Andean Altiplano Research Articles

The status quo effect in the sociohydrology of floods

ABSTRACT Two behavioural types in sociohydrology of floods have been described in more detail than others: the levee effect and the learning effect. However, additional types of behaviour operate and need further research. Taking the case of frequent flash floods occurring in an ephemeral stream, a tributary of the Vilama River, located in San Pedro de Atacama, Chile, at the interphase between the Atacama desert and the Andean Altiplano, we explore the existence of further behavioural types in the sociohydrology of floods at four neighbourhoods along the tributary. Fieldwork to reconstruct a recent flood event, hydrological analysis and semistructured interviews with key informants to characterize people’s responses to floods were conducted. Results show evidence that the so-called status quo effect is present at the riparian community scale, i.e. when communities do not learn and adapt to prevent damage even when exposed to frequent floods. Possible causes of the status quo effect are discussed.

Unveiling the Wing Shape Variation in Northern Altiplano Ecosystems: The Example of the Butterfly Phulia nymphula Using Geometric Morphometrics

The Andean Altiplano, characterized by its extreme climatic conditions and high levels of biodiversity, provides a unique environment for studying ecological and evolutionary adaptations in insect morphology. Butterflies, due their large wing surface compared to body surface, and wide distribution among a geographical area given the flight capabilities provided by their wings, constitute a good biological model to study morphological adaptations following extreme weathers. This study focuses on Phulia nymphula, a butterfly species widely distributed in the Andes, to evaluate wing shape variation across six localities in the Northern Chilean Altiplano. The geometric morphometrics analysis of 77 specimens from six locations from the Chilean Altiplano (Caquena, Sorapata Lake, Chungará, Casiri Macho Lake, Surire Salt Flat, and Visviri) revealed significant differences in wing shape among populations. According to the presented results, variations are likely influenced by local environmental conditions and selective pressures, suggesting specific adaptations to the microhabitats of the Altiplano. The first three principal components represented 60.92% of the total wing shape variation. The detected morphological differences indicate adaptive divergence among populations, reflecting evolutionary responses to the extreme and fragmented conditions of the Altiplano. This study gives insights into the understanding of how high-altitude species can diversify and adapt through morphological variation, providing evidence of ecological and evolutionary processes shaping biodiversity in extreme environments.

Participación política de la mujer en los Andes

The women of the Andes serve as a testament to resilience and fortitude in the face of constraints imposed by social structures and stereotypes. The objective of this study is to analyze the narratives employed by women leaders regarding women’s political participation in the Andes. A qualitative methodology based on a hermeneutic-dialogical foundation was employed, whereby eight women of andean altiplano origin were interviewed using an in-depth interview guide. The questions addressed the following categories: the right to be elected, the role of women in political participation, and the obstacles faced by women in the political environment. As a result, a number of emerging subcategories were identified, including gender participatory democracy, the evolution of female political principles, the characteristics of a female leader, the socio-political aspects of women, the marginalization of women, the transition to female management, gender-related obstacles, and female vindication. These subcategories provide insight into the challenges faced by women in the struggle against sexual harassment, gender-based violence, and all forms of discrimination. They highlight the need for the development of inclusive and ethical systems that promote the rights of the gender in question.

Species limits and hybridization in Andean leaf-eared mice (Phyllotis).

Leaf-eared mice (genus Phyllotis) are among the most widespread and abundant small mammals in the Andean Altiplano, but species boundaries and distributional limits are often poorly delineated due to sparse survey data from remote mountains and high-elevation deserts. Here we report a combined analysis of mitochondrial DNA variation and whole-genome sequence (WGS) variation in Phyllotis mice to delimit species boundaries, to assess the timescale of diversification of the group, and to examine evidence for interspecific hybridization. Estimates of divergence dates suggest that most diversification of Phyllotis occurred during the past 3 million years. Consistent with the Pleistocene Aridification hypothesis, our results suggest that diversification of Phyllotis largely coincided with climatically induced environmental changes in the mid- to late Pleistocene. Contrary to the Montane Uplift hypothesis, most diversification in the group occurred well after the major phase of uplift of the Central Andean Plateau. Species delimitation analyses revealed surprising patterns of cryptic diversity within several nominal forms, suggesting the presence of much undescribed alpha diversity in the genus. Results of genomic analyses revealed evidence of ongoing hybridization between the sister species Phyllotis limatus and P. vaccarum and suggest that the contemporary zone of range overlap between the two species represents an active hybrid zone.

