Claudio Latorre - Academia.edu (original) (raw)

Papers by Claudio Latorre

Current scientific evidence shows that humans colonized South America at least 15,000 years ago, ... more Current scientific evidence shows that humans colonized South America at least 15,000 years ago, but there are still many unknown aspects of this process, including the major and minor migratory routes involved, and the pattern of successive occupation of a diverse continental mosaic of ecosystems. In this context, the role of the Andean highlands (≥3400 meters above sea level) has been neglected, because of the supposedly harsh conditions for humans including hypoxia and cold climate. Nevertheless, the environmental and cultural resources available in the high Andes constitutes an important “megapatch” that should be assessed in terms of human settlement patterns. We review the evidence for late Pleistocene/early Holocene hunter-gatherer occupation of one part of this megapatch, the northern Chilean Dry Puna, in its palaeoecological context. We focus on lithic technology, faunal remains, radiocarbon dates, and other archaeological materials related to different social activities, w...

espanolLos grupos sociales que inicialmente habitaban el nucleo hiperarido del Desierto de Atacam... more espanolLos grupos sociales que inicialmente habitaban el nucleo hiperarido del Desierto de Atacama en el norte de Chile durante el Pleistoceno tardio integraron una amplia gama de bienes e ideas, locales, regionales y supra regionales, para su reproduccion social, como lo sugieren las evidencias arqueologicas materiales recuperadas en varios campamentos al aire libre en Pampa del Tamarugal (PdT). Los recursos locales para mantener su vida diaria, incluian materias primas liticas, fibras de plantas y animales, presas de caza y agua dulce adquiridos en un radio de -30 km (ca. 1-2 dias de viaje). A escala regional, se introdujeron algunos elementos desde la costa del Pacifico (60-80 km hacia el oeste, ca. 3 a 4 dias de viaje), incluidos rodados redondeados alargados, utilizados como percutores en la produccion litica y conchas, especialmente de especies no comestibles de moluscos. Desde los Andes (80-150 km al este, ca. 5-8 dias de viaje), obtuvieron fibra de camelido, obsidiana y una ...

Journal of Vertebrate Paleontology

ABSTRACT South America is well known for its abundance of Quaternary fossiliferous deposits, but ... more ABSTRACT South America is well known for its abundance of Quaternary fossiliferous deposits, but well-preserved fossil remains from well-dated sites are scarce in the Atacama Desert and adjacent arid Andes. Here we report on a partially complete skeleton (46%) of a single young (ca. 3–4 years old) extinct horse discovered in the Salar de Surire, a salt flat located on the Andean altiplano of northern Chile (4,250 m asl). Comparative and osteometric morphological analyses identify the specimen as a South American endemic horse Hippidion saldiasi Roth, 1899. A direct AMS radiocarbon date on bone collagen yielded a calibrated age of 13,170 cal yr BP (2σ range: 13,300–13,060 cal yr BP) indicating that it lived near the end of the last glaciation. The body mass of the individual was calculated at approximately 326.4 kg, close to the upper limit of the larger sizes reported for the genus. Stable isotope evidence shows that the Salar de Surire horse relied on an almost 100% C3 diet that is mostly consistent with Hippidion specimens from other environments that also consumed either mixed C3/C4 or fully C3 diets. This finding is now the southernmost high-elevation record for this species and provides further evidence for the broad geographic and ecological distribution of this genus throughout southern South America.

Science of The Total Environment

Nature Plants

The archaeological record shows that large pre-Inca agricultural systems supported settlements fo... more The archaeological record shows that large pre-Inca agricultural systems supported settlements for centuries around the ravines and oases of northern Chile’s hyperarid Atacama Desert. This raises questions about how such productivity was achieved and sustained, and its social implications. Using isotopic data of well-preserved ancient plant remains from Atacama sites, we show a dramatic increase in crop nitrogen isotope values (15N) from ~AD 1000. Maize was most affected, with 15N values as high as +30‰, with human bone collagen following a similar trend; moreover, their carbon isotope values (13C) indicate a considerable increase in the consumption of maize at the same time. We attribute the shift to extremely high 15N values – the highest in the world for archaeological plants – to the use of seabird guano to fertilise crops. Guano – “white gold” as it came to be called – thus sustained agricultural intensification, supporting a substantial population in an otherwise extreme environment.

