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The Late-Holocene history of hydroclimatic variability in the Atacama Desert offers insights into the effects of precipitation and humans on ecosystems in one of the most extremely arid regions of the world. However, understanding the effects of regional precipitation variability in relation to local ecological stressors remains to be fully resolved. Here, we present a pollen-based qualitative precipitation reconstruction derived from fossil rodent middens recovered from two sites near Laguna Roja (LRO; n = 25) and Isluga (ISL; n = 15) in the Atacama highlands (19°S) of northern Chile. At LRO, the fossil pollen record shows multi-centennial hydroclimatic anomalies during the last millennium, with wetter than present phases at 1155–1130, 865–670, and 215–80 cal yrs BP, and similar to present conditions between 1005 and 880 cal yrs BP. In contrast, the ISL record shows a wet phase during 1115–840 cal yrs BP, suggesting that meso-ecological processes were as important in vegetation turnover as regional hydroclimate anomalies. Wetter conditions derived from LRO partially overlap with the Medieval Climate Anomaly (865–670 cal yrs BP) and with the latest part of the Little Ice Age (215–80 cal yrs BP). Furthermore, no strong anthropogenic signal was identified possibly related to the remote location of the records. Palynological diversity analyses evidence increasing diversification of plant communities during wet events at both sites. In correlation to existing regional hydroclimatic records from the Western Andes, our precipitation reconstruction verifies that centennial-scale changes in the strength of the South American Summer Monsoon (SASM) and partial influence of El Niño-like (ENSO) conditions drove vegetation turnover in the Atacama Desert during the last millennium.

Investigations of how past human societies managed during times of major climate change can inform our understanding of potential human responses to ongoing environmental change. In this study, we evaluate the impact of environmental variation on human communities over the last four millennia in the southern Lake Titicaca basin of the Andes, known as Lake Winaymarka. Refined paleoenvironmental reconstructions from new diatom-based reconstructions of lake level together with archaeological evidence of animal and plant resource use from sites on the Taraco Peninsula, Bolivia, reveal frequent climate and lake-level changes within major cultural phases. We posit that climate fluctuations alone do not explain major past social and political transformations but instead that a highly dynamic environment contributed to the development of flexible and diverse subsistence practices by the communities in the Titicaca Basin.

Forecasting the effects of climate change on the distribution of Andean trees (Polylepis, Rosaceae) is important to understand how species respond to climate variability and to assess their resilience to the ongoing climate crisis. Here, paleodistribution modelling is used to assess distribution shifts of 17 Polylepis species during the Last Glacial Maximum (LGM), mid-Holocene (MH), and the Anthropocene in the central Andes. Species distribution models (SDMs) were computed by combining presence records and current climatic conditions using Maxent and projected onto three climatic scenarios for the LGM (~22,000 yr BP), the MH (~6,000 yr BP), and the Anthropocene (1,970–2,000). Subsequently, current refugia hotspots were identified by intersecting suitable habitat over the LGM, MH, and anthropogenic conditions for all the studied species. SDMs for the LGM and MH showed a contraction of climate suitable habitat for most of the species in comparison to the Anthropocene. Four current refugia hotspots were identified: central Cordillera of Peru, Lake Titicaca basin, western Cordillera of Bolivia, and northern Chile. In general, SDMs were consistent with patterns proposed with pollen records, and partially with available phylogeographic studies. Current hotspots are highly important areas for the conservation of Polylepis and associated biota. This study assists in understanding distribution shifts over millennia of Andean tree species in response to climate change and identifying key conservation areas for the delineation of future conservation strategies.

Anemophilous species depend on wind for sexual reproduction. When plants do not receive enough pollen and/or pollen has poor quality, they may experience pollen limitation. This can reduce the production of fruits and seeds with negative consequences on population dynamics. The self-compatibility system also plays an important role on the likelihood of a species suffering pollen limitation as it determines if plants can produce fruits and seeds in the absence of compatible mates. Here, we studied the breeding system of the Andean anemophilous tree Polylepis incarum, a critically endangered species endemic to Lake Titicaca. We conducted controlled experimental pollination experiments and florescence microscopy analysis to assess whether pollen limitation and the incompatibility system constrain fruit and seed production. Results showed that the seed set is limited by pollen availability, that P. incarum exhibits a pre-zygotic compatibility system and early inbreeding depression manifested during seed development. Therefore, self-pollination is a factor that could be partially associated with the production of non-viable seeds.

