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In this paper, we argue for the inclusion of archaeology in discussions about how humans have contributed to and dealt with climate change, especially in the long term. We suggest Niche Construction Theory as a suitable framework to that end. In order to take into account both human and environmental variability, we also advocate for a situated perspective that includes the Global South as a source of knowledge production, and the Neotropics as a relevant case study to consider. To illustrate this, we review the mid-Holocene Hypsithermal period in the southern Puna and continental Patagonia, both in southern South America, by assessing the challenges posed by this climate period and the archaeological signatures of the time from a Niche Construction Theory perspective. Finally, we emphasize the importance of these considerations for policymaking. This article is part of the theme issue 'Climate change adaptation needs a science of culture'. [ABSTRACT FROM AUTHOR]

Understanding the use of natural corridors is critical for characterizing the past use of marginally occupied landscapes at the Andean fringes of western Patagonia by the hunter-gatherer groups who inhabited this region. In this paper, we combine least-cost path models and archaeological surveys and excavations to determine the possible movements along the southern margin of General Carrera Lake. The methodology includes defining uncertainties that allow for modeling a set of equiprobable routes, thereby avoiding problems with errors and biases from predictors, such as slope, land-use cover, and seasonality. The results identify mobility corridor bottlenecks, i.e., geographical areas with a high probability of travel routes with equiprobable routes that converge. In addition, we identify areas where travel routes are likely to diverge into multiple semi-parallel routes. The study of archaeological sites provides stratigraphic data to control for the chronology and characteristics of mobility along this transect. The correlation between archaeological sites and paths, specifically for the control and winter scenarios, shows the quality of these route predictions. These results indicate the repeated use of internodal spaces that were effectively incorporated into mobility during the last three millennia. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Estudios Sociales is the property of Universidad de los Andes and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The carabid beetle Cnemalobus Guérin-Ménéville, 1838 inhabits high- and lowland grasslands of southern South America. The highest diversity is found in the Patagonian Steppe, where distribution patterns are associated with latitude and elevation. Northern Patagonia, a large volcanic region with a complex geoclimatic history, exhibits elevated grades of endemism. However, a great deal remains unknown regarding diversification and biogeographical patterns for most of the endemic groups. We describe new Cnemalobus species restricted to isolated volcanoes from these extra-Andean mountain systems. We assess the phylogenetic relationships by updating the phylogeny of the genus and conduct a Bayesian binary Markov chain-Monte Carlo (MCMC) analysis on the resulting phylogenetic tree to discuss the biogeographical distribution patterns. We also provide a taxonomic key to all currently known species of Cnemalobus from the Patagonian Steppe. Our phylogenetic analysis supports the monophyly of the new species Cnemalobus tromen sp. nov., Cnemalobus silviae sp. nov., Cnemalobus aucamahuida sp. nov. and Cnemalobus domuyo sp. nov. grouped with C. diamante and C. nevado, referred to as the 'Extra-Andean' mountain lineage. Biogeographical analysis recognises vicariant events as the most plausible explanation for the allopatric distributions of the new species. We hypothesise that these vicariant events could be related to climatic barriers that likely promoted speciation processes by generating geographical isolation in ancestral populations. Our findings contribute significantly to the biogeographical understanding of the Patagonian volcanic region, prompting new inquiries to unravel the speciation processes of the endemic biota in extra-Andean mountain systems. [ABSTRACT FROM AUTHOR]

The abundance of southern right whales (Eubalaena australis) was estimated by the means of aerial line-transect surveys for the area of Bahía San Antonio, a bay located in the north-western region of the San Matías Gulf (40°50'S 64°50'W), Rio Negro, Patagonia Argentina. In total, seven aerial surveys were conducted in the first week of August and September 2009, September, October and November 2010, and August, September 2011. Survey effort equalled a total flight time of 12.4h, during which 200 whales were counted in 119 whale groups. Half of the encounters were solitary animals and 17% were mating groups. Corrected abundance estimates showed the highest amount of whales present in the bay during the month of September, with 85±71, 207±108 and 117±55 animals in 2009, 2010 and 2011 respectively. In adjacent months, less than half the amount of whales seemed to be present. The correction factor g(0)availability resulted 0.392±0.456. Perception bias was not accounted for. These aerial surveys resulted in the first estimates of southern right whale abundance in this north Patagonian bay and indicated a rather abrupt peak during the month of September. This being the peak month for right whale presence is consistent with data from other regions in the Southwest Atlantic, but data obtained in the other months remained scarce and thus results should be interpreted carefully. The complete absence of whales in the area during November 2010 and August 2011 raises further questions on the predictability of the whale's presence in the area. Overall, more consistent aerial surveys should be conducted to accurately determine the annual and interannual evolution of southern right whale abundance in the study area. [ABSTRACT FROM AUTHOR]

Copyright of Cuadernos de Investigación Geográfica is the property of Universidad de la Rioja, Servicio de Publicaciones and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Theria represent an extant clade that comprises placental and marsupial mammals. Here we report on the discovery of a new Late Cretaceous mammal from southern Patagonia, Patagomaia chainko gen. et sp. nov., represented by hindlimb and pelvic elements with unambiguous therian features. We estimate Patagomaia chainko attained a body mass of 14 kg, which is considerably greater than the 5 kg maximum body mass of coeval Laurasian therians. This new discovery demonstrates that Gondwanan therian mammals acquired large body size by the Late Cretaceous, preceding their Laurasian relatives, which remained small-bodied until the beginning of the Cenozoic. Patagomaia supports the view that the Southern Hemisphere was a cradle for the evolution of modern mammalian clades, alongside non-therian extinct groups such as meridiolestidans, gondwanatherians and monotremes. [ABSTRACT FROM AUTHOR]

On the southwestern margin of the North Patagonian Massif (Argentina), there is a NW–SE trending belt consisting of igneous and metamorphic rocks that is named the Central Patagonian Igneous Metamorphic Belt. It defines the boundary between the mentioned massif and southern Patagonia (including the Deseado Massif). It is debatable whether this belt belongs to an orogen generated by accretion or collision and whether it was created in a single event or over the course of several events. Paleogeographic reconstructions were conducted to answer this query, confirming that there are tectonic processes involved in two events: the Chanic (Devonian) and the Gondwanan (late Carboniferous–early Permian) events. They show a movement of South America toward the SW during which an accretionary orogen was built during the Chanic event between ca. 400 Ma and ca. 360 Ma. Later, the paleogeographic reconstructions show an abrupt change in the movement of South America; it is proposed that due to this movement, the previously built orogen collapsed between ca. 360 Ma and ca. 330 Ma. During the Gondwanan event, the subduction surrounding Pangea in the Patagonian belt caused plutonic emplacement in the already-existing orogen structures and paleogeographic reconstructions depict South America with a movement toward the northeast, which involves a displacement due to a slab pull from the northern Paleotethys Ocean boundary. It is further supported that lateral displacement between Gondwana domains brought forth by this slab pull is what led to the assembly between the North Patagonian Massif and southern Patagonia. [ABSTRACT FROM AUTHOR]

This paper reports on sightings and dispersion of individual southern elephant seals (Mirounga leonina) along the Atlantic and Pacific coasts of South America based on reports of tagged/marked seals from Patagonia and of animals of unknown origin. From 154 sightings, encompassing at least 354 individuals, we found that individuals dispersed to subequatorial latitudes on both sides of the continent, and to more temperate sites, in the Magellanic region of Tierra del Fuego. Nineteen sites were visited by tagged seals from the established colony of Peninsula Valdés (PV, Argentina). PV and the smaller seal population of the Falklands/Malvinas were regularly connected by adults of both sexes. There were more sightings of males than females. No incipient new breeding colonies were found along the Atlantic coast of South America. Some observations coincided with places where elephant seals had been recorded or exploited in the seventeenth and eighteenth centuries. A shortage of suitable habitat for expansion and proximity to predictable food could act as a stabilizing process preventing colonization of new areas from PV. Dispersion data, coherent with population genetics, support a Patagonian elephant seal stock. [ABSTRACT FROM AUTHOR]

