SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Aconcagua

55

High-elevation environments above 2500 metres above sea level (m.a.s.l.) were among the planet’s last frontiers of human colonization. Research on the speed and tempo of this colonization process is active and holds implications for understanding rates of genetic, physiological and cultural adaptation in our species. Permanent occupation of high-elevation environments in the Andes Mountains of South America tentatively began with hunter-gatherers around 9 ka according to current archaeological estimates, though the timing is currently debated. Recent observations on the archaeological site of Soro Mik'aya Patjxa (8.0-6.5 ka), located at 3800 m.a.s.l. in the Andean Altiplano, offer an opportunity to independently test hypotheses for early permanent use of the region. This study observes low oxygen (δ(18)O) and high carbon (δ(13)C) isotope values in human bone, long travel distances to low-elevation zones, variable age and sex structure in the human population and an absence of non-local lithic materials. These independent lines of evidence converge to support a model of permanent occupation of high elevations and refute logistical and seasonal use models. The results constitute the strongest empirical support to date for permanent human occupation of the Andean highlands by hunter-gatherers before 7 ka.

Concepts: Scientific method, South America, Bolivia, Andes, Peru, Altiplano, Lake Titicaca, Aconcagua

2

General patterns of forest dynamics and productivity in the Andes Mountains are poorly characterized. Here we present the first large-scale study of Andean forest dynamics using a set of 63 permanent forest plots assembled over the past two decades. In the North-Central Andes tree turnover (mortality and recruitment) and tree growth declined with increasing elevation and decreasing temperature. In addition, basal area increased in Lower Montane Moist Forests but did not change in Higher Montane Humid Forests. However, at higher elevations the lack of net basal area change and excess of mortality over recruitment suggests negative environmental impacts. In North-Western Argentina, forest dynamics appear to be influenced by land use history in addition to environmental variation. Taken together, our results indicate that combinations of abiotic and biotic factors that vary across elevation gradients are important determinants of tree turnover and productivity in the Andes. More extensive and longer-term monitoring and analyses of forest dynamics in permanent plots will be necessary to understand how demographic processes and woody biomass are responding to changing environmental conditions along elevation gradients through this century.

Concepts: Argentina, Andes, Aconcagua

0

In the highlands of the Andes, lizards must balance precisely the allocation of energy for growth and reproduction to ensure their survival. We studied the individuals' age, growth rates, age at sexual maturity, and maximum life span of the viviparous lizard Phymaturus antofagastensis, endemic of cold and harsh environments at high altitudes in the Andes Mountains of Catamarca province, Argentina. We also estimated key life history parameters like reproductive effort, lifetime reproductive effort, net reproductive rate, and relative reproductive time in P. antofagastensis as well as in other Phymaturus to compare the interplay among growth, maintenance, and reproduction in species that live across a latitudinal and altitudinal gradient. We found that females and males of P. antofagastensis mature late in life, at 6-7 years old, respectively, and some individuals reached 20 years of age. Adult females showed higher specific growth rates than males and an adult life span of 9 years which, due to their biennial reproduction, results in an estimated production of only four litters in life. This species exhibits one of the highest lifetime reproductive efforts described for lizards. Our results indicate the existence of a tradeoff between the number of reproductive events throughout life and reproductive effort devoted to each event in Phymaturus, related to the phylogenetic group. The palluma group shows low reproductive effort but high number of reproductive events throughout their lives, whereas the patagonicus group shows high reproductive efforts in low number of reproductive events.

Concepts: Human, Male, Reproduction, Female, Argentina, Andes, Aconcagua

0

0

The aim of this work was to achieve a preliminary characterization of the profile of the phenolic fraction of virgin olive oils (VOOs) from Maipú (Mendoza, Argentina). Thus, 25 commercial VOO samples from Arauco, Arbequina, Picual, Frantoio, Changlot, Empeltre, Nevadillo, Manzanilla and Coratina (both monovarietals and blends) were analyzed using LC-ESI-QTOF MS and LC-ESI-IT MS for identification and quantification purposes, respectively. A rapid LC method (15 min) accomplished quantitative information about a total of 40 phenolic compounds, including secoiridoid derivatives, which have not been evaluated before in samples coming from the sub-region so-called Maipú (Mendoza province, Argentina). The results make evident that olive oils coming from Mendoza can be considered as important sources of phenolic bioactive compounds, exhibiting similar phenolic compounds levels to those shown by oils from other typical world production regions. Moreover, some distinctive features of Arauco variety (Argentinean autochthonous variety) were pointed out; indeed, a correlation between flavonoids content and botanical variety was established herewith.