Significance Maize is a global food staple with great economic and cultural importance. Archaeogenomic studies have revealed a process of protracted maize domestication and multiple waves of human-mediated dispersal in the Americas. Maize first arrived in South America as a partial domesticate, where the domestication syndrome became independently fixed and improved varieties developed away from the influence of wild gene flow. We demonstrate that hybrids of some of these improved varieties were likely reintroduced back to Central America. We hypothesize that this backflow of South American genetic material may have contributed to the development of a more productive staple, which was related to the growth and aggregation of human populations, and the formation of more complex social and political structures regionally., Maize (Zea mays ssp. mays) domestication began in southwestern Mexico ∼9,000 calendar years before present (cal. BP) and humans dispersed this important grain to South America by at least 7,000 cal. BP as a partial domesticate. South America served as a secondary improvement center where the domestication syndrome became fixed and new lineages emerged in parallel with similar processes in Mesoamerica. Later, Indigenous cultivators carried a second major wave of maize southward from Mesoamerica, but it has been unclear until now whether the deeply divergent maize lineages underwent any subsequent gene flow between these regions. Here we report ancient maize genomes (2,300–1,900 cal. BP) from El Gigante rock shelter, Honduras, that are closely related to ancient and modern maize from South America. Our findings suggest that the second wave of maize brought into South America hybridized with long-established landraces from the first wave, and that some of the resulting newly admixed lineages were then reintroduced to Central America. Direct radiocarbon dates and cob morphological data from the rock shelter suggest that more productive maize varieties developed between 4,300 and 2,500 cal. BP. We hypothesize that the influx of maize from South America into Central America may have been an important source of genetic diversity as maize was becoming a staple grain in Central and Mesoamerica.

In vascular plants, larger seeds are generally associated with higher germination potential, healthier seedlings and overall higher rates of survivorship. How this relationship holds or what other physiological tradeoffs evolved in plants adapted to high-altitude environments, such as the tropical and subtropical highland Polylepis tree, remain unclear. In this study, we evaluated the relationship between seed mass and seedling performance by testing the reserve effect, the metabolic effect, and the seedling-size effect hypotheses in Polylepis tomentella Weddell (Rosaceae). Since the relationship between fitness and seed size can often depend on maternal plant size, we additionally investigated the association between germination success, seedling performance (survival, relative growth rate (RGR) and height), and size of bearing-seed trees under controlled greenhouse conditions. Our results showed that heavier seeds are more likely to germinate, but we did not find evidence that could support the reserve effect, metabolic effect or seedling-size effect. As seedlings from larger and medium seeds exhibited comparatively similar RGR, survival percentages and final size, maternal plant size was positively associated with improved seed quality and seedling performance. These results demonstrate that seed mass and maternal size during early seedling establishment are critical for Polylepis persistence, demography and conservation.

Polylepis tarapacana forms one of the highest-altitude woodlands worldwide. Its populations are experiencing a decline due to unsustainable land-use practices, climate change, and fungal infection. In Sajama National Park in Bolivia, Polylepis tarapacana is affected by a disease caused by the pleosporalean fungus Leptosphaeria polylepidis, recently described in 2005. In this study, the integrative morphological and molecular analyses using sequences from multiple DNA loci showed that it belongs to the genus Paraleptosphaeria (Leptosphaeriaceae, Pleosporales). Accordingly, the appropriate new combination, Paraleptosphaeria polylepidis, is made. Pseudothecia of Pa. polylepidis were found to be overgrown by enigmatic conidiomata that were not reported in the original description of this fungus. Morphological and molecular analyses using sequences from two DNA loci revealed that they belong to an undescribed genus and species in the family Dictyosporiaceae (Pleosporales). The new generic and specific names, Sajamaea and S. mycophila, are introduced for this unusual fungus.