Simple Summary: Natural pearls of Diplodon chilensis, a freshwater clam native to southern South America, are reported and characterized for the first time. The finding also constitutes the first record of pearls in a species of the genus Diplodon. The pearls have different shapes and sizes, and were found in both, male and female specimens. The microstructure and chemical composition of pearls is consistent with those reported in other bivalve species. The capability to produce pearls is widespread in the phylum Mollusca, including bivalves of the superfamily Unionoidea. Here, we identified and characterized natural pearls formed by Diplodon chilensis, a freshwater clam native to southern South America, using samples obtained from two lakes located in the Chilean Patagonia. Pearls were studied using light and scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. Naturally formed pearls were found in both male and female D. chilensis specimens. Pearls are produced in different shapes, including spherical, ellipsoidal, buttoned, and bumpy, ranging in size from 200 µm to 1.9 mm. The internal microstructure is composed of irregular polygonal tablets, about 0.40 to 0.55 μm in thickness. EDX analysis showed that pearls are composed of calcium carbonate. FTIR and Raman spectra recorded several peaks attributable to the aragonite in pearls of this species, as has been shown in other mollusks. In addition to these results, pearls of different colors are illustrated. [ABSTRACT FROM AUTHOR]

We applied a step-down factor analysis (SDFA) and multi-site generalised dissimilarity modelling (MS-GDM) to local flea communities harboured by small mammals (i.e., collected at small sampling sites over a short time period) in two South American regions (Patagonia and the Northwestern Argentina) with the aim of understanding whether these communities were assembled via niche-based or dispersal-based processes. The SDFA allows us to determine whether clusters of flea assemblages across different types of climates, vegetation and soils can be distinguished (suggesting niche-based assembly). MS-GDM allows us to determine whether a substantial proportion of the variation in flea species turnover is explained by specific climate-associated, vegetation-associated and soil-associated variables (indicating niche-based assembly) or host turnover (indicating dispersal-based assembly). Mapping of assemblages on climate, vegetation and soil maps, according to their loadings on axis 1 or axis 2 of the SDFA, did not provide clear-cut results. Clusters of similar loadings could be recognized within some, but not other, climate, vegetation and soil types. However, MS-GDM demonstrated that the effect of environmental variables (especially air temperature) on flea compositional turnover was much stronger than that of host turnover, indicating the predominance of niche-based processes in local community assembly. A comparison of our results with those on the mechanisms that drive species assembly in regional communities allows us to conclude that local and regional communities result from the joint action of niche-based and dispersal-based processes, with the former more important at a smaller spatial scale and the latter at a larger spatial scale. [ABSTRACT FROM AUTHOR]

Background: Deer species play an important role in the enzootic cycles of several Anaplasma species. While in the Northern Hemisphere ticks of genus Ixodes are well recognized vectors of these intracellular bacteria, less is known regarding the biological cycles of Anaplasma spp. in South America. Methods: Using PCR protocols and Sanger sequencing, we assessed the presence of Anaplasma spp. in blood and ticks collected on a native deer species (Pudupuda) from southern Chile. Results: Based on phylogenetic analyses of the 16S rRNA, gltA and groEL genes and calculation of average sequence divergence for groEL, our results bring to light a novel genovariant of Anaplasmaphagocytophilum (named strain "Patagonia"). The strain represents a novel ecotype within the A. phagocytophilum species complex and was detected in both P.puda and their ticks. Using a larger matrix, denser taxon sampling and outgroup, our maximum-likelihood- and Bayesian-inferred phylogenies for groEL provide an accurate picture of the topology of A. phagocytophilum ecotypes and their evolutionary relationships. Conclusions: This is the first report of an ecotype of A. phagocytophilum in South America. Our results provide novel insight into the genetic diversity and ecology of this complex of bacterial lineages. Further studies should elucidate the enzootic cycle of A. phagocytophilum strain "Patagonia" and assess its pathogenic potential for pudues, domestic animals and humans in the region. [ABSTRACT FROM AUTHOR]

To understand the main orographic and non‐orographic sources of gravity waves (GWs) over South America during an Experiment (Rapp et al., 2021, https://doi.org/10.1175/BAMS-D-20-0034.1), we propose the application of a rotational spectral analysis based on methods originally developed for oceanographic studies. This approach is deployed in a complex scenario of large‐amplitude GWs by applying it to reanalysis data. We divide the atmospheric region of interest into two height intervals. The simulations are compared with lidar measurements during one of the flights. From the degree of polarization and the total energy of the GWs, the contribution of the upward and downward wave packets is described as a function of their vertical wavenumbers. At low levels, a larger downward energy flux is observed in a few significant harmonics, suggesting inertial GWs radiated at polar night jet levels, and below, near to a cold front. In contrast, the upward GW energy flux, per unit area, is larger than the downward flux, as expected over mountainous areas. The main sub‐regions of upward GW energy flux are located above Patagonia, the Antarctic Peninsula and only some oceanic sectors. Above the sea, there are alternating sub‐regions dominated by linearly polarized GWs and sectors of downward GWs. At the upper levels, the total available GW energy per unit mass is higher than at the lower levels. Regions with different degrees of polarization are distributed in elongated bands. A satisfactory comparison is made with an analysis based on the phase difference between temperature and vertical wind disturbances. Plain Language Summary: Atmospheric gravity waves (GWs) are of great importance in the transport of energy and momentum through the atmosphere. Their sources can be broadly classified as stationary and non‐stationary. The southern tip of South America represents one of the most important natural laboratories for detecting the coexistence of large‐amplitude GWs. We present a spectral method to establish a semi‐quantitative classification of the different groups of GWs and their main vertical direction of propagation. We apply the method on the basis of global model data. We divide the lower and middle atmosphere into two vertical intervals and compare the model with data from one of the instruments deployed during the experiment. Based on the direction of rotation of the vector defined by the GW oscillations of the two horizontal wind components, we describe the net contribution of the upward and downward wave packets as a function of their spectral harmonics. The main sub‐regions of upward GW energy flux alternate with sub‐regions dominated by linearly polarized GWs and downward GW sectors mainly above the ocean. At the upper levels, the total available GW energy per unit mass is higher than at the lower levels. A comparison is made between these results and an independent analysis based on the known polarization relations for GWs. Key Points: A rotary spectral analysis is proposed to classify possible sources of gravity waves (GWs) according to their degree of polarizationFrom reanalysis data, the method is applied at a selected position during one of the flights of the SOUTHTRAC‐GW ExperimentUpward and downward GW structures from orographic and non‐orographic origin with different degrees of polarization are observed [ABSTRACT FROM AUTHOR]

This study provides a regional assessment of mean and extreme temperature and precipitation over South America south of 20°S under global warming of 1.5 °C, 2 °C, and 3 °C above pre-industrial level. A particular analysis is performed over four sub-regions: southeastern South America (SESA), Pampa, southern Patagonia (SPat), and northern Patagonia (NPat), where special interest is given to the differences in impacts between the global warming targets under analysis. Results indicate that the ongoing global warming will maintain and even stress the observed trends in the region. SESA is the region projected to experience the largest increases in both mean and extreme temperature and precipitation, and the magnitude of change becomes larger under the warmer global warming targets. The Patagonian regions are expected to suffer robust reductions in the frequency of frost days (fd) and ice days (id), and there appears to be a relationship between the target and the magnitude of decrease in fd and id over these regions. The present study shows that the degree of global warming will play a key role in determining the intensity and frequency of the climate extremes which could significantly affect the socio-economic activities in the selected climatic sensitive regions over southern South America. [ABSTRACT FROM AUTHOR]

Hunter-gatherer occupations of the forests of Patagonia are still not well understood compared to those of the open steppe and the coasts. The paucity of forest sites with a thorough chronological framework and the incomplete picture of climatehuman dynamics in such environments pose a challenge to understanding the occupations of such habitats. This paper presents recent work at the Las Quemas rockshelter, an archaeological site located in the Andean forests of the Aisén region (44°38'S) dating between 6100 and 2400 cal BP. We examine the context of the site, its rock art, and the technological and functional dimensions of its lithic assemblage. By comparing these records with local environmental reconstructions that report forest area fluctuations after the Post-Glacial period, this study provides novel data for a comprehensive regionalscale model of human occupations in central Patagonian forests. Following an initial mid-Holocene occupation, recurring occupational events at the site coincide with a significant contraction of forested area in the region during the late Holocene. The results are discussed in regard to regional archaeological data and current models of forest occupation in Patagonia. [ABSTRACT FROM AUTHOR]