Quaternary Science Reviews

Environmental Archaeology

Recovery methods and techniques for archaeological sampling can yield major differences in abunda... more Recovery methods and techniques for archaeological sampling can yield major differences in abundance and anatomo-taxonomical representation of animals, affecting past social and ecological reconstruction. Despite being a common organic material in archaeological sites, faunal remains typically exhibit differential preservation of species and skeletal elements due to pre-and post-depositional processes. This is particularly true for small-sized animals such as certain species of fish, whose often small and fragile fragments are difficult to recover and identify. Here, we present the results of a comparative analysis between two ichthyoarchaeological assemblages from Caleta Vitor 3 in northern Chile (CV3, 18°45 ′ 09 ′′ S), an Early to Middle Holocene (9.2-7.6 ka cal BP) Chinchorro shell midden site. We compare samples obtained and processed, both in the field and the lab, using different recovery techniques. We developed a data standardisation procedure to compare and evaluate skeletal representation, taxa distribution and variations throughout the stratigraphic sequence. Our results show that mesh screen size affects not only the abundance and density of fish but also species representation. Moreover, the identification of small pelagic fish at CV3 sheds further light upon prehistoric fishing strategies and social organisation during the site's early occupation.

Science of The Total Environment

Abstract Mining is a major industry in the Atacama Desert, one of the world's leading regions... more Abstract Mining is a major industry in the Atacama Desert, one of the world's leading regions for copper and other minerals. Intense industrialization of copper mining in the mid-twentieth century has likely led to significant environmental pollution through the deposition of heavy metals in the hyperarid Atacama, but how heavy metal pollution has changed over time in arid regions have rarely been assessed. Here, we analyzed both modern and ancient fecal pellets from paleomiddens collected in the central Atacama for heavy metals and by comparing current heavy metal concentrations with pre-industrial ones, we establish ecological baselines for such pollution. Sixteen paleomiddens spanning the last 1,000 years from multiple localities in the eastern Calama Basin (22°S) show elevated concentrations of Cu and As in modern compared to older middens, and that heavy metal, alkali metals and alkaline earth metals show positive correlations with each other. Heavy metals also tend to be higher in paleomiddens collected along perennial rivers in comparison to those collected from surrounding ranges, irrespective of sample age. Twenty paleomiddens spanning the last c. 16,000 years from a single locality (El Hotel) between the Calama and San Pedro de Atacama basins were used to establish long term variations in plant communities and associated heavy metals since the last glacial termination. Results show that heavy metal concentrations including Cr, Mo and B vary over time and tend to be higher in paleomiddens for which Cactaceae are more abundant whereas those dominated by annuals show less of an effect from trace metals. Our results imply that climate change-driven plant community composition plays a key role in explaining how contamination varies in these desert ecosystems and show that paleomiddens are a unique and unexplored source for understanding how heavy metals vary over time. Given their ubiquity in many of the world’s arid regions, they can be used to establish long-term ecological baselines to compare against human alterations.

Nature Plants, 2021

The archaeological record shows that large pre-Inca agricultural systems supported settlements fo... more The archaeological record shows that large pre-Inca agricultural systems supported settlements for centuries around the ravines and oases of northern Chile’s hyperarid Atacama Desert. This raises questions about how such productivity was achieved and sustained, and its social implications. Using isotopic data of well-preserved ancient plant remains from Atacama sites, we show a dramatic increase in crop nitrogen isotope values (15N) from ~AD 1000. Maize was most affected, with 15N values as high as +30‰, with human bone collagen following a similar trend; moreover, their carbon isotope values (13C) indicate a considerable increase in the consumption of maize at the same time. We attribute the shift to extremely high 15N values – the highest in the world for archaeological plants – to the use of seabird guano to fertilise crops. Guano – “white gold” as it came to be called – thus sustained agricultural intensification, supporting a substantial population in an otherwise extreme e...

