| Summary: | During the Last Glacial Maximum (LGM), the Antarctic ice sheets expanded onto the continental shelf and thickened to several hundred meters above the present sea level in coastal areas. As a result, Adélie Penguins (Pygoscelis adeliae) were pushed out from their ancestral colonies and settled in ice-free coastal areas. Along the Victoria Land coast we found evidence of penguins colonization predating the LGM, well preserved below glacially deformed marine deposits and thin glacial drift. After the deglaciation, Adélie Penguins recolonized their ancestral nesting sites on newly released ice-free coastal terrains. Almost half the estimated world population of Adélie penguins (about 5 million individuals) breed in the Ross Sea where, at present, some 40 colonies are found. An accurate geomorphological survey of ice-free areas allowed us to discover tens of Holocene relict colonies, identified in areas where the Adélies do not nest at present. Penguin material is preserved in ornithogenic soils below abandoned nesting sites, where we found organic material formed by the accumulation of penguin guano, as well as bone, skin, feathers and eggshells. Datable penguin organic remains recovered from ornithogenic soils through stratigraphic excavation have been used to reconstruct a chronology of penguin occupation during Late Pleistocene and Holocene periods. For their excellent preservation, penguin remains from ornithogenic soils have proven a powerful tool in multiple areas of research. The isotopic record of Adélie penguin remains (eggs and guano) supply new insights into the past feeding penguin behaviour and, on a larger scale, about the paleoecological conditions of Antarctica. Finally, ancient DNA sequences of Adélie penguin’s bones supply new insights for estimating any genetic responses to Antarctic environmental changes during the past > 30,000 yrs. This allowed us to better define the evolutionary trends of Adélie penguin and the Holocene climatic and environmental background.
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