Hyperexpansion of genetic diversity and metabolic capacity of extremophilic bacteria and archaea in ancient Andean lake sediments

BackgroundThe Andean Altiplano hosts a repertoire of high-altitude lakes with harsh conditions for life. These lakes are undergoing a process of desiccation caused by the current climate, leaving terraces exposed to extreme atmospheric conditions and serving as analogs to Martian paleolake basins. Microbiomes in Altiplano lake terraces have been poorly studied, enclosing uncultured lineages and a great opportunity to understand environmental adaptation and the limits of life on Earth. Here we examine the microbial diversity and function in ancient sediments (10.3–11 kyr BP (before present)) from a terrace profile of Laguna Lejía, a sulfur- and metal/metalloid-rich saline lake in the Chilean Altiplano. We also evaluate the physical and chemical changes of the lake over time by studying the mineralogy and geochemistry of the terrace profile.ResultsThe mineralogy and geochemistry of the terrace profile revealed large water level fluctuations in the lake, scarcity of organic carbon, and high concentration of SO42--S, Na, Cl and Mg. Lipid biomarker analysis indicated the presence of aquatic/terrestrial plant remnants preserved in the ancient sediments, and genome-resolved metagenomics unveiled a diverse prokaryotic community with still active microorganisms based on in silico growth predictions. We reconstructed 591 bacterial and archaeal metagenome-assembled genomes (MAGs), of which 98.8% belonged to previously unreported species. The most abundant and widespread metabolisms among MAGs were the reduction and oxidation of S, N, As, and halogenated compounds, as well as aerobic CO oxidation, possibly as a key metabolic trait in the organic carbon-depleted sediments. The broad redox and CO2 fixation pathways among phylogenetically distant bacteria and archaea extended the knowledge of metabolic capacities to previously unknown taxa. For instance, we identified genomic potential for dissimilatory sulfate reduction in Bacteroidota and α- and γ-Proteobacteria, predicted an enzyme for ammonia oxidation in a novel Actinobacteriota, and predicted enzymes of the Calvin–Benson–Bassham cycle in Planctomycetota, Gemmatimonadota, and Nanoarchaeota.ConclusionsThe high number of novel bacterial and archaeal MAGs in the Laguna Lejía indicates the wide prokaryotic diversity discovered. In addition, the detection of genes in unexpected taxonomic groups has significant implications for the expansion of microorganisms involved in the biogeochemical cycles of carbon, nitrogen, and sulfur.EPcqnK6xUD66cr6MUL2q3UVideo

Arsenic, selenium, and mercury speciation in hypersaline lakes of the Andean Altiplano: Link between extreme levels and biodiversity repartition

Arsenic (As) and mercury (Hg) are highly toxic contaminants whereas selenium (Se) is both an essential trace element and potentially harmful at higher concentrations. The hyper-saline lakes of southern Bolivian Altiplano, which are ecological niches for endemic species, are also expected to be enriched in these toxic trace elements. The biogeochemistry of As, Hg, and Se in such high-altitude extreme environments (e.g., high UV radiation and salt content) remains poorly understood. In this study, we investigated the concentrations and chemical forms (speciation) of As, Hg, and Se in sediment, water, and air samples of Lagunas Colorada (LC), Verde (LV), and Blanca (LB) in the South Lipez region (>4200 m a.s.l.). We compared them with the repartition of biodiversity (invertebrates, algae, and bacteria). Extreme As concentrations were found in water (up to 82 mg L−1), and the main As species was inorganic As(V), with neither biogenic methylated As nor volatile As forms being detected in water and air, respectively. Se concentrations in water were of 0.1 to 1.4 μg L−1, and Se existed under different redox states, i.e., Se(IV), Se(VI), and reduced Se (0, -II), including biogenic methylated Se(-II) (trimethyl selenonium). Volatile Se compounds (e.g., dimethyl selenide) were detected in water and air samples. Hg was enriched in the surface water (6 to 30 ng L−1) compared to other regional water bodies, and a significant amount of methyl-Hg and gaseous Hg(0) was detected. The drastic disparity between As, Se and Hg concentrations and speciation between lakes has important implications for their cycling in these extreme aquatic systems. While As mostly accumulated in its oxidized and non-volatile form, Hg and Se concentrations can be controlled by significant conversion to reduced and methylated forms, allowing efficient evasion to the atmosphere. Finally, the salinity, including major ions, and high levels of As were among the main drivers of biodiversity repartition between lakes.