PAGES news

A total of 25 students from six different countries were chosen from over 40 applicants to attend... more A total of 25 students from six different countries were chosen from over 40 applicants to attend the International Workshop on Methods in Quaternary Paleoecology. The majority of students were from either Argentina or Chile but other countries such as Colombia, Uruguay, France and Germany were also represented. Students participated in half-day lectures given by eight professors dealing with five major topics: Cathy Whitlock (USA) on charcoal records and analyses; Patricio Moreno (Chile), on high-resolution pollen records; Alan Cooper (Australia) on the extraction and analyses of fossil DNA; Ricardo Villalba (Argentina) on dendrochronology and dendroecology; Christopher Moy (USA) on new methods of radiocarbon and stable isotope analyses; Julio Betancourt (USA), Antonio Maldonado (Chile) and Claudio Latorre (Chile) on methods, analyses and case studies in arid lands paleoecology. The course also involved several laboratory demonstrations involving charcoal analyses, coring equipment, tree rings and rodent middens from the Atacama Desert. Aside from the lectures, students were also given the opportunity of presenting their work as talks and posters, followed by comments on methods and results from the course professors and attendees. These presentations dealt with a variety of topics on South American paleoclimatology, paleoecology, biogeography, and archeology using a diverse array of methods and proxies. Among these were fossil pollen records, rodent middens, diatoms, chironomids, phytoliths, dendrochronology, glacial geology and modern analogue techniques. Research covered a vast geographic area, ranging from the Bogotá wetlands in Colombia to the southern cone of South America, along the Atlantic coast of Uruguay and Argentina, as well as the Bolivian Altiplano and the coastal Atacama Desert along the Pacific coast down to the Patagonian icefields. This lively round of discussions and the high quality presentations stimulated interactions not only between students and professors, but also kindled possible interactions among students from different countries.

Vegetation History and Archaeobotany

Throughout Earth's most extreme environments, such as the Kalahari Desert or the Arctic, ... more Throughout Earth's most extreme environments, such as the Kalahari Desert or the Arctic, hunter-gatherers found ingenious ways to obtain proteins and sugars provided by plants for dietary requirements. In the hyperarid Atacama Desert, wild plant resources are scarce and unevenly distributed due to limited water availability. This study brings together all available archaeobotanical evidence gathered in the Atacama Desert from the Late Pleistocene (ca. 13,000 cal bp) until the Inka epoch (ca. 450 cal bp) to help us comprehend when these populations acquired and managed useful plants from the coastal zone, Intermediate Depression, High Andes, as well as tropical and subtropical ecosystems. Widespread introduction of farming crops, water control techniques and cultivation of diverse plants by 3,000 cal bp ended not only a chronic food shortage, but also led to the establishment of a set of staple foods for the Atacama Desert dwellers, a legacy that remains visible today. By contrasting these trends with major sociocultural changes, together with palaeodemographic and climatic fluctuations, we note that humans adapted to, and transformed this hyperarid landscape and oscillating climate, with plants being a key factor in their success. This long-term process, which we term the "Green Revolution", coincided with an exponential increase in the number of social groups inhabiting the Atacama Desert during the Late Holocene.

Vegetation History and Archaeobotany, 2020

Throughout Earth's most extreme environments, such as the Kalahari Desert or the Arctic, hunt... more Throughout Earth's most extreme environments, such as the Kalahari Desert or the Arctic, hunter-gatherers found ingenious ways to obtain proteins and sugars provided by plants for dietary requirements. In the hyperarid Atacama Desert, wild plant resources are scarce and unevenly distributed due to limited water availability. This study brings together all available archaeobotanical evidence gathered in the Atacama Desert from the Late Pleistocene (ca. 13,000 cal bp) until the Inka epoch (ca. 450 cal bp) to help us comprehend when these populations acquired and managed useful plants from the coastal zone, Intermediate Depression, High Andes, as well as tropical and subtropical ecosystems. Widespread introduction of farming crops, water control techniques and cultivation of diverse plants by 3,000 cal bp ended not only a chronic food shortage, but also led to the establishment of a set of staple foods for the Atacama Desert dwellers, a legacy that remains visible today. By contras...

Scientific Reports

Human activities have profoundly altered the global nutrient cycle through Land Use and Cover Cha... more Human activities have profoundly altered the global nutrient cycle through Land Use and Cover Changes (LUCCs) since the industrial revolution and especially during the Great Acceleration (1950 CE). Yet, the impact of such activities on terrestrial and aquatic ecosystems above their ecological baselines are not well known, especially when considering the response of these systems to the intensity of LUCCs on nutrient cycles. Here, we used a multiproxy approach (sedimentological, geochemical and isotopic analyses, historical records, climate data, and satellite images) to evaluate the role that LUCCs have on Nitrogen (N) cycling in a coastal mediterranean watershed system of central Chile over the last two centuries. Despite long-term anthropogenic use (agriculture, cattle grazing) in the Matanzas watershed– lake system, these LUCC appear to have had little impact on nutrient and organic matter transfer since the Spanish Colonial period. In contrast, the largest changes in N dynamics ...