Huanul is a shield volcano with several lava flows hosting mantle xenoliths erupted during the Pleistocene (0.84 ± 0.05 Ma). It is located in the southern part of the Payenia Volcanic Province, which is among the largest Neogene-Quaternary volcanic provinces of South America. The volcanism here has been ascribed as the northernmost expression of the back-arc volcanism of the Andean Southern Volcanic Zone. We present the first petrographic and mineral chemistry study of mantle xenoliths collected from Huanul lavas with the aim of reconstructing directly the mantle source of the Payenia Volcanic Province. Xenoliths are commonly small (<5 cm in radius) but scarcely crossed by basaltic veins. All xenoliths have a fertile lherzolitic modal composition and are equilibrated in the spinel-facies. Most of them exhibit an almost primitive-mantle geochemical affinity, characterized by slightly depleted clinopyroxene REE patterns reproducible by partial melting degrees between 0 and 4% of a PM source. Geothermobarometric P-T estimates of clinopyroxene-orthopyroxene couples form a linear trend between 10 and 24 kbar with constant increase of T from 814 to 1170 °C along a 50–60 mW/m2 geotherm. Evidences of interaction with the host basalts occur as spongy textures in clinopyroxene and reacted spinel, which tend to became more restitic in composition and show chromatographic or complete overprinting of the trace element compositions. The presence of plagioclase and calculated P-T values constrain this melt/rock reaction process between 6 and 14 kbar, during magma ascent, and fit the mantle adiabat model. Calculated melts in equilibrium with the primary clinopyroxenes do not fit the composition of the host basalt and, together with the geothermobarometric estimations, point to an asthenospheric mantle source for the magmatism in southern Payenia. The PM geochemical affinity of the xenoliths of Huanul is an extremely rare finding in the South America lithospheric mantle, which is commonly extensively refertilized by subduction-derived melts. [ABSTRACT FROM AUTHOR]

The Patagonian slab window has been proposed to enhance the solid Earth response to ice mass load changes in the overlying Northern and Southern Patagonian Icefields (NPI and SPI, respectively). Here, we present the first regional seismic velocity model covering the entire north‐south extent of the slab window. A slow velocity anomaly in the uppermost mantle indicates warm mantle temperature, low viscosity, and possibly partial melt. Low velocities just below the Moho suggest that the lithospheric mantle has been thermally eroded over the youngest part of the slab window. The slowest part of the anomaly is north of 49°S, implying that the NPI and the northern SPI overlie lower viscosity mantle than the southern SPI. This comprehensive seismic mapping of the slab window provides key evidence supporting the previously hypothesized connection between post‐Little Ice Age anthropogenic ice mass loss and rapid geodetically observed glacial isostatic uplift (≥4 cm/yr). Plain Language Summary: A gap in the subducting plate beneath Patagonia has enabled hotter, less viscous mantle material to flow underneath South America. Icefields in the Austral Andes above the gap in the plate have recently been shrinking, removing weight that had caused the continent to flex downward. We use seismic data to image the subsurface structure and find very low seismic velocity within and around the gap, as well as thinning of the rigid South American lithosphere overlying the gap. The low mantle velocity implies that mantle viscosity is also low beneath the shrinking icefields, and low viscosity enables the region to rebound upwards. Key Points: We observe anomalously low upper mantle shear wave velocities (<4.1 km/s) in the Patagonian slab windowThe lithospheric mantle has been thermally eroded over the youngest part of the slab windowLow viscosities in the slab window link observed rapid geodetic uplift to geologically recent ice mass loss in Patagonia [ABSTRACT FROM AUTHOR]

In the Cordillera Darwin, southernmost South America, we used 10Be and 14C dating, dendrochronology, and historical observations to reconstruct the glacial history of the Dalla Vedova valley from deglacial time to the present. After deglacial recession into northeastern Darwin and Dalla Vedova, by ~16 ka, evidence indicates a glacial advance at ~13 ka coeval with the Antarctic Cold Reversal. The next robustly dated glacial expansion occurred at 870 ± 60 calendar yr ago (approximately AD 1150), followed by less-extensive dendrochronologically constrained advances from shortly before AD 1836 to the mid-twentieth century. Our record is consistent with most studies within the Cordillera Darwin that show that the Holocene glacial maximum occurred during the last millennium. This pattern contrasts with the extensive early- and mid-Holocene glacier expansions farther north in Patagonia; furthermore, an advance at 870 ± 60 yr ago may suggest out-of-phase glacial advances occurred within the Cordillera Darwin relative to Patagonia. We speculate that a southward shift of westerlies and associated climate regimes toward the southernmost tip of the continent, about 900–800 yr ago, provides a mechanism by which some glaciers advanced in the Cordillera Darwin during what is generally considered a warm and dry period to the north in Patagonia. [ABSTRACT FROM AUTHOR]

The goal of this paper was to characterize fibers and vessel elements in the wood of Nothofagus nervosa (Phil.) Dim. et Mil., Nothofagaceae, (raulí), determining the variation of their lengths in the tree in radial and axial orientations and evaluating their variability between trees. Four trees with DBH (diameter at breast height) above 40 cm were used from Quilanlahue site, Neuquén, Argentina, from which sections were removed at three different heights. The north radius of each section was used and microscopic preparations and macerations were produced every ten years from pith to bark. The characteristics of fibers and vessel elements were described. The length of both cells was significantly greater in radial orientation from pith to bark. In axial orientation the length of the fiber is variable, while the length of vessel elements does not show significant changes. The greatest source of variation was observed in the tree related to the different ages at which wood was formed. A diminishing in the variation coefficient was observed for the length of fibers and vascular elements from twenty years of age of the tree. Variability among trees was not significant. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an updated, extensive review of glacier fluctuations during the past 1000years in the extratropical Andes of South America between ca. 17° and 55°S. Given the variety of environmental conditions and evidence available for glacier fluctuations across this wide latitudinal range, regional accounts are given for the Desert Andes (∼17°–31°S), the Andes of central Chile and Argentina (31°–36°S), and the North (36°–45°S) and South (45°–55°S) Patagonian Andes. The techniques, dating limitations, and interpretations of the glacier records along this transect are also discussed. Information on glacier fluctuations in the Desert Andes is limited to the 20th century. Documentation on past glacier variations is more abundant in the Central Chilean-Argentinean Andes, but the number of chronologies dealing with glacier fluctuations prior to the 1900s is also limited. Most records indicate that glaciers were generally more extensive prior to the 20th century, with dates of maximum expansion ranging from the 16th to the 19th centuries. The number and extent of glaciers increase significantly in the Patagonian region, where the evidence available for dating glacier variations during the past centuries is more abundant and the dating control for glacier events is generally better than in the northern parts of the study area. For some Patagonian glaciers, maximum Little Ice Age (LIA) or post-LIA advances have been precisely dated by dendro-geomorphological determinations or in situ measurements. However, for most sites, the evidence available is still preliminary and there is considerable variability in the extent and timing of events related to the maximum LIA expansion identified in most areas between the 16th and 19th centuries. Evidence is starting to appear at a growing number of sites for glacier advances during the first half of the past millennium. These events were generally less extensive than the LIA maximum pulses. Despite the occurrence of several post-LIA readvances over the past 100–110years, most areas in the Andes of extratropical South America have experienced a general pattern of glacier recession and significant ice mass losses. The differences in the glacier histories observed at local and regional scales probably reflect the inherent limitations associated with the glacier records and/or the dating techniques used in each case together with the varying dominance of precipitation, temperature and other climatic and non-climatic factors on glacier mass balance and glacier dynamics. These differences indicate that the late Holocene glacier history of southern South America is more complex than commonly assumed. The evidence discussed in this study highlights not only the immense potential for glaciological studies of this region but also a significant need for an increased number of detailed, well-dated records of glacier fluctuations. [Copyright &y& Elsevier]