Pre-hispanic wetland irrigation and metallurgy in the South Andean Altiplano (Intersalar Region, Bolivia, XIVth and XVth century CE)

The high-altitude Andean Altiplano has been subject to abrupt climate changes during the Holocene. The resulting impact on the hydrological cycle has obliged ancient societies to adapt and develop strategies to face droughts and sustain agropastoral activities. Here, we present the results of archaeological prospections together with the biogeochemical characterization of a well-dated core collected at Saitoco wetland in the arid southern Altiplano (Intersalar Region, Bolivia). Archaeological survey allowed the mapping of a network of channels collecting water from the surrounding mountains to the wetland, and the presence of small copper mines and metallurgical installations. Traces and major element concentrations and accumulation rates, together with elemental and isotopic characterization of organic matter (OM) (i.e., Corg and δ13Corg) in the wetland core have been used to document the evolution of the landscape in relation to climatic and anthropogenic pressure. While OM, bromine (Br), selenium (Se) and mercury (Hg) data were used to assess the variability of precipitations during the Late Holocene (4.2 ka BP to the present), local and regional mining activities have been reconstructed through the variations of lead (Pb), copper (Cu), and antimony (Sb). Our results show an abrupt change in OM composition during the 14th and 15th century CE, characterized by an abrupt shift in δ13Corg synchronous with a rise in Br, Se and Hg, testifying for the waterlogging of the wetland during a known arid period in the region. This change is attributed to anthropogenic transformation of the landscape through the irrigation of the wetland by channeling streams from the surrounding mountains. At the same time, a mining pollution signal was recorded supporting local Cu mining and metallurgy. The mining signal then reached its maximum values during the Inca and Colonial periods, which matches with reported enhanced mining activities in the region. From the colonial era onward, the wetland progressively dried up, likely resulting from the abandonment of the site. Through the combination of a biogeochemical record and archaeological prospections, this study provides evidences that societies of the arid Intersalar region have transformed their landscape and developed wetland irrigation and mining during the arid 14th and 15th century CE Period.

Genomes of the Orestias pupfish from the Andean Altiplano shed light on their evolutionary history and phylogenetic relationships within Cyprinodontiformes

BackgroundTo unravel the evolutionary history of a complex group, a comprehensive reconstruction of its phylogenetic relationships is crucial. This requires meticulous taxon sampling and careful consideration of multiple characters to ensure a complete and accurate reconstruction. The phylogenetic position of the Orestias genus has been estimated partly on unavailable or incomplete information. As a consequence, it was assigned to the family Cyprindontidae, relating this Andean fish to other geographically distant genera distributed in the Mediterranean, Middle East and North and Central America. In this study, using complete genome sequencing, we aim to clarify the phylogenetic position of Orestias within the Cyprinodontiformes order.ResultsWe sequenced the genome of three Orestias species from the Andean Altiplano. Our analysis revealed that the small genome size in this genus (~ 0.7 Gb) was caused by a contraction in transposable element (TE) content, particularly in DNA elements and short interspersed nuclear elements (SINEs). Using predicted gene sequences, we generated a phylogenetic tree of Cyprinodontiformes using 902 orthologs extracted from all 32 available genomes as well as three outgroup species. We complemented this analysis with a phylogenetic reconstruction and time calibration considering 12 molecular markers (eight nuclear and four mitochondrial genes) and a stratified taxon sampling to consider 198 species of nearly all families and genera of this order. Overall, our results show that phylogenetic closeness is directly related to geographical distance. Importantly, we found that Orestias is not part of the Cyprinodontidae family, and that it is more closely related to the South American fish fauna, being the Fluviphylacidae the closest sister group.ConclusionsThe evolutionary history of the Orestias genus is linked to the South American ichthyofauna and it should no longer be considered a member of the Cyprinodontidae family. Instead, we submit that Orestias belongs to the Orestiidae family, as suggested by Freyhof et al. (2017), and that it is the sister group of the Fluviphylacidae family, distributed in the Amazonian and Orinoco basins. These two groups likely diverged during the Late Eocene concomitant with hydrogeological changes in the South American landscape.

