities in the nature and intensity of the human occupation of the PDT. As a result we highlight the importance of certain key resources such as water, an essential factor in the long-term trajectory of eco-historical change. Without water the outcome of human societies becomes hazardous. [ABSTRACT FROM AUTHOR]

BACKGROUND A decrease in rainfall is one of the main constraints on wheat production, although the association of wheat with arbuscular mycorrhizal fungi (AMF) may be an alternative for crop production under drought conditions. In the present study, we used three wheat cultivars (Purple, Ilustre and Maxi Baer) inoculated with two AMF strains, one obtained from the hyperarid Atacama Desert (northern Chile; Fm) and the other obtained from southern Chile (Cc). Plants were maintained under two irrigation conditions (normal irrigation and drought) and the physiological behaviour and enzymatic and nonenzymatic antioxidant activities in the shoots were determined. In addition, the phenolic compounds were identified by high‐performance liquid chromatography‐dioide array detection‐electrospray ionization‐tandem mass spectrometry and quantified. RESULTS: AMF colonization produced higher levels of efficiency of photosystem II and photosynthetic pigments. High values of catalase in Purple‐Cc, ascorbate peroxidase in Purple‐Cc, glutathione reductase in Maxi‐Cc and superoxide dismutase in Purple‐Cc, all under stress, were registered. Of the inoculated cultivars, Purple‐Cc showed the highest flavonoid levels, whereas hydroxycinnamic acids were higher in Maxi‐Fm without drought, with apigenin and luteolin being the most abundant. High levels of phenols were present in the Ilustre‐Fm plants without drought. Under normal irrigation, high levels of antioxidant activity were registered in the AMF treatments, whereas, under stress conditions, in general, high values were observed under the Fm inoculation. CONCLUSION: Our results showed that the greatest antioxidant activity and phenolic content occurred in wheat plants inoculated with AMF, indicating their influence on coping with water stress, which is of importance in vast areas where global climate change is resulting in diminished rainfall. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Abstract: In South America, the arid and semiarid subtropical regions through the Atacama Desert and north-central Chile between 19° and 32°S are currently a gap in the tree-ring chronology network. Only a short tree-ring chronology has been published for this vast region and little is known about the suitability of many woody species for tree-ring analysis and dendroclimatology. In this paper we present the first detailed analysis of the climate responses and influences of the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) on the tree-rings of three species new to dendrochronology and that typically occur at high elevations in the Andes of central and north-central Chile. Three well-replicated tree-ring chronologies of Kageneckia angustifolia, Proustia cuneifolia and Fabiana imbricata are compared with century-long regional records of precipitation and temperature, and with the N3.4 SST and PDO indices in both time and frequency-domains using correlation and wavelet analysis. The radial growth of these species is controlled by winter precipitation and is also positively correlated with temperature during most of the rainy season from April to September (autumn–spring). The regional climate as well as tree growth is strongly modulated by ENSO and ENSO-like conditions in the equatorial Pacific at both interannual and interdecadal timescales. The decadal and interdecadal variability is not correlated with PDO and appears to be related to the Interdecadal Pacific Oscillation (IPO), a Pacific-wide ENSO-like mode of climate variability. Despite their relatively short lifespans, these three new species have a high potential for dendrochronological and dendroclimatic studies in the semiarid region of Chile over the last two centuries. [Copyright &y& Elsevier]