Widespread changes in forest structure and distribution have been documented in northern Patagonia over the past century. We employed LPJ-GUESS, a dynamic global vegetation model (DGVM) to investigate the role of climate, atmospheric carbon dioxide (CO2), and fire on simulated forest cover during the twentieth century. Our objective was to assess the drivers responsible for forest change to temperature, precipitation, radiation, fire and atmospheric CO2 Results: Simulations using observed changes in climate and CO2 from 1930 to 2010, showed an increase in forest cover under changing climate and CO2, because of higher carbon assimilation and net primary production. The model results were compared with a remote-sensing-derived biomass map and 'greening' indices from the normalized difference vegetation index. Model simulations and satellite data both show increased greening at high and low elevations. In contrast, simulations using pre-industrial climate and CO2 conditions resulted in a decrease in fire frequency and lower simulated biomass than is reflected by present-day vegetation. Conclusion: Our simulations shows that climate is the primary driver and CO2 fertilization is the secondary driver of forest expansion in northern Patagonia. We suggest that rising CO2 mitigates climate-induced drought stress due to increases in water-use efficiency. [ABSTRACT FROM AUTHOR]

The Pleistocene–Holocene transition was a critical time for the dispersal of human societies all over South America. People looking for places to settle had to accept high environmental variability during the colonizing process. The case studied for this paper is Patagonia (Southern South America), where the oldest dates (ca. 13–10.5 ka BP) have been obtained for the peopling in the Deseado River Basin and Magellan Basin, as well. However, two archaeological sites yielded similar dates on the western side of the Andes (Monte Verde and Tagua Tagua).Following archaeological and palaeoenvironmental data (palynological, faunal, sedimentological and glaciological information), as well as radiocarbon datings, a hypothesis about the colonization of Patagonia is presented. Analysing the ways and time of colonization for this region, it is remarkable the coincidence of these ages in the centre of the steppe and close to the Magellan Strait, even in the present Tierra del Fuego island, though the eastern Andean foothills seems to be occupied at least two millennia later. It is proposed that independent peopling entries would have occurred both through the Atlantic and Pacific facades, and that the Andean foothills were colonized much later, only when the available spaces allowed it. [Copyright &y& Elsevier]

South America appears as a paradox for building the images of the New World''s human colonization. It is a paradox, because according to the models of the Peopling of America, it was the last part of the continent to be occupied by humans, but in spite of that sites as old as or older than the “Clovis” sites from North America, started to be discovered since the last century. It is a laboratory, because the amount of the Pleistocene archaeological sites is as great as their variability. In this way, since the last two decades, the hemi-continent is placed in a privileged situation for questioning and reconstructing theories concerning the first Americans, and also for answering questions as when did they arrive, how did they arrive, what strategies (social, ecological and economic) did they develop for the colonization of such different environments, which were their ideas for achieving this colonization, and how does their use of space and resources reflect in the archaeological record. The model “Clovis the first”, brings an image of unidirectional migration of the first people, from the great North American plains to southern Patagonia. For a decade, this model showed itself insufficient for explaining the great archaeological variability of America and especially for referring those South American contexts directly to a Clovis migration. The new findings in South America are creating more anomalies for this model, which predicts that the arrival of Pleistocene hunter–gatherers should be around 10,000 years in Patagonia. The object of this paper is to discuss these models in view of South American archaeological evidence, and thus propose answers for removing the paradox. The axes which are considered are: the geographical and chronological distribution of the main localities of Patagonia and South America; the function of the sites within regional mobility systems; the use of subsistence resources; the differences in the circulation of lithic raw materials; and the different taphonomical histories. These characteristics will be compared with models of social network among mobile peoples and American paleolandscapes at the Pleistocene/Holocene transition and a new alternative route of peopling in South America will be presented. In this sense, the data of Patagonia are highly relevant. [Copyright &y& Elsevier]

This paper models the extent of the Patagonian icesheet during the Last Glacial Maximum (LGM) and its subsequent deglaciation. It constrains a new coupled icesheet/climate numerical model with empirical evidence and simulates the icesheet at the LGM and at stages of deglaciation. Under LGM conditions an icesheet with a modelled volume slightly in excess of 500,000 km3 builds up along the Andes. There is a marked contrast between the maritime and continental flanks of the modelled icesheet, with positive mass balance exceeding 2 m in the west and declining tenfold to the east. Modelled ice velocities commonly reach 400 m yr−1 in the western fjords. The model is most sensitive to variations in temperature and good agreement between modelled ice extent and empirical evidence was achieved by applying a temperature decrease of 6°C relative to present day temperatures with constant wind fields over the model domain. Assuming a stepped start to deglaciation, modelled ice volumes declined sharply, contributing 1.2 m to global sea level, 80% of it within 2000 years. The empirical record suggests that such a stepped warming occurred around 17,500–17,150 cal yr ago. [Copyright &y& Elsevier]

The Late Cretaceous dinosaur record in southern South America has been improved recently; particularly with findings from Chorrillo and Cerro Fortaleza formations, both bearing ankylosaur remains, a clade that was not previously recorded in the Austral Basin. The dinosaur fauna of the type locality of Cerro Fortaleza Formation is known from -and biased to- large-sized sauropod remains and a single described taxon, the titanosaur Dreadnoughtus schrani. Here, we report the taxonomic composition of a site preserving thirteen isolated teeth and several osteoderms belonging to three dinosaur clades (Abelisauridae, Titanosauria, and Nodosauridae), and at least one clade of notosuchian crocodyliforms (Peirosauridae). They come from sediments positioned at the mid-section of the Cerro Fortaleza Formation, which is Campanian-Maastrichtian in age, adding valuable information to the abundance and biodiversity of this Cretaceous ecosystem. Since non-titanosaur dinosaur bones are almost absent in the locality, the teeth presented here provide a window onto the archosaur biodiversity of the Late Cretaceous in southern Patagonia. The nodosaurid tooth and small armor ossicles represent the first record of ankylosaurs for this stratigraphic unit. The peirosaurid material also represents the most austral record of the clade in South America. [ABSTRACT FROM AUTHOR]

The Notothenioidei are a typical example of stenothermal fishes since most species have evolved and lived in Antarctic waters, where the water temperature is low and stable. This fact enabled them to evolve physiological characteristics related to cold. Nevertheless, some species came out of Antarctic waters a few million years ago and coped with more variable thermal regimes. This work aims to determine the thermal tolerance and preference of two sub-Antarctic notothenioid species found in Southern South America, Patagonotothen tessellata and Harpagifer bispinis, adding valuable information about thermal adaptation mechanisms. Experiments were conducted after exposing their juveniles for three weeks at 4, 7, 10 and 12 °C. Their thermal tolerance limits were established using the Critical Thermal Methodology and their acute thermal preferenda, employing a horizontal thermal gradient tank. Fishes acclimated to different exposure temperatures had small to intermediate thermal tolerance polygons (P. tessellata: 593.85°C2, H. bispinis: 475.40 °C2) and positive relationships between preferred and acclimation temperatures. The Final Temperature Preferenda were estimated to be 14.25 °C for P. tessellata and 13.05 °C for H. bispinis, allowing to characterize them as cold eurythermal species, with P. tessellata more tolerant to heat and H. bispinis more tolerant to cold. Their different thermal sensitivities are in agreement with their different thermal histories and distributions. In a climate change context, the increase of sea surface temperatures is likely to reduce the northern boundaries of their distributions. Conversely, it can potentially enhance both species' performances at their southernmost distribution limits since those environments are cooler than their maximum thermal tolerances. [ABSTRACT FROM AUTHOR]

