Recruitment for the position of Scholarship Holder/PhD Student in the field of stable isotope biogeochemistry at the Institute of Geological Sciences, Polish Academy of Sciences, in Warsaw

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Recruitment for the position of Scholarship Holder/PhD Student in the field of stable isotope biogeochemistry at the Institute of Geological Sciences, Polish Academy of Sciences, in Warsaw Sintesi in italiano (traduzione automatica): L'Istituto di Scienze Geologiche dell'Accademia Polacca delle Scienze a Varsavia è alla ricerca di un borsista/Studente di Dottorato nel campo della biogeochimica degli isotopi stabili. Il progetto si concentra sull'analisi delle variazioni degli isotopi stabili (δ 13C e δ 15N) in ecosistemi terrestri temperati, con particolare attenzione a piante e erbivori. Le mansioni principali includono l'analisi di campioni moderni e fossili per comprendere le relazioni trofiche e la variabilità isotopica. È richiesta una laurea in Scienze Ambientali, Biologia o un campo correlato. Il candidato ideale avrà competenze in analisi isotopiche e un forte interesse per la paleoecologia. PROJECT SUMMARY: The general objective of the project is to recognize the patterns of variability of the stable isotope ( δ 13C and δ 15N) baselines for protein fraction in terrestrial temperate ecosystems: in plants and mammalian herbivores. In particular, the project main focus is checking if more-than-one isotopic baselines may occur within a community (of plants, or of mammalian herbivores) in an ecosystem. Our preliminary data suggests that this may be the case. If this hypothesis will be confirmed, it would mean that several independent baselines should be included in the isotope flux models, even for a single ecosystem. The geological actualism approach in this project is to check: which exactly modern subcommunities of forest plants and herbivores have distinctly different baselines (subcommunities that differ in phylogeny, habitat, physiology?), if any; and whether such situation of multiple variable baselines is common in micro-ecosystems (e.g., dense canopy vs. open environment, conifer vs. deciduous forest?). The ultimate goal is to use these patterns of the modern isotopic variability in plants, herbivores, and plants-to-herbivores system, to better interpret the isotope flux in fossil assemblages, with the focus on bone collagen – usually the only organic material preserved in fossils. We focus on terrestrial temperate ecosystems, because such ecosystems are common in European Quaternary record (especially forest and mammoth steppe) and are among the majority of paleoecosystems studied in Europe, North America, Siberia, Beringia, and Patagonia. We focus on modern and fossil ecosystems from Poland: modern temperate forest (the Białowieża Forest), Early-to-Late Holocene forest paleontological assemblages (Perspektywiczna Cave, Shelter in Smoleń III); and mid-Vistulian mammoth steppe assemblage (Perspektywiczna Cave). A Late Glacial tundra assemblage (Perspektywiczna Cave) will be added for comparison. The project methods are analyses of carbon and nitrogen stable isotopes in plants (protein, cellulose, lignin) and herbivores (bone collagen) material. Modern material (Białowieża Forest) will be used to refine the methodology: establishing the variability in plants and in herbivores; understanding the plant-to-collagen isotope fractionation; and to depict the complexity of the carbon and nitrogen isotopic flux within a plant-to-herbivore trophic network, where the Białowieża Forest is an actualistic model. Fossil material (from cave sites located in Polish Jura) of the Holocene forest ecosystem will be used to compare the fossil isotopic baselines with the modern ones and to test for the universality of the baseline variability among temperate forest ecosystems. Pleistocene assemblages (Perspektywiczna Cave) will be used to check the variability of the isotopic baselines in other ecosystems (mammoth steppe and tundra). We will further use the C-N flux model obtained for the modern ecosystem to better interpret the trophic relationships in fossil assemblages. Among novel approaches is the individual amino acid isotopic analysis for terrestrial paleoecosystems. Until now, only few studies have undertaken this topic, mostly from the archaeological perspective. Other novel approaches include: searching for seasonal isotopic changes in plants; investigation of the local Suess effect through tree rings study; systematic analysis of the isotopic variation between ungulates, rodents and lagomorphs; assumption of several isotopic baselines within one ecosystem. Isotopic baselines are necessary for stable isotope-based paleodietary modeling. In particular, the knowledge of the baseline variability is crucial at the planning phase of studies – to assume how much baseline samples is needed and what taxonomic variability is enough to represent baselines. In Quaternary sciences, such studies are common in paleoecology, with special focus on ancient hominines, extinct mammals, and the evolution of synanthropism. All such studies wi Annuncio in inglese. Fonte: Euraxess (Commissione europea).