In the Central Atacama Desert (22°-24°S; henceforth CAD), around 3700 cal yrs BP, human economies begin to transition from relying mostly on hunting and gathering to increasingly incorporating horticulture and pastoralism became more intensive during the Late Intermediate Period (LIP; beginning at ca. 1050 cal yrs BP/900 AD). In this extreme environment, the well-being of past and present farming and herding communities is directly tied to water availability. The lack of proper paleoclimatic/environmental records in terms of their temporal/spatial resolution impeded evaluation whether sedentarization was synchronous, in some degree, with the amelioration of dry conditions recorded during the Late Holocene at millennial timescales. The present paper thus aims (1) to reconstruct the past environmental and climatic dynamics in the CAD (22°S) during the late Holocene at millennial to sub-centennial scales based on the pollen record of fossil rodent middens of Cuesta Chita site and; (2) to discuss their possible relationship to changes in cultivation and water management as seen at the archaeological sites of Topaín, Paniri and Turi, located in the Salado River basin. The CCH rodent midden pollen record reflects wetter (drier) than present phases around 4400, 3650, 3000, 2200–2100, 1600, 855–840, 520–450 and 100 cal yrs BP (980, 450-115 cal yrs BP). By the time that wetter-than-present conditions occurred in the CAD (Formative Period, 3500-1050 cal yrs BP), local communities had already developed small-scale horticultural practices, yet they did not develop extensive or intensive agricultural practices. Indeed, historical processes leading to economic transformations and the rapid adoption of intensive agriculture throughout the CAD after 1000 cal yrs BP occurred and were probably favored by wetter than present conditions, suggesting positive correlations between climatic and cultural change. However, these correlations are complex and non-deterministic. In fact, decreased moisture between 650 and 600 cal yrs BP in the Turi Basin was met by agropastoralists at Topaín with complex local strategies that included changing water management practices and significantly extending farmed lands. Similarly, the Topaín fields were abandoned during a period of much-wetter-than-present conditions. The chronologically fine-grained comparison of the CCH and archaeological records reveals that the relationship between climate and culture is complex, non-deterministic, and historically contingent, with examples of agricultural expansion during a time of water stress, and the abandonment of fields during a time of abundance. • Human-environment dynamics in the Central Atacama Desert during the Late Holocene. • Late Holocene climatic variability at millennial to sub-centennial resolution based on pollen records. • Wet (dry) phases occurred ∼4400, 3650, 3000, 2200-2100, 1600, 855-840, 520-450 and 100 (980, 450-115) cal yrs BP. • Human responses to climatic change are various and there is no simple relationship between water availability and land use. [ABSTRACT FROM AUTHOR]

Climate change has become the largest threat to cultural heritage in the twenty-first century. While it is known that the world's most vulnerable populations, including Indigenous peoples, will disproportionately face the effects of climate change, there is less knowledge of the wider cultural frameworks that influence Indigenous understandings of climate change. This article seeks to understand the local perceptions of natural and anthropogenic climate change and its impact on heritage among contemporary indigenous or originario peoples in small oases in the Atacama Desert of Chile's Tarapacá region. Theories from critical heritage studies are used to explore the impacts of both anthropogenic and natural climate change on what is understood as Indigenous heritage. The authors examine how these changes have intersected with national and regional socio-political events in the past century to impact contemporary Indigenous identities in the communities of Pica and Matilla. Semi-structured interviews and oral histories were discontinuously conducted between March 2016 and April 2018 and included lay Aymara and Quechua community members as well as the representatives of local organizations such as Neighbour Councils and Indigenous Development Areas (ADIs) in the communities. These accounts illustrate how recent climate change is being used as a rhetorical device to facilitate the revitalization and regeneration of local ethnicities in northern Chile today. Furthermore, the article demonstrates the value of originario knowledge in understanding the nuances of local cultural context and how essential it is in the implementation of environmental and heritage policies in the wider Chilean context. [ABSTRACT FROM AUTHOR]

Background and Aims Aridity is increasing in many regions of the world, but microclimatic conditions may buffer plant communities from the direct effects of decreased precipitation, creating habitat islands. However, reduced precipitation can also impact these communities indirectly by decreasing the suitability of the surrounding habitat, thus limiting incoming propagules and increasing the chances of population decline and species loss. We test whether decreased precipitation results in loss of species and functional diversity within habitat islands, evaluating in particular whether declines in species diversity and abundance are less likely to result in loss of functional diversity if species/individual loss is stochastic (i.e. independent of species/individual traits) and communities/populations are functionally redundant. Methods Lomas communities are discrete plant communities embedded in the Atacama Desert, maintained by the microclimatic conditions created by fog. We recorded species and functional diversity in six Lomas communities along a 500 km long precipitation gradient in northern Chile. Functional traits were measured in 20 individuals per species, in those species that accounted for approx. 75 % of the abundance at each site. We calculated functional diversity and functional redundancy of the community, and intraspecific functional variation. Key Results Decreased precipitation was associated with lower species diversity and lower species abundances. However, no traits or functional strategies increased or decreased consistently with precipitation, suggesting stochastic species/individual loss. Species with stress-tolerant strategies were predominant in all sites. Although species diversity decreased with decreasing precipitation, functional diversity remained unchanged. Lower functional redundancy in the drier sites suggests that mainly functionally redundant species were lost. Likewise, intraspecific functional variation was similar among communities, despite the lower species abundance in drier sites. Conclusions Decreased precipitation can impact habitat island communities indirectly by decreasing the suitability of the surrounding habitat. Our results support the idea that a stochastic loss of species/individuals from functionally redundant communities and populations does not result in loss of functional diversity. [ABSTRACT FROM AUTHOR]

