Reconstruction of the late quaternary glacial geology on King George Island, South Shetland Islands: First steps of a geoscientific project

King George Island (Isla 25 de Mayo) is the largest one of the South Shetland Islands (SShI). This archipelago is located approximately 120 km NW of the Antarctic Peninsula, from which it is separated by the Bransfield Strait (Mar de la Flota). The SShI are located just south of the Antarctic Convergence Zone in a key location for investigating glacial and climatic fluctuations relative to both the Southern Hemisphere and the rest of Antarctica. The geomorphology and glacier geology of the SShI (Sugden and John 1973, Hall 2003 and 2007, Del Valle et al. 2007, Strelin 2010, Simms et al. 2011) constitutes a fragmentary record. Despite the deglaciation, inland ice free areas are scarce and are strongly affected by the thaw with the consequent destruction of previous geoforms. The few obtained radiocarbon ages on land exposures have poor stratigraphic control being necessary to consider the problems of pollution and the reservoir effect that affect them. Based on geochemical and sedimentological proxies and radiocarbon dating in sedimentary cores obtained from bays, some glaciers advances and warm periods have been inferred for the middle and late Holocene, among them are those corresponding to the Medieval Climate Optimum and the Little Ice Age (LIA) (Yoon et al. 2000 and 2004, Hass et al. 2010, Monien et al. 2011). It should be noted that for some glaciological reconstructions based on organic radiocarbon dating on marine sediments the ages are still questionable. Often it does not exist yet a clear criteria of correlation that allow to link between glaciterrestrial sediments and glacimarine ones. The study of the glacial, periglacial and coastal marine record of King George Island has a particular importance to enhance the knowledge of its paleoenvironmental evolution since the Marine Isotopic Stage 3 (MIS 3). There is no precision on the beginning and end of the Last Glacial Maximum (LGM), nor on the rhythm of the deglaciation post-LGM, known as Termination 1, both for coastal and marine areas, as well as offshore areas from King George Island. In the same way, it´s not known if there was a glacial advance linked with the Antarctic Cold Reversal clearly detectable in Antarctic ice cores or sediment deposits in southern Patagonian exposures (Strelin et al. this congress). The way in which the deglaciation continued during the early Holocene, the peak of the Holocene marine transgression (Strelin et al. this Congress), the later chronology of the Neoglacial advances, including the LIA, and the warmer periods that separate them are as well topics to deepen. The objective of this project is to study and date the geomorphological and glaciterrestrial evidences linked to the glacial history in the area of South Shetland Islands, since MIS 3, correlate them with bathymetric records and proxies from marine cores and discuss its link with other sectors of the Antarctic Peninsula, particularly with James Ross Islan

Exploring the ontogenetic scaling hypothesis during the diversification of pollination syndromes in <i>Caiophora</i> (Loasaceae, subfam. Loasoideae)

Phenotypic diversification of flowers is frequently attributed to selection by different functional groups of pollinators. During optimization of floral phenotype, developmental robustness to genetic and non-genetic perturbations is expected to limit the phenotypic space available for future evolutionary changes. Although adaptive divergence can occur without altering the basic developmental programme of the flower (ontogenetic scaling hypothesis), the rarity of reversion to ancestral states following adaptive radiations of pollination syndromes suggests that changes in the ancestral developmental programme of the flower are common during such evolutionary transitions. Evidence suggests that flower diversification into different pollination syndromes in the Loasoideae genus Caiophora took place during a recent adaptive radiation in the central Andes. This involved transitions from bee to hummingbird and small rodent pollination. The aim of this work was to examine if the adaptive radiation of pollination syndromes in Caiophora occurred through ontogenetic scaling or involved a departure from the ontogenetic pattern basal to this genus.Fil: Strelin, Marina Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Benitez-Vieyra, Santiago Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Fornoni, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina. Universidad Nacional Autónoma de México; MéxicoFil: Klingenberg, Christian Peter. University of Manchester; Reino UnidoFil: Cocucci, Andrea Aristides. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin

A case of behavioural diversification in male floral function – the evolution of thigmonastic pollen presentation

The authors gratefully acknowledge funding provided by an Else-Neumann-Stipendium (http://www.fu-berlin.de/sites/promovieren/drs/nachwuchs/nachwuchs/nafoeg.html), Deutscher Akademischer Austausch Dienst (DAAD) and botconsult GmbH at different stages of data acquisition. We thank Tobias Grass, Joana Bergmann and Franziska Weber (Freie Universität Berlin) for help with data collection in the field and in the greenhouse. Nicole Schmandt, Federico Luebert, Juliana Chacón and Dietmar Quant (Universität Bonn) provided help in the molecular laboratory and the edition of the molecular dataset. We furthermore thank Markus Ackermann (Koblenz) for providing photographs, Philipp Klein (Berlin) for editing the video and Katy Jones (Berlin) for helpful comments on an earlier version of the manuscript. Rafael Acuña has been supported by the ALECOSTA scholarship program. Coverage of the article processing charge by the German Research Foundation via the Open Access Publication Fund of the Freie Universität Berlin is gratefully acknowledged.Peer reviewedPublisher PD

The impact of Holocene deglaciation and glacial dynamics on the landscapes and geomorphology of Potter Peninsula, King George Island (Isla 25 Mayo), NW Antarctic Peninsula

The timing and impact of deglaciation and Holocene readvances on the terrestrial continental margins of the Antarctic Peninsula (AP) have been well-studied but are still debated. Potter Peninsula on King George Island (KGI) (Isla 25 de Mayo), South Shetland Islands (SSI), NW Antarctic Peninsula, has a detailed assemblage of glacial landforms and stratigraphic exposures for constraining deglacial landscape development and glacier readvances. We undertook new morphostratigraphic mapping of the deglaciated foreland of the Warszawa Icefield, an outlet of the Bellingshausen (Collins) Ice Cap on Potter Peninsula, using satellite imagery and new lithofacies recognition and interpretations, combined with new chronostratigraphic analysis of stratigraphic sections, lake sediments, and moraine deposits. Results show that the deglaciation on Potter Peninsula began before c. 8.2 ka. Around c. 7.0 ka, the Warszawa Icefield and the marine-facing Fourcade Glacier readvanced across Potter Peninsula and to the outer part of Potter Cove. Evidence of further readvances on Potter Peninsula was absent until the Warszawa Icefield margin was landward of its present position on three occasions: c. 1.7–1.4 ka, after c. 0.7 ka (most likely c. 0.5–0.1 ka), and by 1956 CE. The timing of Holocene deglaciation and glacier fluctuations on Potter Peninsula are broadly coeval with other glacier- and ice-free areas on the SSI and the northern AP and likely driven by interactions between millennial–centennial-scale changes in solar insolation and irradiance, the southern westerlies, and the Southern Annular Mode