Quaternary Science Reviews

Abstract Paleoparasitology offers a window into prehistoric parasite faunas, and through studying... more Abstract Paleoparasitology offers a window into prehistoric parasite faunas, and through studying time-series of parasite assemblages it may be possible to observe how parasites responded to past environmental or climate change, or habitat loss (host decline). Here, we use DNA metabarcoding to reconstruct parasite assemblages in twenty-eight ancient rodent middens (or paleomiddens) from the central Atacama Desert in northern Chile. The paleomiddens span the last 50,000 years, and include middens deposited before, during and after the Central Andean Pluvial Event (CAPE; 17.5–8.5 ka BP). The CAPE was a period of increased precipitation and vegetation change, which we also demonstrate was associated with changes in local rodent taxa. Thirteen parasite taxa (including lice, mites, ticks, nematodes and coccidians) were identified from the middens, nine of which were likely derived from rodent hosts and four from alternative (insect or avian) hosts. The former are consistent with parasites known to infect South American rodent hosts. At our conservative level of high taxonomic rank assignment, the parasites appear to have been resilient to the major perturbations in climate and host taxa associated with the CAPE, and finer taxonomic resolution would be required to detect whether any species turnover occurred within the identified parasite groups. Rodent paleomiddens are fast becoming an unrivaled source of genomic data that can be used to reconstruct past ecosystem change on multiple taxonomic, temporal and spatial scales providing new insights into ecological responses to global change.

Frontiers in Earth Science

Quaternary Research

A key concern regarding current and future climate change is the possibility of sustained drought... more A key concern regarding current and future climate change is the possibility of sustained droughts that can have profound impacts on societies. As such, multiple paleoclimatic proxies are needed to identify megadroughts, the synoptic climatology responsible for these droughts, and their impacts on past and future societies. In the hyperarid Atacama Desert of northern Chile, many streams are characterized by perennial flow and support dense in-stream wetlands. These streams possess sequences of wetland deposits as fluvial terraces that record past changes in the water table. We mapped and radiocarbon dated a well-preserved sequence of in-stream wetland deposits along a 4.3-km reach of the Río San Salvador in the Calama basin to determine the relationship between regional climate change and the incision of in-stream wetlands. The Río San Salvador supported dense wetlands from 11.1 to 9.8, 6.4 to 3.5, 2.8 to 1.3, and 1.0 to 0.5 ka and incised at the end of each of these intervals. Comp...

Scientific Reports

Future climate change has the potential to alter the distribution and prevalence of plant pathoge... more Future climate change has the potential to alter the distribution and prevalence of plant pathogens, which may have significant implications for both agricultural crops and natural plant communities. However, there are few long-term datasets against which modelled predictions of pathogen responses to climate change can be tested. Here, we use 18S metabarcoding of 28 rodent middens (solidified deposits of rodent coprolites and nesting material) from the Central Atacama, spanning the last ca. 49 ka, to provide the first long-term late Quaternary record of change in plant pathogen communities in response to changing climate. Plant pathogen richness was significantly greater in middens deposited during the Central Andean Pluvial Event (CAPE); a period of increased precipitation between 17.5-8.5 ka. Moreover, the occurrence frequency of Pucciniaceae (rust fungi) was significantly greater during the CAPE, and the highest relative abundances for five additional potentially pathogenic taxa also occurred during this period. The results demonstrate the promising potential for ancient DNA analysis of late Quaternary samples to reveal insights into how plant pathogens responded to past climatic and environmental change, which could help predict how pathogens may responded to future change.

Scientific reports, Jan 12, 2018

Understanding the factors that modulate bacterial community assembly in natural soils is a longst... more Understanding the factors that modulate bacterial community assembly in natural soils is a longstanding challenge in microbial community ecology. In this work, we compared two microbial co-occurrence networks representing bacterial soil communities from two different sections of a pH, temperature and humidity gradient occurring along a western slope of the Andes in the Atacama Desert. In doing so, a topological graph alignment of co-occurrence networks was used to determine the impact of a shift in environmental variables on OTUs taxonomic composition and their relationships. We observed that a fraction of association patterns identified in the co-occurrence networks are persistent despite large environmental variation. This apparent resilience seems to be due to: (1) a proportion of OTUs that persist across the gradient and maintain similar association patterns within the community and (2) bacterial community ecological rearrangements, where an important fraction of the OTUs come t...