We compiled the numerous fossil records (486) assigned to Nothofagaceae including pollen grains (from surface sediments and continental and oceanic borehole cores), leaves, woods and reproductive structures from South America. All the records are revised and the latest systematic treatments and ages of the bearing strata of each record are followed. When possible, we proposed a subgeneric affinity to each record based on updated bibliography. Fossils of three (Nothofagus , Fuscospora and Lophozonia) of the four subgenera are found in similar proportions through time since the Late Cretaceous. Fossils with reliable affinity with subgenus Brassospora were not found in South America. Most of the records are concentrated in the southern tip of South America (Patagonia Region) and nearby areas. After a significant presence of Nothofagaceae in the Cretaceous, the family declined in diversity and abundance in the Palaeocene and then increased from the Eocene to the Miocene. In the Miocene, the records reach their maximum diversity and abundance, and Nothofagaceae usually dominate the assemblages of pollen, leaves and woods from Patagonia. Pliocene Nothofagaceae records are virtually absent, probably because sedimentary rocks of that age are rare in Patagonia. The fossil record for Nothofagaceae varies according to environmental turnover; when tropical/subtropical floras were present in Patagonia in the Palaeocene–early Eocene, Nothofagaceae contracted southwards and when open steppes developed in the Miocene of east Patagonia, Nothofagaceae contracted westward. [ABSTRACT FROM AUTHOR]

Coastal southeast South America is one of the classic locations where there are robust, spatially extensive records of past high sea level. Sea-level proxies interpreted as last interglacial (Marine Isotope Stage 5e, MIS 5e) exist along the length of the Uruguayan and Argentinian coast with exceptional preservation especially in Patagonia. Many coastal deposits are correlated to MIS 5e solely because they form the next-highest terrace level above the Holocene highstand; however, dating control exists for some landforms from amino acid racemization, U/Th (on molluscs), electron spin resonance (ESR), optically stimulated luminescence (OSL), infrared stimulated luminescence (IRSL), and radiocarbon dating (which provides minimum ages). As part of the World Atlas of Last Interglacial Shorelines (WALIS) database, we have compiled a total of 60 MIS 5 proxies attributed, with various degrees of precision, to MIS 5e. Of these, 48 are sea-level indicators, 11 are marine-limiting indicators (sea level above the elevation of the indicator), and 1 is terrestrial limiting (sea level below the elevation of the indicator). Limitations on the precision and accuracy of chronological controls and elevation measurements mean that most of these indicators are considered to be low quality. The database is available at 10.5281/zenodo.3991596. [ABSTRACT FROM AUTHOR]

Gripopterygidae is a diverse family of stoneflies, Plecoptera, distributed in the Southern Hemisphere. It has been traditionally divided into five subfamilies, but the monophyly of most of these is not supported by molecular the more comprehensive molecular analysis of the order. To test the monophyly of Antarctoperlinae, and to establish the phylogenetic position of a new Gripopterygidae species, we performed a morphological cladistic analysis including 38 morphological characters and 27 terminal taxa, with representatives of the four subfamilies present in South America and three Austroperlidae. Based on published information, we rooted the tree with Penturoperla barbata , Austroperlidae. As a result, Antarctoperlinae was recovered as polyphyletic, with Vesicaperla kuscheli and Plegoperla punctata , two members of the subfamily, placed outside the clade that includes the nine remaining genera of Antarctoperlinae. Vesicaperla also falls outside the family in previous molecular analysis. Based on this evidence, it should not be placed in Antarctoperlinae. Plegoperla punctata , known only from the type series, possesses many missing entries in our data matrix. Based on this, it seems convenient to maintain its subfamilial placement. In the tree obtained, the potential new species nests together with Pehuenioperla llaima. We thus accept it as a member of Pehuenioperla and describe it as P. microptera sp. nov. [ABSTRACT FROM AUTHOR]

Molecular phylogenetic analyses have addressed the systematic position of several major Northern Hemisphere lineages of Pezizales but the taxa of the Southern Hemisphere remain understudied. This study focuses on the molecular systematics and taxonomy of Southern Hemisphere species currently treated in the genera Underwoodia and Gymnohydnotrya. Species in these genera have been identified as the monophyletic/gymnohydnotrya lineage, but no further research has been conducted to determine the evolutionary origin of this lineage or its relationship with other Pezizales lineages. Here, we present a phylogenetic study of fungal species previously described in Underwoodia and Gymnohydnotrya, with sampling of all but one described species. We revise the taxonomy of this lineage and describe three new species from the Patagonian region of South America. Our results show that none of these Southern Hemisphere species are closely related to Underwoodia columnaris, the type species of the genus Underwoodia. Accordingly, we recognize the genus Geomorium described by Spegazzini in 1922 for G. fuegianum. We propose the new family, Geomoriaceae fam. nov., to accommodate this phylogenetically and morphologically unique Southern Hemisphere lineage. Molecular dating estimated that Geomoriaceae started to diverge from its sister clade Tuberaceae c. 112 MYA, with a crown age for the family in the late Cretaceous (c. 67 MYA). This scenario fits well with a Gondwanan origin of the family before the split of Australia and South America from Antarctica during the Paleocene-Eocene boundary (c. 50 MYA). [ABSTRACT FROM AUTHOR]

Ulota germana is an epiphytic moss moderately common in oceanic areas of Patagonia (southern South America), one of the regions of the world where Ulota reaches a peak of diversity. It is easily recognized by very long perichaetial leaves, which reach the capsule when wet, an endostome of eight segments and verrucose spores. In Nikolajs Malta's revision of South American Ulota, a species was described under this name with apparently similar long perichaetial leaves and spores but with a 16-segment endostome, an uncommon character in this genus. No further references to this particular combination of traits are found throughout the literature of South American Ulota. In the same work, Malta also published U. germana var. breviseta. During the study of recent Patagonian collections, a moss similar to that described by Malta was repeatedly found, living together with U. germana s.str. To ascertain the name and taxonomic identity of the new specimens and Malta's moss, a detailed morphological comparative study was carried out. Original material of relevant names was analyzed, demonstrating that the gatherings on which those names are based were usually a mixture of several species, thus resulting in nomenclatural confusion. Having established that the plants described by Malta at both specific and varietal ranks are not U. germana, we formally describe them as U. maltiana with a complete description and illustration. Ulota germana s.str. is also illustrated for comparison. The reasons behind Malta's error are discussed. We demonstrate that the previous typification of U. germana was incorrect, and propose a new lectotypification for this species and for U. germana var. breviseta. [ABSTRACT FROM AUTHOR]

The current study presents an assessment of the impact of climate change on water yield, one of the main hydrological ecosystem services, in northern Patagonia. The outputs of regional climate models from the CORDEX Project for South America were used to drive the InVEST water yield model. CORDEX regional climate models project for the far future (2071–2100) an increase in temperature higher than 1.5 °C and a precipitation decrease ranging from − 10 to − 30% for the study area. The projected warmer and dryer climate emerges as a robust signal based on model agreement and on consistent physical drivers of these changes. Moreover, both the projected increase in evapotranspiration and the decrease in precipitation contribute to a strong decrease in water yield of around − 20 to − 40% in the headwaters of northern Patagonian watersheds. Comparison of the results in the two basins reveals that the land cover may be considered a buffer of water yield changes and highlights the key role of protected areas in reducing the vulnerability of water resources to climate change. [ABSTRACT FROM AUTHOR]

Premise: Eocene floras of Patagonia document biotic response to the final separation of Gondwana. The conifer genus Araucaria, distributed worldwide during the Mesozoic, has a disjunct extant distribution between South America and Australasia. Fossils assigned to Australasian Araucaria Sect. Eutacta usually are represented by isolated organs, making diagnosis difficult. Araucaria pichileufensis E.W. Berry, from the middle Eocene Río Pichileufú (RP) site in Argentine Patagonia, was originally placed in Sect. Eutacta and later reported from the early Eocene Laguna del Hunco (LH) locality. However, the relationship of A. pichileufensis to Sect. Eutacta and the conspecificity of the Araucaria material among these Patagonian floras have not been tested using modern methods. Methods: We review the type material of A. pichileufensis alongside large (n = 192) new fossil collections of Araucaria from LH and RP, including multi‐organ preservation of leafy branches, ovuliferous complexes, and pollen cones. We use a total evidence phylogenetic analysis to analyze relationships of the fossils to Sect. Eutacta. Results: We describe Araucaria huncoensis sp. nov. from LH and improve the whole‐plant concept for Araucaria pichileufensis from RP. The two species respectively resolve in the crown and stem of Sect. Eutacta. Conclusions: Our results confirm the presence and indicate the survival of Sect. Eutacta in South America during early Antarctic separation. The exceptionally complete fossils significantly predate several molecular age estimates for crown Eutacta. The differentiation of two Araucaria species demonstrates conifer turnover during climate change and initial South American isolation from the early to middle Eocene. [ABSTRACT FROM AUTHOR]