Resumen ∙ Los bosques de Polylepis pacensis son endémicos de Bolivia y se distribuyen en los departamentos de La Paz (inmediaciones al nevado Illimani, Quime e Inquisivi) y Cochabamba (Cotacajes). En este estudio, se evaluó el ensamble de aves en cuatro fragmentos de bosque de P. pacensis ubicados en las faldas del nevado Illimani, La Paz, Bolivia. En estos fragmentos de bosque se observaron 31 especies de aves, incluyendo dos especies endémicas de Bolivia, Colibrí Negrito (Aglaeactis pamela) y Pinchaflor Carbonero (Diglossa carbonaria), y dos especies fuertemente especializadas a bosques de Polylepis, Tijeral de Yánac (Leptasthenura yanacensis) y Conirrostro Gigante (Conirostrum binghami). Los bosques de Polylepis pacensis están altamente amenazados por actividades humanas como quema, extracción de leña y agricultura; las cuales podrían estar causando la deforestación y degradación de este importante hábitat para las aves. Es crucial implementar programas de conservación que incluyan la participación activa de la población local.Abstract ∙ Bird assemblages in endemic Polylepis pacensis woodlands in Bolivia Polylepis pacensis woodlands are endemic to Bolivia, distributed in La Paz (near Illimani, Quime, and Inquisivi) and Cochabamba (Cotacajes) departments. In this study, we evaluated the bird assemblages of four fragments of P. pacensis woodlands located in the foothills of nevado Illimani, La Paz, Bolivia. In these woodlands, we recorded 31 bird species, including two endemic species of Bolivia, Black-hooded Sunbeam (Aglaeactis pamela) and Grey-bellied Flowerpiercer (Diglossa carbonaria), and two species strongly specialized to Polylepis woodlands, Tawny Tit-spinetail (Leptasthenura yanacensis) and Giant Conebill (Conirostrum binghami). Polylepis pacensis woodlands are highly threatened by human activities, such as burning, logging and agriculture; which may be causing of deforestation and degradation of this important habitat for bird species. It is crucial to implement conservation programs involving the active participation of local people.

En el presente estudio se evaluó la fenología de la queñua (Polylepis incarum, Rosaceae) durante un ciclo anual en la puna mesofítica de La Paz, Bolivia. Esta especie es endémica de la cuenca del Lago Titicaca y, al igual que otras especies del género, P. incarum está categorizada como En Peligro para Bolivia debido a actividades antrópicas como la extracción de leña y la expansión de cultivos. Durante un año (marzo 2015 - febrero 2016) se realizaron evaluaciones mensuales en un parche de bosque en la comunidad de Kopacati, departamento de La Paz, Bolivia. Los objetivos del estudio fueron identificar las épocas de floración y fructificación, y relacionar el éxito reproductivo con el tamaño de la planta y con factores ambientales. P. incarum produce botones florales entre julio y agosto. La producción de flores en estado femenino se produce entre julio y noviembre, y la de flores en estado masculino, entre julio y octubre. La mayor producción de frutos inmaduros ocurrió a partir de noviembre; los frutos alcanzaron la madurez entre de diciembre y enero. Tanto la precipitación como la temperatura mostraron una influencia significativa en la producción de flores y frutos. El diámetro a la altura del pecho (DAP) fue el único carácter alométrico que influyó de manera significativa en la producción de flores y de frutos. No se detectaron diferencias significativas en la producción de flores y frutos entre árboles y arbustos. Los patrones fenológicos informados para esta especie son similares a los reportados para P. tomentella y P. besseri. Los resultados de este trabajo contribuyen al conocimiento de la biología reproductiva de Polylepis incarum y a la promoción de programas de conservación y reforestación de la especie. In this study, the phenology of queñua (Polylepis incarum, Rosaceae) was evaluated during an annual cycle in the mesophytic puna of La Paz. The species is endemic to the Lake Titicaca basin. Like other species of the genus Polylepis, P. incarum is categorized as Endangered for Bolivia due to anthropic activities as firewood extraction and crop expansion. During one year (March 2015 - February 2016), we conducted monthly evaluations in a woodland located in the community of Kopacati, Copacabana department, La Paz, Bolivia. The objectives of the study were to identify flowering and fruiting times, and to assess the relationships between plant size, environmental factors and plant reproductive success. The species produces floral buds between July and August. The production of flowers in the female state occurs between July and November, and flowers in the male state, between July and October. The highest production of immature fruits took place in November, reaching maturity in December and January. Both precipitation and temperature showed a significant influence on flowers and fruits production. Diameter at breast height (DBH) was the only allometric character significantly associated to the production of flowers and fruits between trees and shrubs. There was no significant difference in the production of flowers and fruits between trees and shrubs. The phenological patterns informed for this species are similar those reported for P. tomentella and P. besseri. The results of the present study contribute to the knowledge about the reproductive biology of Polylepis incarum and to promote programs of conservation and reforestation of the species.