Intense storms or earthquakes in mountains can supply large amounts of gravel to rivers. Gravel clasts then travel at different rates, with periods of storage and periods of displacement leading to their downstream dispersion over millennia. The rate of this dispersion controls the long-term downcutting rate in mountainous rivers as well as the grain-size signature of climate and tectonic variations in sedimentary basins. Yet, the millennial dispersion rates of gravel are poorly known. Here, we use 10Be concentrations measured in individual pebbles from a localized source along a 56 km-long canyon in the Central Andes to document the distribution of long-term gravel transit rates. We show that an inverse grain-size velocity relationship previously established from short-term tracer gravel in different rivers worldwide can be extrapolated to the long-term transit rates in the Aroma River, suggesting some universality of this relationship. Gravel are also dispersed by large differences in the mean transport rates independent of gravel size, highlighting that some gravel rest at the river surface over tens of thousands of years. These different transport rates imply a strong spreading of the gravel plumes, providing direct proof for the long-term river buffering of sediment signals between mountainous sources and sedimentary basins. The inferred distribution of residence times suggests the first evidence of anomalous diffusion in gravel transport over long timespans. [ABSTRACT FROM AUTHOR]

The Pampa del Tamarugal (PdT; ~19º30'S-21º30'S) is an endorheic basin located today at the core of the Atacama Desert (northern Chile), the most arid desert on earth. Water, a fundamental resource for survival of humans, animals and plants, is a scarce resource in the PdT landscape given that precipitation fall upslope over the Andes and the Altiplano and perennial springs infiltrate in the foothills before reaching this basin. However, discontinue human occupations in the since 13ka and the presence extinct fauna dated 18-14ka southernmost part of the PdT, revealed the presence of water in the past under a highly environmental variability. It is widely known that two pluvial phases occurred in the Atacama Desert (CAPE I-II) and the Altiplano (Tauca and Coipasa phases) during the Late Pleistocene characterized by significant increases of rainfall amount and the consequent environmental changes. However, palaeoecological evidence that allowed to understand the environmental scenarios that supported human populations and extinct fauna in the PdT since and/or during the Late Pleistocene is scarce and fragmentary. Thus, this paper presents new palaeoecological evidences from the PdT in order to shed light to the environmental dynamics and landscape characteristics.Between the Guatacondo and Tambillos ravines, growing evidence shows different features of past landscapes and human activities. Thus, plant macro-remains as leaf litter packs, trunks in horizontal position, in situ bases of trunks, plant stem imprints as well as different sedimentary deposits revealed the presence of paleosprings, paleowetlands and small shallow lacustrine basins during the Late Pleistocene. In Quebrada Maní, for example, large paleowetlands developed until 11ka. Instead, the preserved vegetal macro-remains showed a peculiar spatial pattern of vegetation during that period where Prosopis trunks are more frequent in lowlands (~850 m asl) of PdT while the macro-remains, mainly of Escallonia, are abundant near to the foothill (~1150 masl). Later on, during the early and mid-Holocene, an abrupt decrease in rainfall in the Central Andes generated hiperarid conditions in PdT and consequently, no evidence of human populations was found. Sedimentological observations and OSL dates suggest the development of arid landscapes in the Guatacondo ravine (21ºS) by this time, dating the incision of the ravine sometime between 6.6-1.3ka.After that, a new humid pulse during the Late Holocene (2.5-1ka), associated with new human occupations in PdT characterized by the development of villages and wide field-crops occurred. This period of intensive cultural development and "re-use" of the PdT ended around 1-0.7ka, following a trend to aridization recorded in the rodent middens pollen record. After that the villages of PdT were abandoned and population moved to villages located at higher altitude or associated with water oases active until the present. Around 100-150 yr BP, a brief humid pulse in the PdT occurred synchronously with the reoccupation of the field-crops but probably just seasonally.Acknowledgments: FONDECYT# 1181829; CONICYT/PIA ANILLO SOC1405. [ABSTRACT FROM AUTHOR]