Population connectivity is driven by individual dispersal potential and modulated by natal philopatry. In seabirds, high vagility facilitates dispersal yet philopatry is also common, with foraging area overlap often correlated with population connectivity. We assess the interplay between these processes by studying past and current connectivity and foraging niche overlap among southern rockhopper penguin colonies of the coast of southern South America using genomic and stable isotope analyses. We found two distinct genetic clusters and detected low admixture between northern and southern colonies. Stable isotope analysis indicated niche variability between colonies, with Malvinas/Falklands colonies encompassing the species entire isotopic foraging niche, while the remaining colonies had smaller, nonoverlapping niches. A recently founded colony in continental Patagonia differed in isotopic niche width and position with Malvinas/Falklands colonies, its genetically identified founder population, suggesting the exploitation of novel foraging areas and/or prey items. Additionally, dispersing individuals found dead across the Patagonian shore in an unusual mortality event were also assigned to the northern cluster, suggesting northern individuals reach southern localities, but do not breed in these colonies. Facilitated by variability in foraging strategies, and especially during unfavorable conditions, the number of dispersing individuals may increase and enhance the probability of founding new colonies. Metapopulation demographic dynamics in seabirds should account for interannual variability in dispersal behavior and pay special attention to extreme climatic events, classically related to negative effects on population trends. [ABSTRACT FROM AUTHOR]

Patagonia is thought to be one of the wettest regions on Earth, although available regional precipitation estimates vary considerably. This uncertainty complicates understanding and quantifying the observed environmental changes, such as glacier recession, biodiversity decline in fjord ecosystems and enhanced net primary production. The Patagonian Icefields, for example, are one of the largest contributors to sea-level rise outside the polar regions, and robust hydroclimatic projections are needed to understand and quantify current and future mass changes. The reported projections of precipitation from numerical modelling studies tend to overestimate those from in situ determinations, and the plausibility of these numbers has never been carefully scrutinized, despite the significance of this topic to our understanding of observed environmental changes. Here I use simple physical arguments and a linear model to test the plausibility of the current precipitation estimates and its impact on the Patagonian Icefields. The results show that environmental conditions required to sustain a mean precipitation amount exceeding 6.09±0.64 m yr -1 are untenable according to the regional moisture flux. The revised precipitation values imply a significant reduction in the surface mass balance of the Patagonian Icefields compared to previously reported values. This yields a new perspective on the response of Patagonia's glaciers to climate change and their sea-level contribution and might also help reduce uncertainties in the change of other precipitation-driven environmental phenomena. [ABSTRACT FROM AUTHOR]

Background. In extant ecosystems, complex networks of ecological interactions between organisms can be readily studied. In contrast, understanding of such interactions in ecosystems of the geologic past is incomplete. Specifically, in past terrestrial ecosystems we know comparatively little about plant biotic interactions besides saprotrophy, herbivory, mycorrhizal associations, and oviposition. Due to taphonomic biases, epiphyte communities are particularly rare in the plant-fossil record, despite their prominence in modern ecosystems. Accordingly, little is known about how terrestrial epiphyte communities have changed across geologic time. Here, we describe a tiny in situ fossil epiphyte community that sheds light on plant-animal and plant-plant interactions more than 50 million years ago. Methods. A single silicified Todea (Osmundaceae) rhizome from a new locality of the early Eocene (ca. 52 Ma) Tufolitas Laguna del Hunco (Patagonia, Argentina) was studied in serial thin sections using light microscopy. The community of organisms colonizing the tissues of the rhizome was characterized by identifying the organisms and mapping and quantifying their distribution. A 200 X 200 mm grid was superimposed onto the rhizome cross section, and the colonizers present at each node of the grid were tallied. Results. Preserved in situ, this community offers a rare window onto aspects of ancient ecosystems usually lost to time and taphonomic processes. The community is surprisingly diverse and includes the first fossilized leafy liverworts in South America, also marking the only fossil record of leafy bryophyte epiphytes outside of amber deposits; as well as several types of fungal hyphae and spores; microsclerotia with possible affinities in several ascomycete families; and evidence for oribatid mites. Discussion. The community associated with the Patagonian rhizome enriches our understanding of terrestrial epiphyte communities in the distant past and adds to a growing body of literature on osmundaceous rhizomes as important hosts for component communities in ancient ecosystems, just as they are today. Because osmundaceous rhizomes represent an ecological niche that has remained virtually unchanged over time and space and are abundant in the fossil record, they provide a paleoecological model system that could be used to explore epiphyte community structure through time. [ABSTRACT FROM AUTHOR]

This article examines the policies that have transformed water into a market commodity in Chile. Graciela Muñoz, an artist born and raised in one of the country's areas affected by the drought produced by these policies, travelled to Chilean Patagonia to record the sound of the Baker River, and transferred its sounds to 28 small loudspeakers installed on the dry riverbed of the Petorca River, near her hometown. Through this soundscape, Muñoz temporarily recovered a lost experience where a river that does not exist anymore appears again, in sound, superimposing the past over a uncertain present. [ABSTRACT FROM AUTHOR]

Macrofossil impressions of caytonialean leaves and micro- and megasporangiate organs from the Early Jurassic Taquetrén locality in Patagonia, Argentina, are described based on more than 300 hand specimens. Leaves of the organ-genus Sagenopteris are described using both discrete and continuous features allowing us to erect the species Sagenopteris trapialensis sp. nov. Associated microsporangiate organs of Caytonanthus type are the first recorded for South America and are characterized by a unique combination of architecture, size and type of dehiscence. Two specimens, one resembling an isolated Caytonia cupule, and the other a Caytonia axis, are also described. The availability of a collection with numerous specimens has proven to be an important tool in order to fully understand the intraspecific morphological plasticity of the studied species. The striking morphological resemblance of both vegetative and reproductive organ-genera with their Northern Hemisphere counterparts suggests that they were part of the same lineage, which was widely distributed during the Jurassic. Well-defined whole-plant concepts are still needed to advance the goal of deciphering the internal relationships of caytonialeans in particular, and their relationships with other groups of seed-plants in general, and thorough macro-morphological characterization of the organs that compose them, as we present here, may be of valuable use in achieving it. [ABSTRACT FROM AUTHOR]

The middle to late Miocene Friasian sensu stricto, Colloncuran and Mayoan South American Land Mammal Ages (SALMAs) were established based on the mammals recovered from the Río Frías, Collón Curá and Río Mayo formations, respectively (southern Argentina and Chile). Records of Interatheriinae (Notoungulata) from these sediments have been known since the first contributions of Ameghino and Roth, but most of this material has only been superficially revised or is almost unstudied. Based on these old collections and new interatheriine records from Cerro Zeballos (Chubut Province), we improve the diagnosis of Caenophilus tripartitus, describe new and peculiar characters for this taxon, consider Epipatriarchus bifidens as Protypotherium cf. colloncurensis, and propose Epipatriarchus as a junior synonym of Protypotherium. In turn, the holotype of Epipatriarchus innexus is here identified as the mesotheriid Trachytypotherium sp. Therefore, only two genera of Interatheriinae, Protypotherium and Caenophilus, are recognized in the Friasian sensu stricto and Mayoan. We identify Protypotherium cf. endiadys and a probable new species of Protypotherium for the Friasian sensu stricto, P. cf. colloncurensis and Caenophilus tripartitus for the Mayoan, and C. tripartitus, P. colloncurensis and P. cf. endiadys for Cerro Zeballos. An extended phylogenetic analysis is performed, including species from low latitudes and new data for P. colloncurensis and Caenophilus tripartitus, with the latter recovered as a sister taxon to Miocochilius federicoi. Both Protypotherium and Miocochilius are recovered as paraphyletic. The updated information we present provides a better knowledge of Interatheriinae for the middle to late Miocene of southern South America. [ABSTRACT FROM AUTHOR]