Growing in Scarcity: Pre-Hispanic Rain-Fed Agriculture in the Semi-Arid and Frost-Prone Andean Altiplano (Bolivia)

Ancient Andean agricultural landscapes have been the subject of a large number of archaeological and agro-ecological studies, which generally refer to regions with favourable environmental conditions or, in the case of arid and semi-arid environments, those with irrigation facilities. The aim of this article is to present and analyse the pre-Hispanic rain-fed farming systems widely represented in two adjacent regions of Bolivia’s arid and cold southern Altiplano. The search for archaeological agricultural areas combined aerial analysis and field surveys. Agro-ecological characterisation was based on historical and ethnographic studies of the region’s present-day populations. Despite their geographical proximity, similar environmental conditions, and same agropastoral way of life, the typology of cultivated areas developed in the southern altiplano differs significantly. Within this same framework of adaptation and resilience, the sectorisation of agricultural systems observed in these two regions reveals a regional productive specialisation that favoured internal exchanges and exchanges with other regions. These differences are related to two models of non-centralised, low-inequality societies—one strongly based on cohesion and the other characterised by greater fragmentation and social conflict—underlining the limits of strict environmental determinism in shaping agricultural landscapes. These results provide new food for thought in the debate on the use and value of rain-fed agricultural practices and more broadly on the diversity of adaptations by human societies in extreme and unstable environmental contexts.

Exploring the prokaryote-eukaryote interplay in microbial mats from an Andean athalassohaline wetland.

Microbial community assembly results from the interaction between biotic and abiotic factors. However, environmental selection is thought to predominantly shape communities in extreme ecosystems. Salar de Huasco, situated in the high-altitude Andean Altiplano, represents a poly-extreme ecosystem displaying spatial gradients of physicochemical conditions. To disentangle the influence of abiotic and biotic factors, we studied prokaryotic and eukaryotic communities from microbial mats and underlying sediments across contrasting areas of this athalassohaline ecosystem. The prokaryotic communities were primarily composed of bacteria, notably including a significant proportion of photosynthetic organisms like Cyanobacteria and anoxygenic photosynthetic members of Alpha- and Gammaproteobacteria and Chloroflexi. Additionally, Bacteroidetes, Verrucomicrobia, and Deltaproteobacteria were abundantly represented. Among eukaryotes, photosynthetic organisms (Ochrophyta and Archaeplastida) were predominant, alongside relatively abundant ciliates, cercozoans, and flagellated fungi. Salinity emerged as a key driver for the assembly of prokaryotic communities. Collectively, abiotic factors influenced both prokaryotic and eukaryotic communities, particularly those of algae. However, prokaryotic communities strongly correlated with photosynthetic eukaryotes, suggesting a pivotal role of biotic interactions in shaping these communities. Co-occurrence networks suggested potential interactions between different organisms, such as diatoms with specific photosynthetic and heterotrophic bacteria or with protist predators, indicating influences beyond environmental selection. While some associations may be explained by environmental preferences, the robust biotic correlations, alongside insights from other ecosystems and experimental studies, suggest that symbiotic and trophic interactions significantly shape microbial mat and sediment microbial communities in this athalassohaline ecosystem.IMPORTANCEHow biotic and abiotic factors influence microbial community assembly is still poorly defined. Here, we explore their influence on prokaryotic and eukaryotic community assembly within microbial mats and sediments of an Andean high-altitude polyextreme wetland system. We show that, in addition to abiotic elements, mutual interactions exist between prokaryotic and eukaryotic communities. Notably, photosynthetic eukaryotes exhibit a strong correlation with prokaryotic communities, specifically diatoms with certain bacteria and other protists. Our findings underscore the significance of biotic interactions in community assembly and emphasize the necessity of considering the complete microbial community.