Según los diversos tratamientos taxonómicos, el número de especies del género Polylepis oscila entre 33 y 28 especies. Sin embargo, hasta el momento no se pudieron delimitar claramente las especies de este género. Es difícil definir sus orígenes evolutivos y conocer los procesos de especiación. Esta complejidad obedecería a distintos procesos que actúan de forma independiente y sinérgica dependiendo del grupo de especies: diferenciación relativamente reciente, poliploidía, hibridación y el aparente rol del ser humano en su distribución. En este artículo realizamos una revisión de la situación taxonómica actual del género Polylepis. Proponemos 28 especies e incluimos 2 nuevas especies descriptas para Perú y una especie (P. tomentella) con tres subespecies. Además, discutimos los vacíos en el conocimiento y proponemos estrategias de investigación que permitan mejorar la delimitación de las especies. A fin de proveer una estructura taxonómica dentro de los estudios y para que los datos obtenidos constituyan un aporte a los procesos de conservación de estos bosques, taxónomos y conservacionistas debemos trabajar en conjunto para delimitar las unidades de conservación que eviten ambigüedades y para, de esta manera, definir estrategias claras. The number of species in the genus Polylepis has changed, according to the systematic treatments, from 33 to 28; however, until now there is not a clear species delimitation. It has been complicated to define evolutionary origins and understand speciation. This complexity may be the result of different processes acting independently or interacting: recent radiation, poliploidy, hibridization and the human intervention in its distribution, depending of the species group. In this article, we revised the taxonomic status of the genus Polylepis. Twenty-eight species are proposed, with the inclusion of two new species for Perú and one species (P. tomentella) with three subespecies. In addition, gaps of knowledge are analyzed and strategies of research are proposed to improve species delimitation. Incorporating a taxonomic structure could generate new insights to conservation, restoration and management projects; taxonomists and conservationist need to work together to define conservation units to avoid ambiguities and define new strategies.

Premise of research. Anemophily is considered to be a mechanism that evolved to promote pollination success. However, reproductive output can decrease if pollen loads are scarce due to low abundance of compatible mates or floral infections. Here we analyze the effects of breeding system, pollen limitation, and a potential floral fungal infection on the reproductive output of the Andean tree Polylepis tomentella (Rosaceae).Methodology. We performed pollen supplementation experiments in the field to assess the extent of the effect of pollen limitation on fruit and seed set and to identify any pre- or postzygotic self-incompatibility responses within receptive pistils. Supplementary scanning electron microscopy and epifluorescence microscopy were used to observe the possible effects of a potential floral fungal infection on sexual reproduction.Pivotal results. Pollen supplementation did not increase fruit and seed set, suggesting weak evidence of pollen limitation. Most stigmas from self- and cross-pollinate...