Concepts: Olive, Argentina, Olive oil, Provinces of Argentina, Aconcagua, Argentine wine, Mendoza, Argentina, Mendoza River

0

The goal of this article is to assess the scale of human paleomobility and ecological complementarity between the lowlands and highlands in the southern Andes during the last 2,300 years. By providing isotope results for human bone and teeth samples, we assess a hypothesis of “high residential mobility” suggested on the basis of oxygen isotopes from human remains.

Concepts: Chemical element, Bolivia, Argentina, Chile, Andes, Presidential system, Aconcagua

0

At two trench segments below the Andes, the Nazca Plate is subducting sub-horizontally over ∼200-300 km, thought to result from a combination of buoyant oceanic-plateau subduction and hydrodynamic mantle-wedge suction. Whether the actual conditions for both processes to work in concert existed is uncertain. Here we infer from a tectonic reconstruction of the Andes constructed in a mantle reference frame that the Nazca slab has retreated at ∼2 cm per year since ∼50 Ma. In the flat slab portions, no rollback has occurred since their formation at ∼12 Ma, generating ‘horse-shoe’ slab geometries. We propose that, in concert with other drivers, an overpressured sub-slab mantle supporting the weight of the slab in an advancing upper plate-motion setting can locally impede rollback and maintain flat slabs until slab tearing releases the overpressure. Tear subduction re-establishes a continuous slab and allows the process to recur, providing a mechanism for the transient character of flat slabs.

Concepts: Earth, Plate tectonics, South America, Andes, Peru, Quechua, Nazca Plate, Aconcagua

0

On the basis of morphological studies of a collection sample from the southern Andes of Argentina and Chile, we describe and name two new species of Stigmella Schrank (Lepidoptera: Nepticulidae): S. sinuosa Remeikis & Stonis, sp. nov. and S. mevia Remeikis & Stonis, sp. nov. Other two new species are documented but left unnamed. All treated taxa belong to a newly designated S. sinuosa complex that belongs to the S. salicis group. The S. sinuosa complex contains cryptic species. We also discuss the differentiation of the species of the complex by using morphological characters.

Concepts: Species, Bolivia, Argentina, Chile, Andes, Patagonia, Aconcagua

0

Nature-based tourism and recreation activities have a range of environmental impacts, but most protected area agencies have limited capacity to assess them. To prioritise where and what impacts to monitor and manage, we conducted a desktop assessment using Geographical Information Systems (GIS) by combining recreation ecology research with data on visitor usage and key environmental features for a popular protected area used for mountaineering and trekking, Aconcagua Provincial Park (2400-6962 m a.s.l.) in the Andes of Argentina. First, we integrated visitor data from permits with environmental data using GIS. We then identified key impact indicators for different activities based on the recreation ecology literature. Finally, we integrated this data to identify likely ecological impacts based on the types of activities, amount of use and altitudinal zones. Visitors only used 2% of the Park, but use was concentrated in areas of high conservation value including in alpine meadows and glacier lakes. Impacts on water resources were likely to be concentrated in campsites from the intermediate to the nival/glacial zones of the Park while impacts on terrestrial biodiversity were likely to be more severe in the low and intermediate alpine zones (2400-3800 m a.s.l.). These results highlight how visitor data can be used to identify priority areas for on-ground assessment of impacts in key locations. Improvements to the management of visitors in this Park involves more effective ways of dealing with water extraction and human waste in high altitude campsites and the impacts of hikers and pack animals in the low and intermediate alpine zones.

Concepts: Ecology, Geographic information system, South America, Argentina, Andes, Mountaineering, Aconcagua, Provincial park

0

A new species of Chaco Tullgren, 1905 is described and illustrated from the Andean foothills of Mendoza province, western Argentina. This is the tenth species of the genus and the first record of Chaco in Mendoza. An updated key is presented for all Chaco species. The cladistic analysis based on a previously published morphological character matrix resulted in the consensus tree: (C. obscura, C. tucumana, C. castanea, (C. socos + C. tigre) (C. tecka (C. sanjuanina (C. Patagonia + C. ansilta sp. nov.)))).

Concepts: Family, Order, Argentina, Kingdom, Andes, Provinces of Argentina, Aconcagua, Mendoza Province