Stable isotope chemistry reveals plant-dominant diet among early foragers on the Andean Altiplano, 9.0-6.5 cal. ka.

Current models of early human subsistence economies suggest a focus on large mammal hunting. To evaluate this hypothesis, we examine human bone stable isotope chemistry of 24 individuals from the early Holocene sites of Wilamaya Patjxa (9.0-8.7 cal. ka) and Soro Mik'aya Patjxa (8.0-6.5 cal. ka) located at 3800 meters above sea level on the Andean Altiplano, Peru. Contrary to expectation, Bayesian mixing models based on the isotope chemistry reveal that plants dominated the diet, comprising 70-95% of the average diet. Paleoethnobotanical data further show that tubers may have been the most prominent subsistence resource. These findings update our understanding of earliest forager economies and the pathway to agricultural economies in the Andean highlands. The findings furthermore suggest that the initial subsistence economies of early human populations adapting to new landscapes may have been more plant oriented than current models suggest.

Knowledge Management: The Siku, an Aboriginal Aymara Ethnic Group and Cultural Heritage of the Andean Highlands

Objective: The study aims to apply the models proposed in Knowledge Management (KM) for the rescue of the cultural heritage of the Siku instrument, with the Peruvian Altiplano as a scenario. Theoretical Framework: The siku originates from the Aymara people and is a cultural manifestation rooted in the Andean highlands. It is considered a gift from Mother Earth and symbolizes the connection between the human being and the sounds it emanates. Method: The methodological approach was approached from a qualitative perspective, using the ethnomethodological method through an inductive approach. We worked with two groups of participants, the first one composed of four members of the Conjunto de Arte y Folklore Sicuris "Juventud Obrera", who are considered heirs of the Aymara tradition; and the second one was constituted by six young people from the urbanization El Progreso, who reflected on the meaning of the cultural heritage of the native peoples in the Andes. Results: The results are presented in two categories: a) diagnosis, b) final assessment, where a real socio-critical transformation mediated by adequate QA can be observed. Conclusions: It highlights on a large scale the role of the Siku as an aboriginal Aymara ethnic group and cultural heritage of the Andean Altiplano; likewise, by way of projection, three essential questions stand out, which are: what measures can the State take to rescue Peru's ancestral traditions? What programs can be developed through education so that society appropriates the millenary cultural heritage? Could this experience be replicated in other aboriginal communities with other thematic approaches?

Diet Digestibility and Partitioning of Nutrients in Adult Male Alpacas Fed a Blend of Oat Hay and Alfalfa Pellets at Two Levels of Intake

Alpacas are well adapted to consume the poor-quality forages present in the arid conditions of the Andean Altiplano. However, studies focusing on understanding the relationship between diet digestibility and intake are scarce. The aim of this study was to evaluate the effects of two levels of dry matter intake (DMI) on a metabolic body weight (BW0.75) basis. The effects of a maintenance level of intake and an ad libitum level of intake (40 and 50 g of dry matter (DM) per kg of BW0.75, respectively) on the apparent diet digestibility and partitioning of specific nutrients (energy, carbon (C), and nitrogen (N)) of alpacas that were fed a blend of oat hay and alfalfa pellets (70:30 ratio as a percentage on a fed basis) were evaluated. Five adult intact male alpacas (BW = 62.9 ± 8.09 kg at the beginning of the study) were fed with the experimental diet and trained to be allocated in metabolism crates for 30 days. After the completion of this phase, two separate experiments for each level of intake were carried out, each lasting for twenty-six days (with the final five days taken for samples and raw data collection). In both experiments, the animals responded differently in terms of nutrient supply and changes in BW (−140 and 100 g/d for the maintenance and ad libitum levels of intake, respectively). Oat hay consumption was rather similar in both experiments, which may be explained by a reduced ingredient selectivity at the ad libitum level of intake. Diet digestibility was similar in both experiments, despite the greater fecal output of nutrients with the increased level of diet intake. In line with this, diet metabolizability, calculated as the ratio between metabolizable energy (ME) and gross energy (GE) contents, indicated a similar energy utilization of the diet. The apparent digestibility of the organic matter (OMD) ranged from 655 to 669 g/kg DM. Water consumption at the ad libitum level of intake was 21% higher than the observed mean at the maintenance level of intake. Fecal outputs of dietary energy, C, and N accounted for the largest source of excreted nutrients, regardless of the level of intake. The N retention increased from 0.439 at the maintenance level of intake, to 0.473 g of DM/kg BW0.75 when the alpacas were fed ad libitum.

