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Introduction and objectives: The genus Pilosella is native to Europe and Asia, but its species are successful invaders on most continents. These species form an agamic complex with common apomixis. Apomictic species hybridize and have different degree of residual sexuality. Main aim of this paper was to determine if interspecific hybridization already occurred in Patagonia. M&M: We analysed seed progeny collected at thirteen populations of Pilosella in southern Argentina and Chile. The taxonomic identity of plants, DNA ploidy level (using flow cytometry), chromosome number, reproduction, formation of parthenogenetic seeds and clonal identity (using isozyme phenotypes) were examined. Results: No mixed-species population was recorded. Two apomictic clones of P. officinarum (one pentaploid and the other hexaploid) were found in populations: eight were hexaploid and one was mixed in cytotype composition. A new species for Patagonia, the apomictic pentaploid P. caespitosa, was represented by plants from two Argentinean populations. Some of the progeny plants, cultivated from seeds sampled at three localities, represented seed-fertile aneuploids the morphology of which suggest a hybrid origin with P. officinarum as one of the parental species. Conclusions: The presence of seed-fertile, aneuploid and parthenogenetic hybrids among the cultivated plants signifies an increased risk of the formation of new hybridogeneous genotypes of Pilosella in southern Patagonia. [ABSTRACT FROM AUTHOR]

This paper presents a detailed record of volcanism extending back to ∼80 kyr BP for southern South America using the sediments of Laguna Potrok Aike (ICDP expedition 5022; Potrok Aike Maar Lake Sediment Archive Drilling Project - PASADO). Our analysis of tephra includes the morphology of glass, the mineral componentry, the abundance of glass-shards, lithics and minerals, and the composition of glass-shards in relation to the stratigraphy. Firstly, a reference database of glass compositions of known eruptions in the region was created to enable robust tephra correlations. This includes data published elsewhere, in addition to new glass-shard analyses of proximal tephra deposits from Hudson (eruption units H 1 and H 2), Aguilera (A 1), Reclus (R 1 , R 2-3), Mt Burney (MB 1 , MB 2 , MB x , MB 1910) and historical Lautaro/Viedma deposits. The analysis of the ninety-four tephra layers observed in the Laguna Potrok Aike sedimentary sequence reveals that twenty-five tephra deposits in the record are the result of primary fallout and are sourced from at least three different volcanoes in the Austral Andean Volcanic Zone (Mt Burney, Reclus, Lautaro/Viedma) and one in the southernmost Southern Volcanic Zone (Hudson). One new correlation to the widespread H 1 eruption from Hudson volcano at 8.7 (8.6–9.0) cal ka BP during the Quaternary is identified. The identification of sixty-five discrete deposits that were predominantly volcanic ashes (glass and minerals) with subtle characteristics of reworking (in addition to three likely reworked tephra, and one unknown layer) indicates that care must be taken in the analysis of both visible and invisible tephra layers to decipher their emplacement mechanisms. • Major element glass compositions of visible tephra units deposited over the last ∼80,000 years. • Compositions of widespread marker layers are also presented to verify correlations. • Numerous reworked tephra layers are preserved. • Improved understanding of past eruptive frequency from southern Chile. • New correlations to Hudson, Reclus, and Mt Burney volcanoes. [ABSTRACT FROM AUTHOR]

Differences between climate conditions during the Last Glacial Maximum (LGM) and the Mid-Holocene (MH) in southern South America inferred from the state-of-the-art PMIP3 paleoclimatic simulations are described for the first time in this paper. The aim is to expose characteristics of past climate changes occurred without human influence. In this context, numerical simulations are an indispensable tool for inferring changes in near-surface air temperature and precipitation in regions where proxy information is scarce or absent. The analyzed PMIP3 models describe MH temperatures significantly warmer than those of LGM with magnitudes of change depending on the season and the specific geographic region. In addition, models indicate that seasonal mean precipitation during MH increased with respect to LGM values in wide southern continental areas to the east of the Andes Cordillera whereas seasonal precipitation developed in areas to the west of Patagonian Andes reduced from LGM to MH. [ABSTRACT FROM AUTHOR]