Current scientific evidence shows that humans colonized South America at least 15,000 years ago, ... more Current scientific evidence shows that humans colonized South America at least 15,000 years ago, but there are still many unknown aspects of this process, including the major and minor migratory routes involved, and the pattern of successive occupation of a diverse continental mosaic of ecosystems. In this context, the role of the Andean highlands (≥3400 meters above sea level) has been neglected, because of the supposedly harsh conditions for humans including hypoxia and cold climate. Nevertheless, the environmental and cultural resources available in the high Andes constitutes an important “megapatch” that should be assessed in terms of human settlement patterns. We review the evidence for late Pleistocene/early Holocene hunter-gatherer occupation of one part of this megapatch, the northern Chilean Dry Puna, in its palaeoecological context. We focus on lithic technology, faunal remains, radiocarbon dates, and other archaeological materials related to different social activities, w...

espanolLos grupos sociales que inicialmente habitaban el nucleo hiperarido del Desierto de Atacam... more espanolLos grupos sociales que inicialmente habitaban el nucleo hiperarido del Desierto de Atacama en el norte de Chile durante el Pleistoceno tardio integraron una amplia gama de bienes e ideas, locales, regionales y supra regionales, para su reproduccion social, como lo sugieren las evidencias arqueologicas materiales recuperadas en varios campamentos al aire libre en Pampa del Tamarugal (PdT). Los recursos locales para mantener su vida diaria, incluian materias primas liticas, fibras de plantas y animales, presas de caza y agua dulce adquiridos en un radio de -30 km (ca. 1-2 dias de viaje). A escala regional, se introdujeron algunos elementos desde la costa del Pacifico (60-80 km hacia el oeste, ca. 3 a 4 dias de viaje), incluidos rodados redondeados alargados, utilizados como percutores en la produccion litica y conchas, especialmente de especies no comestibles de moluscos. Desde los Andes (80-150 km al este, ca. 5-8 dias de viaje), obtuvieron fibra de camelido, obsidiana y una ...

Journal of Vertebrate Paleontology

ABSTRACT South America is well known for its abundance of Quaternary fossiliferous deposits, but ... more ABSTRACT South America is well known for its abundance of Quaternary fossiliferous deposits, but well-preserved fossil remains from well-dated sites are scarce in the Atacama Desert and adjacent arid Andes. Here we report on a partially complete skeleton (46%) of a single young (ca. 3–4 years old) extinct horse discovered in the Salar de Surire, a salt flat located on the Andean altiplano of northern Chile (4,250 m asl). Comparative and osteometric morphological analyses identify the specimen as a South American endemic horse Hippidion saldiasi Roth, 1899. A direct AMS radiocarbon date on bone collagen yielded a calibrated age of 13,170 cal yr BP (2σ range: 13,300–13,060 cal yr BP) indicating that it lived near the end of the last glaciation. The body mass of the individual was calculated at approximately 326.4 kg, close to the upper limit of the larger sizes reported for the genus. Stable isotope evidence shows that the Salar de Surire horse relied on an almost 100% C3 diet that is mostly consistent with Hippidion specimens from other environments that also consumed either mixed C3/C4 or fully C3 diets. This finding is now the southernmost high-elevation record for this species and provides further evidence for the broad geographic and ecological distribution of this genus throughout southern South America.

Science of The Total Environment

Nature Plants

The archaeological record shows that large pre-Inca agricultural systems supported settlements fo... more The archaeological record shows that large pre-Inca agricultural systems supported settlements for centuries around the ravines and oases of northern Chile’s hyperarid Atacama Desert. This raises questions about how such productivity was achieved and sustained, and its social implications. Using isotopic data of well-preserved ancient plant remains from Atacama sites, we show a dramatic increase in crop nitrogen isotope values (15N) from ~AD 1000. Maize was most affected, with 15N values as high as +30‰, with human bone collagen following a similar trend; moreover, their carbon isotope values (13C) indicate a considerable increase in the consumption of maize at the same time. We attribute the shift to extremely high 15N values – the highest in the world for archaeological plants – to the use of seabird guano to fertilise crops. Guano – “white gold” as it came to be called – thus sustained agricultural intensification, supporting a substantial population in an otherwise extreme environment.