A paleomagnetic and geochronologic study was carried out on Late Permian-to-Early Triassic magmatic units exposed in the North Patagonian Massif, near the locality of Estancia La Esperanza (Río Negro Province, Argentina), to provide better paleogeographic and tectonic constraints on the evolution of Patagonia and its relations with Gondwana in the Late Paleozoic–Early Mesozoic. The study included the Late Permian (264 ± 2 Ma) Rhyolite Dome, the Collinao Dacite, for which we obtained a U–Pb zircon crystallization age of 253 ± 2 Ma, several basic dikes, that intrude older granite units (255 ± 2 Ma), and a swarm of acidic dikes for which an Early Triassic age had been previously assigned that we confirmed with a U–Pb zircon age of 244 ± 2 Ma. A paleomagnetic pole (C), computed on the basis of seven VGPs, was obtained for the Collinao Dacite and associated units (48.3°S, 349.9°E, N = 7, A95 = 15.1°). A single VGP for the somewhat older Rhyolite Dome falls close to that pole. A second paleomagnetic pole (A) which strongly disagrees with the C position was computed based on 12 VGPs from the same number of acidic dikes (87°S, 51.5°E, N = 12, A95 = 8.1°). The basic dikes, with ages bracketed between the dacitic and the rhyolitic dikes, yielded four VGPs, two of which are consistent with the C pole and the other two are close to the A pole. The C pole falls on a much older position (Late Carboniferous) on different Gondwana/South America reference paths, which is clearly anomalous based on its Late Permian age. The A pole, in turn, is consistent with the 250/240 Ma paleomagnetic poles in most reference paths for Gondwana/South America. Either regional tilting or rotation around a vertical axis to explain the anomalous C pole is unlikely considering the local geological evidence. A working model is presented to explain the discrepancy as due to around 30° CCW rotation of the whole North Patagonian Massif during the latest Permian and earliest Triassic, closing a V-shaped basin that separated it from southern Gondwana, as the final stages of collision of an allochthonous or para-autochthonous Patagonia terrane. This hypothesis is consistent with Late Permian-to-Early Triassic evidence of deformation in the Hespérides Basin as well as in northern Patagonia. Scarce previous paleomagnetic data from this region can be reconciled with this model, considering that they are very loosely constrained in age. [ABSTRACT FROM AUTHOR]

Exotic species introductions are a global phenomenon and protected areas are susceptible to them. Understanding the drivers of exotic species richness is vital for prioritizing natural resource management, particularly in developing countries with limited resources. We analyzed the influence of coarse resolution factors on exotic species richness (plants, mammals, and birds) in Argentina's National Parks System. We collected data on native species richness, year of park formation, park area, region, elevation range, number of rivers crossing area boundaries, roads entering area, mean annual rainfall, mean annual temperature, mean annual number of visitors, and Human Influence Index within and surrounding each park. We compiled 1,688 exotic records in 36 protected areas: 83% plants and 17% animals (9.5% mammals, 5.5% birds, 1.5% fishes, 0% amphibians, 0% reptiles). The five parks with the most exotic species (all taxa combined) were in north Patagonia. Exotic grasses were the most common exotic plants, and within animals, lagomorphs and feral ungulates were remarkably widespread. Exotic plant richness was mostly influenced by temperature and native plant richness, while exotic mammal and bird richness was driven mostly by anthropogenic variables, with models explaining 36-45% of data deviance. Most variables that positively influenced exotic taxa were indirectly related to an increase in spatial heterogeneity (natural or anthropogenic), suggesting greater niche space variability as facilitators of exotic richness increase. Additional data are needed to further investigate the patterns and mechanisms of exotic species richness in protected areas, which will help to prioritize the greatest needs of monitoring and management. [ABSTRACT FROM AUTHOR]

• Background and Aims Early Palaeocene (Danian) plant fossils from Patagonia provide information on the recovery from the end-Cretaceous extinction and Cenozoic floristic change in South America. Actinomorphic flowers with eight to ten perianth parts are described and evaluated in a phylogenetic framework. The goal of this study is to determine the identity of these fossil flowers and to discuss their evolutionary, palaeoecological and biogeographical significance. • Methods More than 100 fossilized flowers were collected from three localities in the Danian Salamanca and Peñas Coloradas Formations in southern Chubut. They were prepared, photographed and compared with similar extant and fossil flowers using published literature and herbarium specimens. Phylogenetic analysis was performed using morphological and molecular data. • Key results The fossil flowers share some but not all the synapomorphies that characterize the Schizomerieae, a tribe within Cunoniaceae. These features include the shallow floral cup, variable number of perianth parts arranged in two whorls, laciniate petals, anthers with a connective extension, and a superior ovary with free styles. The number of perianth parts is doubled and the in situ pollen is tricolporate, with a surface more like that of other Cunoniaceae outside Schizomerieae, such as Davidsonia or Weinmannia. • Conclusions An extinct genus of crown-group Cunoniaceae is recognized and placed along the stem lineage leading to Schizomerieae. Extant relatives are typical of tropical to southern-temperate rainforests, and these fossils likely indicate a similarly warm and wet temperate palaeoclimate. The oldest reliable occurrences of the family are fossil pollen and wood from the Upper Cretaceous of the Antarctica and Argentina, whereas in Australia the family first occurs in upper Palaeocene deposits. This discovery demonstrates that the family survived the Cretaceous-Palaeogene boundary event in Patagonia and that diversification of extant lineages in the family was under way by the earliest Cenozoic. [ABSTRACT FROM AUTHOR]

Balaenidae (right and bowhead whales) are a key group in understanding baleen whale evolution, because they are the oldest surviving lineage of crown Mysticeti, with a fossil record that dates back ∼20 million years. However, this record is mostly Pliocene and younger, with most of the Miocene history of the clade remaining practically unknown. The earliest recognized balaenid is the early Miocene Morenocetus parvus Cabrera, 1926 from Argentina. M. parvus was originally briefly described from two incomplete crania, a mandible and some cervical vertebrae collected from the lower Miocene Gaiman Formation of Patagonia. Since then it has not been revised, thus remaining a frequently cited yet enigmatic fossil cetacean with great potential for shedding light on the early history of crown Mysticeti. Here we provide a detailed morphological description of this taxon and revisit its phylogenetic position. The phylogenetic analysis recovered the middle Miocene Peripolocetus as the earliest diverging balaenid, and Morenocetus as the sister taxon of all other balaenids. The analysis of cranial and periotic morphology of Morenocetus suggest that some of the specialized morphological traits of modern balaenids were acquired by the early Miocene and have remained essentially unchanged up to the present. Throughout balaenid evolution, morphological changes in skull arching and ventral displacement of the orbits appear to be coupled and functionally linked to mitigating a reduction of the field of vision. The body length ofMorenocetus and other extinct balaenids was estimated and the evolution of body size in Balaenidae was reconstructed. Optimization of body length on our phylogeny of Balaenidae suggests that the primitive condition was a relatively small body length represented by Morenocetus, and that gigantism has been acquired independently at least twice (in Balaena mysticetus and Eubalaena spp.), with the earliest occurrence of this trait in the late Miocene–early Pliocene as represented by Eubalaena shinshuensis. [ABSTRACT FROM AUTHOR]

Delimiting species is an important, but frequently difficult aspect of systematics that should be addressed using data from multiple sources. Here we combine morphometric analyses and environmental characteristics to delimit species in the South Andean and Patagonian taxonomically difficult species-group composed byMulinum spinosum,M. echinusandM. leptacanthum(Apiaceae-Azorelloideae). Molecular phylogenies have shown that these three species form part of a polytomy together with otherMulinumspecies, and therefore these data are not useful for their delimitation. We include measurements of 25 morphometric variables from 163 herbarium specimens and perform univariate and multivariate principal component analysis (PCA) and discriminant analysis (DA) to establish the limits amongst the three mostly sympatric, morphologically similar, and phylogenetically unresolved species. We also use 19 bioclimatic and three geographic variables from localities of the specimens to infer environmental characteristics of the taxa and test their relation with morphological variation. Morphological evidence supports the inclusion ofM. echinuswithin the morphologically and climatically variableM. spinosum, and rejects its recognition as a distinct taxon at any rank. On the contrary,M. leptacanthumis considered a morphologically distinct species, generally restricted to high altitude areas of the southern Andes with a cooler and wetter climate. Within the widespreadM. spinosum, environmental gradients of precipitation and temperature relate to morphological gradients (e.g., in leaf and inflorescence sizes, in leaf acicularity, and in fruit-wing width). These last results showed that the large morphological variation in vegetative and reproductive characteristics of this species that grows in arid and semiarid habitats are related to regional climatic gradients that have probably been important in the evolution of this species' plasticity, diversification, and differentiation. [ABSTRACT FROM AUTHOR]