ABSTRACT The Chajnantor plateau is located in the Atacama Desert at over 4800 m above sea level. The plateau features a large fraction of days during the year where dry and stable atmospheric conditions predominate. The suitability of the type of astronomy observations routinely made at sites across the Chajnantor region at different times of the year depends on the variability of atmospheric water vapour. In this work, we study seasonal and intraseasonal variability associated with periods of large and low precipitable water vapour ( PWV) in the Chajnantor region over 32 years. We establish large-scale conditions favourable for above- and below-normal PWV for each of the four seasons. We also explore whether intraseasonal PWV variations are related to the Madden-Julian Oscillation ( MJO). Below-normal PWV in winter, spring, and autumn seasons was found associated with mostly zonal 500- hPa winds, which advect drier than normal air from the anticyclone over the eastern portions of the southeast (SE) Pacific Ocean. In summer, periods with below-normal PWV were found to have anomalously south-westerly winds at mid-levels, also indicating transport of anomalously dry air from the stable SE Pacific. In winter, spring, and autumn seasons, above-normal PWV was generally associated with north-westerly mid-tropospheric wind anomalies, indicating advection of above-normal PWV from the subtropical and tropical regions of the SE Pacific Ocean. Above-normal PWV conditions in summer were associated with nearly calm winds at 500 hPa. Months and phases of the MJO for the most extreme anomalies of PWV for each season agreed well with the seasonal anomalies. Furthermore, three independent reanalysis data sets generally agreed on MJO phases associated with largest positive and negative PWV anomalies. This agreement provides evidence for the first time that the MJO modulates the PWV content over the Atacama Desert. [ABSTRACT FROM AUTHOR]

ABSTRACT In the Lluta Valley, northern Chile, climate is hyperarid and vegetation is restricted to the valley floors and lowermost footslopes. Fossil tree trunks and leaves of predominantly Escallonia angustifolia, however, are abundant up to ∼15 m above the present valley floor, where they are intercalated with slope deposits, reflecting higher water levels in the past. A total of 17 samples have been radiocarbon dated, yielding ages between 38 and 15k cal a BP. The youngest ages of 15.4k cal a BP are interpreted as reflecting the beginning of river incision and lowering of the valley floor, impeding the further growth of trees at higher parts of the slopes. The most plausible scenario for this observation is intensified river incision after 15.4k cal a BP due to increased stream power and runoff from the Río Lluta headwaters in the Western Cordillera and Altiplano corresponding to the highstand of the Tauca and Central Andean Pluvial Event (CAPE) wet phase. [ABSTRACT FROM AUTHOR]

The emergence of complex cultural practices in simple hunter-gatherer groups poses interesting questions on what drives social complexity and what causes the emergence and disappearance of cultural innovations. Here we analyze the conditions that underlie the emergence of artificial mummification in the Chinchorro culture in the coastal Atacama Desert in northern Chile and southern Peru. We provide empirical and theoretical evidence that artificial mummification appeared during a period of increased coastal freshwater availability and marine productivity, which caused an increase in human population size and accelerated the emergence of cultural innovations, as predicted by recent models of cultural and technological evolution. Under a scenario of increasing population size and extreme aridity (with little or no decomposition of corpses) a simple demographic model shows that dead individuals may have become a significant part of the landscape, creating the conditions for the manipulation of the dead that led to the emergence of complex mortuary practices. [ABSTRACT FROM AUTHOR]