Novel cercozoan and heterolobosean protists from the rhizosphere and phyllosphere of two endemic cacti from the Atacama Desert

Cercozoans and heterolobose amoebae are found across terrestrial habitats where they feed on other unicellular microbes, including bacteria, fungi and microalgae. They constitute a significant fraction of soil ecosystems and are integral members of plant microbiota. Here, we present the results on the isolation of protozoans from the rhizosphere and phyllosphere of Browningia candelaris (Meyen) in the Andean Altiplano and Eulychnia taltalensis (F. Ritter) from the Coastal Cordillera of the Atacama Desert, both endemic to this ancient desert. We identified a new heterolobose amoeba species of the genus Allovahlkampfia isolated from cactus soil, three new species of the different glissomonad genera Allapsa, Neoheteromita, Neocercomonas and one new thecofilosean amoeba of the genus Rhogostoma isolated from the phyllosphere of one studied cactus. In addition, one bacterivorous flagellate was isolated from cactus spines and identified as a member of the non-scaled imbricatean family Spongomonadidae (Spongomonas). The isolation of protists from cactus spines extends the knowledge on the habitat ranges of taxa typically found on plant leaves or soils. The molecular data presented here is a prerequisite for further investigations on the ecology and diversity of protists including next-generation sequencing of microhabitats in plants and the rhizosphere, allowing for deeper taxonomic classification.

Hydrological modeling of the Silala River basin. 1. Model development and long‐term groundwater recharge assessment

AbstractThe Silala is a small river, originating in the Andean Altiplano, which flows from Bolivia into Chile. Prior to a legal dispute between Chile and Bolivia over the status and use of the waters of the Silala, few hydrological studies had been performed in the basin. Further insights were required to better understand the surface‐water and groundwater discharges from Bolivia to Chile, and the effects of historical channelization of the Bolivian wetlands on these flows. A semi‐distributed hydrological model was therefore developed to estimate the discharges from the basin and provide recharge inputs to a groundwater model used to investigate the effects of channelization. Long‐term temperature and precipitation data were available for 1969–1992, while more detailed data were available for 2018–2019. 1969–1992 was selected as a suitable length of record for long‐term groundwater recharge estimation, and the recent data were reserved for model validation, reported in a companion paper. Prior model parameter ranges were identified based on field observations and scientific literature, and sampling of both input and parameter uncertainty allowed determination of representative, lower and upper groundwater recharge scenarios. Results show strong inter‐annual and seasonal variability, the largest groundwater recharge being observed during the Austral summer. A representative groundwater recharge rate of 39.5 mm/year was obtained for the basin to the international border, with feasible lower and upper bounds of 34.9 and 50.2 mm/year, respectively. This lies within the range of 21–51 mm/year estimated by Bolivia for 1969–2017, albeit higher than their best estimate (24 mm/year).This article is categorized under: Science of Water > Hydrological Processes

Elevational range extension of the Puna Mouse, Punomys (Cricetidae), with the first record of the genus from Chile.

We report an elevational record for the Andean sigmodontine Puna Mouse Punomys, which is also the first record of the genus in Chile. The record is based on a mummified specimen that we discovered at an elevation of 5,461 m (17,917 feet) in the caldera of Volcán Acamarachi, Región de Antofagasta, Chile. Results of a morphological assessment suggest that the specimen can be provisionally referred to the species P. lemminus. This new record also extends the known geographic distribution of the genus by 700 km to the south and brings the known Chilean mammal richness to a total of 170 living species and 88 genera. This finding highlights the need for increased survey efforts in more remote, high-elevation regions and demonstrates that there is still much to be learned about the mammal fauna of the Andean Altiplano.