This paper is a pioneering analysis of past climates in southern South America combining multiproxy reconstructions and the state-of-the-art CMIP5/PMIP3 paleoclimatic models to investigate the time evolution of regional climatic conditions from the Mid-Holocene (MH) to the present. This analysis allows a comparison between the impact of the long term climate variations associated with insolation changes and the more recent effects of anthropogenic forcing on the region. The PMIP3 multimodel experiments suggest that changes in precipitation over almost all southern South America between MH and pre-industrial (PI) times due to insolation variations are significantly larger than those between PI and the present, which are due to changes in greenhouse gas concentrations. Anthropogenic forcing has been particularly intense over western Patagonia inducing reduction of precipitation in summer, autumn and winter as a consequence of progressively weaker westerly winds over the region, which have moved further poleward, between ca. 35-55°S and have become stronger south of about 50°S. Orbital variations between the MH to the PI period increased insolation over southern South America during summer and autumn inducing warmer conditions in the PI, accentuated by the effect of anthropogenic forcing during the last century. On the other hand, changes in orbital parameters from the MH to the PI period reduced insolation during winter and spring inducing colder conditions, which have been reversed by the anthropogenic forcing. [ABSTRACT FROM AUTHOR]

This paper is the first analysis of differences between Last Glacial Maximum (LGM) and present climates in southern South America considering the state-of-the-art PMIP3 paleoclimatic models. The study is focused on characteristics of temperature and precipitation over the portion of the continent to the south of 20°S at both sides of the Andes Cordillera. Results demonstrate that model outputs coincide with glacial conditions inferred from the very few paleorecords available in the region. Consequently, these models are a valuable tool for inferring additional conditions in areas where there is a lack of proxy information allowing the reconstruction of the past climate at regional scales. The analyzed PMIP3 models expose an LGM cooling of ∼2-5 °C throughout the year over almost all southern South America but differences are even more pronounced in areas around the southern Andes. Models also suggest that LGM precipitation was substantially lower than present over the portion of southern South America to the east of the Andes inferring reductions of ∼20–30% with respect to present-day values in subtropical areas and ∼40–50% in the southern tip of the continent. [ABSTRACT FROM AUTHOR]

In 1851 a small party of British missionaries died of scurvy and starvation in Tierra del Fuego. Led by retired Royal Navy commander Allen Gardiner, the expedition was poorly planned, lacked reliable supplies, and faced relentless hostility from the indigenous Yaghan. Nevertheless, Gardiner and his companions would not be remembered as failures. Scurvy, an iconic disease of exploration and empire, became an icon of missionary martyrdom. Extensive journals and other papers were recovered from the unburied bodies of the last of the group to survive, including Gardiner himself. This rich archive includes the journal of Richard Williams, a surgeon turned missionary. Details of the group's sufferings and final days were published widely and read eagerly as an account of Christian pilgrimage and exaltation. Comparisons with the fate of other British missionaries worldwide, with Franklin (now presumed dead), and even with military figures like General Gordon, gathered Gardiner and his companions into an imperial pantheon. Scurvy played a complex and intriguing role in this process of apotheosis. [ABSTRACT FROM PUBLISHER]

Abstract: The fjord landscape of South America, stretching ~1500 km between Golfo Corcovado (~43°S) and Tierra del Fuego (~56°S), is the largest continuous fjord landscape on Earth. This paper presents the results of new structural geological and geomorphological mapping of this landscape using optical satellite images and digital elevation models. First-order geological structures are represented by strike-slip faults forming lineaments up to hundreds of kilometres long. The strike-slip faulting has been active since Late Cretaceous times and is responsible for the presence of a conspicuous structural cleavage visible as lineaments up to ~10 km long. A detailed analysis of these second-order lineaments from digital image data was carried out in three sectors. In Sector 1, located northwest of the North Patagonian Icefield, there are three distinct mean orientations, characterized by a main nearly orogen-parallel orientation (az. ~145°) and two orogen-oblique secondary orientations (az. ~20° and az. ~65°). In Sector 2, located west of the South Patagonian Icefield, there are also three separate mean orientations, with most of the lineaments concentrated between azimuths 0° and 80° (mean at ~36°); and two other orogen-oblique means at azimuth ~122° and ~163°. In Sector 3, around the Cordillera Darwin, there is a single main orogen-parallel mean at ~100–115°. In all three sectors, mapped fjord orientations bear a striking similarity to the structural data, with fjords orientated preferentially in the same direction as structural lineaments. We infer that successive glaciations followed the same ice-discharge routes, widening and deepening pre-existing geological structures at the expense of the surrounding terrain to create the fjord landscape. This study has broader implications for ice sheet reconstructions and landscape evolution beneath ice sheets because we demonstrate that the primary control on fjord development in glaciated areas is geological and not glaciological. [Copyright &y& Elsevier]