Los bosques de Polylepis (Rosaceae) constituyen hábitats importantes para la flora y fauna altoandina y proveen servicios ecosistémicos directos a las comunidades indígenas. Sin embargo, existen pocos relevamientos florísticos así como estudios etnobotánicos en estos ecosistemas boscosos. Evaluamos la composición florística, los usos socioeconómicos de las especies y la valoración local sobre los bosques de P. pacensis y P. incarum en los Andes occidentales bolivianos. Registramos un total de 46 especies de plantas en los bosques de P. pacensis y 58 especies en los bosques de P. incarum. Cada uno incluye dos especies endémicas, respectivamente, Aa trilobulata y Calceolaria bartsiifolia, e Hieracium padcayense y Calceolaria bartsiifolia. En total 13 especies medicinales son utilizadas para tratar una variedad de enfermedades. Las comunidades indígenas locales utilizan Polylepis como combustible, medicina, material de construcción y poseen un importante valor ritual. El 54% de los entrevistados mencionaron que la cobertura de P. pacensis se mantuvo durante los últimos 10 años; mientras que el 44% de los entrevistados consideró que los bosques de P. incarum aumentaron y el 40% consideró que éstos disminuyeron. Se precisan programas de conservación que involucren la participación activa de las comunidades indígenas locales, para mejorar la valoración de estos ecosistemas boscosos. Polylepis forests constitute important habitats for an array of Andean fauna and flora and provide direct ecosystem services to local indigenous communities. However, there are very few floristic surveys as well as ethnobotanic studies in these forest ecosystems. In this study, we evaluated the floristic composition of these forests, the socio-economic use of plant species, and the local assessment of past cover of P. pacensis and P. incarum forests in the western Bolivian Andes. We recorded a total of 46 plant species in P. pacensis forests and 58 species in P. incarum forests. They each include two endemic species, respectively, Aa trilobulata and Calceolaria bartsiifolia, and Hieracium padcayense and Calceolaria bartsiifolia. At least 13 species are medicinal and used to treat a variety of illnesses. Local indigenous communities use Polylepis as fuel, medicine, wood, and building material and it possesses an important ritual value. Fifty four percent of the interviewers considered that P. pacensis cover stayed unchanged for the last 10 years; whereas 44% perceived that P. incarum cover has increased, and 40% considered that it has decreased over the last 10 years. Conservation programs need to include the active participation of local indigenous communities, in order to improve the local valorization of these forest ecosystems.

The high Andes of South America were among the last environments that Homo sapiens colonized during its Pleistocene dispersion out of Africa. The peopling of this high-elevation environment was constrained by atmospheric hypoxia, cold stress, and resource availability. Here we report archaeological and geoarchaeological analyses from Cueva Bautista, a dry rock shelter, located at 3933 m above sea level in southwestern Bolivia. We focus on a well-preserved occupation surface containing hearths and high-quality stone tools AMS dated to 12,700–12,100 cal BP. Geoarchaeological resolution of the site supports its stratigraphic integrity and archaeological analyses indicate that the early human occupation was formed as a temporary camp by mobile foragers relying on a curated technological strategy. Regional paleoenvironmental reconstructions suggest that Cueva Bautista's occupation was synchronous with humid conditions and its abandonment with increased aridity. Our findings suggest that mobile hunter-gatherers explored – albeit not colonized – the high Andes during the late Pleistocene and provides further support that a combination of biological, behavioral, and environmental constraints affected human adaptation to this extreme environment.

Fil: Cuyckens, Griet An Erica. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Centro de Estudios Ambientales Territoriales y Sociales; Argentina

Andean wetlands or bofedales are commonly used by indigenous communities for livestock production. Decisions regarding management of bofedales involve the active participation of local people and their social institutions. Consequently, any action addressing emerging challenges must be implemented in coordination and agreement with local actors. This decision process requires an understanding of the local socioeconomic and cultural dynamics, especially those related to land and natural resource management. In many Andean communities, the ayllu is the institution that governs decisions on regional land use. However, in the face of increasing challenges such as climate change and population growth, use of the ayllu has declined in favor of individual decision-making. Here we discuss how the Andean camelid herders of Sajama National Park in highland Bolivia rely on both the ayllu and family-level decision-making to manage their pastoralist landscapes, including their bofedales. Using a rights mappin...

The Lake Titicaca Basin is one of the regions in the world where both primary village and state formation occurred in prehistory. Although agriculture has been discussed as the central engine fueling these processes, fish and other aquatic resources were significant but little-understood components of the region's ancient economy. In this paper, we use zooarchaeological analysis of faunal remains from 367 flotation samples recovered from five archaeological sites to discuss the interplay between fishing, environmental change, and the emergence of sociopolitical complexity in the Taraco Peninsula of Lake Titicaca. Our results suggest that fishing comprised a significant component of the local inhabitants' diet between 1500 BC and 1100 AD. The intensity of fish procurement, however, varied through time and independently of both climatic and population change. We interpret variation in fish consumption through time as a product of group and individual decisions to optimize resource use in a context of dynamic environmental and sociopolitical variability. © 2014 Elsevier Inc.