The archaeology of human permanency on the Tibetan plateau: a critical review and assessment of current models

High-elevation (>2500 m a.s.l.) environments pose severe challenges for human adaptation, and the timing and catalysts of their sustained year-round occupation remain a matter of debate. This article reviews recent archaeological and genetic research on the peopling of the Tibetan Plateau, and presents the results of new least cost path modeling. It is argued that permanent occupation by foragers before the Holocene was possible and that the concept of “permanency” needs clarification. Evidence for the persistence of indigenous populations and traditional foraging economies after the introduction of domesticates further suggests that diffusionist views treating the Plateau's indigenous societies as passive recipients of memes and genes should be abandoned. The diverse topographies, ecosystems, and cultural traditions found within and surrounding the Plateau hold potential for having offered multiple pathways to food production and attendant societal interactions. Recent discoveries from the Gebusailu Cemetery suggest that such potential is particularly high for the western Plateau given its biographic extremity and pivotal position between complex polities in Central and northeast South Asia. Through comparison with archaeological materials from the Ethiopian Highlands and Andean Altiplano, it is further suggested that hunter-gatherers sustained year-round occupations in the Plateau's interior during the Pleistocene and early Holocene, and that the emergence of domestication played a significant role in promoting the large-scale peopling of high-altitudes. Long-term interactions between indigenous peoples and newcomers contributed to the formation of Plateau civilizations.

O11 Botanical composition and nutritional chemistry of the diet of llamas from Andean Altiplano grazing native grassland

O11 Botanical composition and nutritional chemistry of the diet of llamas from Andean Altiplano grazing native grassland

Pucara Hilltop Settlements in the Lupaca and Pacajes Territories, Southern Andean Altiplano, during the Late Intermediate Period (AD 1000–1450)

AbstractThe quantity of archaeological data for the fortified hilltop settlements of the Late Intermediate period on the Andean altiplano, called pucaras, varies greatly. Some areas, such as the territory of the Colla Aymara chieftaincy east of Lake Titicaca, are well documented thanks to recent and exhaustive research. Other areas, such as the territories of the Lupacas and the Pacajes, are much less documented. From comparative spatial analyses of satellite images from these two territories, we obtained new data on pucaras, whose characteristics seem to differ from those proposed in the archaeological literature. Through a combination of fieldwork and spatial analysis of 295 pucaras, we identified 252 unpublished sites and propose a new typology comprising four categories. Based on ethnohistoric data and the results of the architectural and geographical analyses, we discuss the possible motivations for building so many pucaras; we suggest that some reasons are of a symbolic nature.

Sustainability of Animal Stocks in Traditional Pastoral Systems of the High-Altitude Andean Altiplano

The main traditional livelihood in the high Central Andes Plateau, locally known as the Puna, is pastoralism. This system is based on llamas (Lama glama) and sheep (Ovis aries), which graze on natural vegetation (shrub steppe, grasslands, and peatlands). So, the livelihood of Andean communities is strongly influenced by the spatial and temporal dynamics of vegetation. Most of the existing models on herbivory used to estimate sustainable livestock loads require information on the nutritional values and primary production of vegetation, which is lacking for the Argentine Puna. This work aimed to fill the gap by implementing a carrying capacity model using data on annual vegetation growth and herbivore feeding strategies collected in the field in different plant communities. The hypothesis that guided this work was that environmental heterogeneity affects management decisions and should be taken into account to model sustainable animal stocks in Andean pastoralist systems. We estimated carrying capacity based on the MSY logistic model, considering biomass and aboveground primary production of vegetation communities, climatic features, and herbivore selective responses. We compared the estimated carrying capacity with real animal stocks in four production units within the study site in 2013, 2014, and 2017. The results indicate that the carrying capacity presents high spatial and temporal variability. In three of the production units assessed, the livestock—mixed herds of sheep and llamas—were above or near the estimated carrying capacity, even when the stocking rates were reduced during dry periods. The high stocking rates, along with evidence of land degradation, may indicate moderate to severe overgrazing. This work demonstrates the usefulness of estimating the carrying capacity to monitor the pastoral systems at fine space and time scales. These monitoring techniques can facilitate decision making among Puna herders in a biocultural context of knowledge dialog that may foster sustainability in pastoralist livelihoods.