Quaternary Science Reviews

Environmental Archaeology

Recovery methods and techniques for archaeological sampling can yield major differences in abunda... more Recovery methods and techniques for archaeological sampling can yield major differences in abundance and anatomo-taxonomical representation of animals, affecting past social and ecological reconstruction. Despite being a common organic material in archaeological sites, faunal remains typically exhibit differential preservation of species and skeletal elements due to pre-and post-depositional processes. This is particularly true for small-sized animals such as certain species of fish, whose often small and fragile fragments are difficult to recover and identify. Here, we present the results of a comparative analysis between two ichthyoarchaeological assemblages from Caleta Vitor 3 in northern Chile (CV3, 18°45 ′ 09 ′′ S), an Early to Middle Holocene (9.2-7.6 ka cal BP) Chinchorro shell midden site. We compare samples obtained and processed, both in the field and the lab, using different recovery techniques. We developed a data standardisation procedure to compare and evaluate skeletal representation, taxa distribution and variations throughout the stratigraphic sequence. Our results show that mesh screen size affects not only the abundance and density of fish but also species representation. Moreover, the identification of small pelagic fish at CV3 sheds further light upon prehistoric fishing strategies and social organisation during the site's early occupation.

Science of The Total Environment

Abstract Mining is a major industry in the Atacama Desert, one of the world's leading regions... more Abstract Mining is a major industry in the Atacama Desert, one of the world's leading regions for copper and other minerals. Intense industrialization of copper mining in the mid-twentieth century has likely led to significant environmental pollution through the deposition of heavy metals in the hyperarid Atacama, but how heavy metal pollution has changed over time in arid regions have rarely been assessed. Here, we analyzed both modern and ancient fecal pellets from paleomiddens collected in the central Atacama for heavy metals and by comparing current heavy metal concentrations with pre-industrial ones, we establish ecological baselines for such pollution. Sixteen paleomiddens spanning the last 1,000 years from multiple localities in the eastern Calama Basin (22°S) show elevated concentrations of Cu and As in modern compared to older middens, and that heavy metal, alkali metals and alkaline earth metals show positive correlations with each other. Heavy metals also tend to be higher in paleomiddens collected along perennial rivers in comparison to those collected from surrounding ranges, irrespective of sample age. Twenty paleomiddens spanning the last c. 16,000 years from a single locality (El Hotel) between the Calama and San Pedro de Atacama basins were used to establish long term variations in plant communities and associated heavy metals since the last glacial termination. Results show that heavy metal concentrations including Cr, Mo and B vary over time and tend to be higher in paleomiddens for which Cactaceae are more abundant whereas those dominated by annuals show less of an effect from trace metals. Our results imply that climate change-driven plant community composition plays a key role in explaining how contamination varies in these desert ecosystems and show that paleomiddens are a unique and unexplored source for understanding how heavy metals vary over time. Given their ubiquity in many of the world’s arid regions, they can be used to establish long-term ecological baselines to compare against human alterations.

Nature Plants, 2021

The archaeological record shows that large pre-Inca agricultural systems supported settlements fo... more The archaeological record shows that large pre-Inca agricultural systems supported settlements for centuries around the ravines and oases of northern Chile’s hyperarid Atacama Desert. This raises questions about how such productivity was achieved and sustained, and its social implications. Using isotopic data of well-preserved ancient plant remains from Atacama sites, we show a dramatic increase in crop nitrogen isotope values (15N) from ~AD 1000. Maize was most affected, with 15N values as high as +30‰, with human bone collagen following a similar trend; moreover, their carbon isotope values (13C) indicate a considerable increase in the consumption of maize at the same time. We attribute the shift to extremely high 15N values – the highest in the world for archaeological plants – to the use of seabird guano to fertilise crops. Guano – “white gold” as it came to be called – thus sustained agricultural intensification, supporting a substantial population in an otherwise extreme e...