The European conquest of the New World produced major socio-environmental reorganization in the Americas, but for many specific regions and ecosystems, we still do not understand how these changes occurred within a broader temporal framework. In this paper, we reconstruct the long-term environmental and vegetation changes experienced by high-altitude wetlands of the southcentral Andes over the last two millennia. Pollen and charcoal analyses of a 5.5-m-long core recovered from the semi-arid puna of northern Chile indicate that while climatic drivers influenced vegetation turnaround, human land use and management strategies significantly affected long-term changes. Our results indicate that the puna vegetation mostly dominated by grasslands and some peatland taxa stabilized during the late Holocene, xerophytic shrubs expanded during extremely dry events, and peatland vegetation persisted in relation to landscape-scale management strategies by Andean pastoralist societies. Environmental changes produced during the post-conquest period included the introduction of exotic taxa, such as clovers, associated with the translocation of exotic herding animals (sheep, cattle, and donkeys) and a deterioration in the management of highland wetlands.

In the Andean highlands, Polylepis woodlands are a rare and unique ecosystem of the treeline. Although human activities have caused the loss of extensive forested areas and decreased woodland regeneration, few systematic and quantitative assessments have been carried out in Polylepis forests. This study compares differences in habitat characteristics, population structure, and reproductive output in populations of Polylepis tomentella subject to different levels of human disturbance in the south-central Andes of Bolivia. We selected P. tomentella because the species still covers large extensions in the form of fragmented forest patches. Results show that human activities affected all the studied populations. Moderately disturbed populations exhibited a lower percentage of farmed area (0.6%) and browsed plants (4%) than strongly disturbed populations (5% and 12%, respectively). All populations exhibited similar proportion of plants with logging scars. Potassium content and canopy closure were 1.5 and 2.5 higher, respectively, in strongly disturbed populations. The density of saplings and seedlings were 75 percent and 80 percent lower in strongly disturbed populations than in moderately disturbed population, even though reproductive individuals produced twice more flowers and fruits. Our results suggest that fruit production does not limit regeneration of P. tomentella and post-dispersal mechanisms may decrease seed germination and increase seedling mortality. Overall, strongly disturbed populations will be less likely to regenerate, leading to population decline. Conservation programs should facilitate forest recovery by promoting seedling establishment, reducing overharvesting and over-browsing, and protecting remaining adult plants.

Increasing elevation can restrict the expansion of tree species by negatively affecting growth. In this study, we estimated growth velocity and evaluated the effects of extreme elevation on radial growth of the Andean tree Polylepis tarapacana Philippi (Rosaceae). We also developed different models to predict the relationship between age (number of tree-rings) and allometric characters (total height and diameter). Samples of trees and shrubs were collected between 4,200 and 4,600 m asl and analyzed using standard dendrochronological methods. Results evidenced that P. tarapacana is a slow-growing species since it grows less than 5 mm per year. Furthermore, elevation has a negative effect on radial growth. Morphometric models showed that a positive relationship between total height and diameter exists but not a significant relation between number of tree-rings and morphometry. Elevation had a major role in the radial growth of P. tarapacana which interacts with microclimatic conditions. Careful considerations should be made at the moment of using allometry as a surrogate for age in ecological studies.

This paper presents a detailed zooarchaeological study of fish remains from the site of Kala Uyuni, Bolivia. The fish remains of 31 flotation samples from different archaeological contexts and dated to the Formative Period (1000 BC–AD 400) are described in terms of frequency, weight, taxa distribution, sizes, skeletal representations, and exposure to heat. The results confirm the importance of fish in the diet of the inhabitants of the site and provide insights about the particularities of their exploitation, consumption, and differential discard across the site throughout time. A strong decline in the procurement and consumption of fish is observed for the Late Formative which seems to be a consequence of both environmental and social processes.