Few studies have examined in detail the sequence of events during the last glacial termination (T1) in the core sector of the Patagonian Ice Sheet (PIS), the largest ice mass in the Southern Hemisphere outside of Antarctica. Here we report results from Lago Edita (47°80 S, 72°250W, 570ma.s.l.), a small closed-basin lake located in a valley overridden by eastward-flowing Andean glaciers during the Last Glacial Maximum (LGM). The Lago Edita record shows glaciolacustrine sedimentation until 19 400 yr BP, followed by organic sedimentation in a closed-basin lake and a mosaic of cold-resistant hygrophilous conifers and rainforest trees, along with alpine herbs between 19 400 and 11 000 yr BP. Our data suggest that the PIS retreated at least ~90 km from its LGM limit between ~21 000 and 19 400 yr BP and that scattered, low-density populations of cold-resistant hygrophilous conifers, rainforest trees, high-Andean and steppe herbs thrived east of the Andes during the LGM and T1, implying high precipitation levels and southern westerly wind (SWW) influence at 47° S. The conifer Podocarpus nubigena increased between 14 500 and 13 000 yr BP, suggesting even stronger SWW influence during the Antarctic Cold Reversal, after which it declined and persisted until 11 000 yr BP. Large increases in arboreal pollen at ~13 000 and ~11 000 yr BP led to the establishment of forests near Lago Edita between 10 000 and 9000 yr BP, suggesting a rise in the regional tree line along the eastern Andean slopes driven by warming pulses at ~13 000 and ~11 000 yr BP and a subsequent decline in SWW influence at ~11 000 yr BP. We propose that the PIS imposed a regional cooling signal along its eastern, downwind margin through T1 that lasted until the separation of the northern and southern Patagonian ice fields along the Andes during the Younger Dryas period. We posit that the withdrawal of glacial and associated glaciolacustrine environments through T1 provided a route for the dispersal of hygrophilous trees and herbs from the eastern flank of the central Patagonian Andes, contributing to the afforestation of the western Andean slopes and pacific coasts of central Patagonia during T1. [ABSTRACT FROM AUTHOR]

Many mountainous regions worldwide are characterized by harsh environments, scarce infrastructure, and extreme contrasts between mountains and neighboring plateaus and plains. Transhumance is a social adaptation to handle geomorphological heterogeneity such as lowlands and highlands, and to cope with environmental variability (seasonal and regional rainfall and snowfall). We studied the regional transhumant system with a network approach in the Andes of North Patagonia, Argentina. We measured the connectivity promoted by the seasonal movements of herds and people (relationships) among different ecosystems (nodes), defined as winter and summer lands. We identified 238 networks. The highest frequencies corresponded to small network structures (dyads and triads), suggesting that landscape management is highly decentralized. Network complexity was positively related to ecological richness and diversity of connected nodes. However, most networks were dependent upon a central node, suggesting vulnerable situations regarding disturbances affecting such key nodes. The identification of social-ecological traps of this mobile system provided novel insights for policy decision making, which otherwise would not be evidenced with traditional approaches. Management proposals and policy making should consider the spatial and temporal scales of transhumant pastoralism, in order to avoid problems derived from fixation logics, scale mismatches, and disconnection. [ABSTRACT FROM AUTHOR]

In this work, we assessed the feasibility of using optical flow to obtain the motion estimation of a glacier. In general, former investigations used to detect glacier changes involve solutions that require repeated observations which are many times based on extensive field work. Taking into account glaciers are usually located in geographically complex and hard to access areas, deploying time-lapse imaging sensors, optical flow may provide an efficient solution at good spatial and temporal resolution to describe mass motion. Several studies in computer vision and image processing community have used this method to detect large displacements. Therefore, we carried out a test of the proposed Large Displacement Optical Flow method at the Viedma Glacier, located at South Patagonia Icefield, Argentina. We collected monoscopic terrestrial time-lapse imagery, acquired by a calibrated camera at every 24 hour from April 2014 until April 2015. A filter based on temporal correlation and RGB color discretization between the images was applied to minimize errors related to changes in lighting, shadows, clouds and snow. This selection allowed discarding images that do not follow a sequence of similarity. Our results show a flow field in the direction of the glacier movement with acceleration in the terminus. We analyzed the errors between image pairs, and the matching generally appears to be adequate, although some areas show random gross errors related to the presence of changes in lighting. The proposed technique allowed the determination of glacier motion during one year, providing accurate and reliable motion data for subsequent analysis. [ABSTRACT FROM AUTHOR]

This work evaluates the consequences of anthropogenic pressures at different sections of a Patagonian mountain river using a set of environmental and biological measures. A map of risk of soil erosion at a basin scale was also produced. The study was conducted at 12 sites along the Percy River system, where physicochemical parameters, riparian ecosystem quality, habitat condition, plants, and macroinvertebrates were investigated. While livestock and wood collection, the dominant activities at upper and mean basin sites resulted in an important loss of the forest cover still the riparian ecosystem remains in a relatively good status of conservation, as do the in-stream habitat conditions and physicochemical features. Besides, most indicators based on macroinvertebrates revealed that both upper and middle basin sections supported similar assemblages, richness, density, and most functional feeding group attributes. Instead, the lower urbanized basin showed increases in conductivity and nutrient values, poor quality in the riparian ecosystem, and habitat condition. According to the multivariate analysis, ammonia level, elevation, current velocity, and habitat conditions had explanatory power on benthos assemblages. Discharge, naturalness of the river channel, flood plain morphology, conservation status, and percent of urban areas were important moderators of plant composition. Finally, although the present land use in the basin would not produce a significant risk of soil erosion, unsustainable practices that promotes the substitution of the forest for shrubs would lead to severe consequences. Mitigation efforts should be directed to protect headwater forest, restore altered riparian ecosystem, and to control the incipient eutrophication process. [ABSTRACT FROM AUTHOR]

Caviomorph rodents, the New World Hystricognathi, are one of the most characteristic groups of South American mammals. Although they have been in the continent at least since the middle Eocene, those of the Deseadan Land mammal Age (early–late Oligocene) are the best source to understanding their early history due of their good record, large geographic distribution and good temporal calibration of many of the local faunas. Here, we describe the following new taxa from the classical locality of Cabeza Blanca: Octodontoidea AcaremyidaeGalileomys baiosn. sp., Octodontoidea incertae sedisEthelomys loomisin. gen.,n. comb.,Acarechimys leucotheaen. sp.,Protacaremys? adilosn. sp., Chinchilloidea incertae sedisLoncolicu tretosn. gen., n. sp.,Incamys menniorumn. sp., Caviomorpha incertae sedisLlitun notucan. gen., n. sp.,Leucokephalos zeffiaen. gen., n. sp.and CephalomyidaeCephalomys ceciaen. sp. The DP4 of an ‘eocardiid’,Asteromys punctus? is described for the first time. These new taxa allow us to reinterpret the relationships of some of the previously known Deseadan species and genera. They show a great early diversification at least for extra Andean Patagonia, involving at least three of the main caviomorph lineages: octodontoids, chinchilloids and cavioids. [ABSTRACT FROM AUTHOR]

The article discusses a study on the estimated density and population size of Lama guanicoe guanacos over major environmental gradients of Santa Cruz in southern Patagonia. Topics covered include the use of road surveys and distance sampling, spatial variation in density, and high guanaco abundance in arid lands. Also mentioned are the benefits of sustainable use of guanaco populations including rural areas' socioeconomic progress and the eventual restoration of shrub-steppes.