PAGES news

A total of 25 students from six different countries were chosen from over 40 applicants to attend... more A total of 25 students from six different countries were chosen from over 40 applicants to attend the International Workshop on Methods in Quaternary Paleoecology. The majority of students were from either Argentina or Chile but other countries such as Colombia, Uruguay, France and Germany were also represented. Students participated in half-day lectures given by eight professors dealing with five major topics: Cathy Whitlock (USA) on charcoal records and analyses; Patricio Moreno (Chile), on high-resolution pollen records; Alan Cooper (Australia) on the extraction and analyses of fossil DNA; Ricardo Villalba (Argentina) on dendrochronology and dendroecology; Christopher Moy (USA) on new methods of radiocarbon and stable isotope analyses; Julio Betancourt (USA), Antonio Maldonado (Chile) and Claudio Latorre (Chile) on methods, analyses and case studies in arid lands paleoecology. The course also involved several laboratory demonstrations involving charcoal analyses, coring equipment, tree rings and rodent middens from the Atacama Desert. Aside from the lectures, students were also given the opportunity of presenting their work as talks and posters, followed by comments on methods and results from the course professors and attendees. These presentations dealt with a variety of topics on South American paleoclimatology, paleoecology, biogeography, and archeology using a diverse array of methods and proxies. Among these were fossil pollen records, rodent middens, diatoms, chironomids, phytoliths, dendrochronology, glacial geology and modern analogue techniques. Research covered a vast geographic area, ranging from the Bogotá wetlands in Colombia to the southern cone of South America, along the Atlantic coast of Uruguay and Argentina, as well as the Bolivian Altiplano and the coastal Atacama Desert along the Pacific coast down to the Patagonian icefields. This lively round of discussions and the high quality presentations stimulated interactions not only between students and professors, but also kindled possible interactions among students from different countries.

Vegetation History and Archaeobotany

Throughout Earth's most extreme environments, such as the Kalahari Desert or the Arctic, ... more Throughout Earth's most extreme environments, such as the Kalahari Desert or the Arctic, hunter-gatherers found ingenious ways to obtain proteins and sugars provided by plants for dietary requirements. In the hyperarid Atacama Desert, wild plant resources are scarce and unevenly distributed due to limited water availability. This study brings together all available archaeobotanical evidence gathered in the Atacama Desert from the Late Pleistocene (ca. 13,000 cal bp) until the Inka epoch (ca. 450 cal bp) to help us comprehend when these populations acquired and managed useful plants from the coastal zone, Intermediate Depression, High Andes, as well as tropical and subtropical ecosystems. Widespread introduction of farming crops, water control techniques and cultivation of diverse plants by 3,000 cal bp ended not only a chronic food shortage, but also led to the establishment of a set of staple foods for the Atacama Desert dwellers, a legacy that remains visible today. By contrasting these trends with major sociocultural changes, together with palaeodemographic and climatic fluctuations, we note that humans adapted to, and transformed this hyperarid landscape and oscillating climate, with plants being a key factor in their success. This long-term process, which we term the "Green Revolution", coincided with an exponential increase in the number of social groups inhabiting the Atacama Desert during the Late Holocene.

Vegetation History and Archaeobotany, 2020

Throughout Earth's most extreme environments, such as the Kalahari Desert or the Arctic, hunt... more Throughout Earth's most extreme environments, such as the Kalahari Desert or the Arctic, hunter-gatherers found ingenious ways to obtain proteins and sugars provided by plants for dietary requirements. In the hyperarid Atacama Desert, wild plant resources are scarce and unevenly distributed due to limited water availability. This study brings together all available archaeobotanical evidence gathered in the Atacama Desert from the Late Pleistocene (ca. 13,000 cal bp) until the Inka epoch (ca. 450 cal bp) to help us comprehend when these populations acquired and managed useful plants from the coastal zone, Intermediate Depression, High Andes, as well as tropical and subtropical ecosystems. Widespread introduction of farming crops, water control techniques and cultivation of diverse plants by 3,000 cal bp ended not only a chronic food shortage, but also led to the establishment of a set of staple foods for the Atacama Desert dwellers, a legacy that remains visible today. By contras...

Scientific Reports

Human activities have profoundly altered the global nutrient cycle through Land Use and Cover Cha... more Human activities have profoundly altered the global nutrient cycle through Land Use and Cover Changes (LUCCs) since the industrial revolution and especially during the Great Acceleration (1950 CE). Yet, the impact of such activities on terrestrial and aquatic ecosystems above their ecological baselines are not well known, especially when considering the response of these systems to the intensity of LUCCs on nutrient cycles. Here, we used a multiproxy approach (sedimentological, geochemical and isotopic analyses, historical records, climate data, and satellite images) to evaluate the role that LUCCs have on Nitrogen (N) cycling in a coastal mediterranean watershed system of central Chile over the last two centuries. Despite long-term anthropogenic use (agriculture, cattle grazing) in the Matanzas watershed– lake system, these LUCC appear to have had little impact on nutrient and organic matter transfer since the Spanish Colonial period. In contrast, the largest changes in N dynamics ...

Quaternary Science Reviews

Abstract Paleoparasitology offers a window into prehistoric parasite faunas, and through studying... more Abstract Paleoparasitology offers a window into prehistoric parasite faunas, and through studying time-series of parasite assemblages it may be possible to observe how parasites responded to past environmental or climate change, or habitat loss (host decline). Here, we use DNA metabarcoding to reconstruct parasite assemblages in twenty-eight ancient rodent middens (or paleomiddens) from the central Atacama Desert in northern Chile. The paleomiddens span the last 50,000 years, and include middens deposited before, during and after the Central Andean Pluvial Event (CAPE; 17.5–8.5 ka BP). The CAPE was a period of increased precipitation and vegetation change, which we also demonstrate was associated with changes in local rodent taxa. Thirteen parasite taxa (including lice, mites, ticks, nematodes and coccidians) were identified from the middens, nine of which were likely derived from rodent hosts and four from alternative (insect or avian) hosts. The former are consistent with parasites known to infect South American rodent hosts. At our conservative level of high taxonomic rank assignment, the parasites appear to have been resilient to the major perturbations in climate and host taxa associated with the CAPE, and finer taxonomic resolution would be required to detect whether any species turnover occurred within the identified parasite groups. Rodent paleomiddens are fast becoming an unrivaled source of genomic data that can be used to reconstruct past ecosystem change on multiple taxonomic, temporal and spatial scales providing new insights into ecological responses to global change.

Frontiers in Earth Science

Quaternary Research

A key concern regarding current and future climate change is the possibility of sustained drought... more A key concern regarding current and future climate change is the possibility of sustained droughts that can have profound impacts on societies. As such, multiple paleoclimatic proxies are needed to identify megadroughts, the synoptic climatology responsible for these droughts, and their impacts on past and future societies. In the hyperarid Atacama Desert of northern Chile, many streams are characterized by perennial flow and support dense in-stream wetlands. These streams possess sequences of wetland deposits as fluvial terraces that record past changes in the water table. We mapped and radiocarbon dated a well-preserved sequence of in-stream wetland deposits along a 4.3-km reach of the Río San Salvador in the Calama basin to determine the relationship between regional climate change and the incision of in-stream wetlands. The Río San Salvador supported dense wetlands from 11.1 to 9.8, 6.4 to 3.5, 2.8 to 1.3, and 1.0 to 0.5 ka and incised at the end of each of these intervals. Comp...

Scientific Reports

Future climate change has the potential to alter the distribution and prevalence of plant pathoge... more Future climate change has the potential to alter the distribution and prevalence of plant pathogens, which may have significant implications for both agricultural crops and natural plant communities. However, there are few long-term datasets against which modelled predictions of pathogen responses to climate change can be tested. Here, we use 18S metabarcoding of 28 rodent middens (solidified deposits of rodent coprolites and nesting material) from the Central Atacama, spanning the last ca. 49 ka, to provide the first long-term late Quaternary record of change in plant pathogen communities in response to changing climate. Plant pathogen richness was significantly greater in middens deposited during the Central Andean Pluvial Event (CAPE); a period of increased precipitation between 17.5-8.5 ka. Moreover, the occurrence frequency of Pucciniaceae (rust fungi) was significantly greater during the CAPE, and the highest relative abundances for five additional potentially pathogenic taxa also occurred during this period. The results demonstrate the promising potential for ancient DNA analysis of late Quaternary samples to reveal insights into how plant pathogens responded to past climatic and environmental change, which could help predict how pathogens may responded to future change.

Scientific reports, Jan 12, 2018

Understanding the factors that modulate bacterial community assembly in natural soils is a longst... more Understanding the factors that modulate bacterial community assembly in natural soils is a longstanding challenge in microbial community ecology. In this work, we compared two microbial co-occurrence networks representing bacterial soil communities from two different sections of a pH, temperature and humidity gradient occurring along a western slope of the Andes in the Atacama Desert. In doing so, a topological graph alignment of co-occurrence networks was used to determine the impact of a shift in environmental variables on OTUs taxonomic composition and their relationships. We observed that a fraction of association patterns identified in the co-occurrence networks are persistent despite large environmental variation. This apparent resilience seems to be due to: (1) a proportion of OTUs that persist across the gradient and maintain similar association patterns within the community and (2) bacterial community ecological rearrangements, where an important fraction of the OTUs come t...