The principal objective of the IsoTroph project is to improve the geochemical method used in the paleontology of terrestrial mammals in detection of their trophic position. In particular, the project focuses on a difference in δ15N between single amino acids (glutamate and phenylalanine) that is then used to calculate the trophic discrimination factor (TDF). It is a quantitative parameter used in reconstructions of past animal or human trophic levels (a primary consumer level – a herbivore; a secondary consumer level – a carnivore feeding on herbivores; etc.), crucial for understanding the evolution of environments. The TDF has never been established before for terrestrial mammals, although it is a key parameter in modeling past ecology.
The main research method of the IsoTroph is the analysis of δ15N in selected amino acids in bone collagen of a predator's population and that of its prey. These results are then calculated into the TDF between these populations. To achieve this, the project will involve a study of modern populations (collections of recent bones of wolf, lynx, red fox, and their prey) and a collection of fossils from a Pleistocene carnivore den (cave hyena and its prey). These collections will provide insight into four species of mammalian carnivores, representing variable ecology (both hypercarnivores and omnivores) and different chronologies (recent and Pleistocene).
Department of Geosciences and Geography
00014 University of Helsinki
Office: AG Biogeologie, Room S523
Hölderlinstrasse 12, D-72070 Tübingen
+49 (0) 7071 29-78900
Publications of the project
Bocherens H. and Drucker D. 2003. Trophic level isotopic enrichment of carbon and nitrogen in bone collagen: case studies from recent and ancient terrestrial ecosystems International Journal of Osteoarchaeology 13: 46-53. doi.org/10.1002/oa.662
Chikaraishi Y., Ogawa N.O., Doi,H. et al. 2011. 15N/14N ratios of amino acids as a tool for studying terrestrial food webs: a case study of terrestrial insects (bees, wasps, and hornets). Ecol Res 26: 835–844. doi.org/10.1007/s11284-011-0844-1
Krajcarz M., Krajcarz M.T. 2014. The red fox (Vulpes vulpes) as an accumulator of bones in cave-like environments. International Journal of Osteoarchaeology 24: 459-475. doi.org/10.1002/oa.2233
Ohkouchi N., Chikaraishi Y., Close H.G. et al. 2017 Advances in the application of amino acid nitrogen isotopic analysis in ecological and biogeochemical studies. Organic Geochemistry 113: 150-174. doi.org/10.1016/j.orggeochem.2017.07.009.
Krajcarz M.T., Krajcarz M., Bocherens H. 2018. Collagen-to-collagen prey-predator isotopic enrichment (Δ13C, Δ15N) in terrestrial mammals – a case study of a subfossil red fox den. Palaeogeography, Palaeoclimatology, Palaeoecology 490: 563–570. doi.org/10.1016/j.palaeo.2017.11.044
O'Connell TC. 2017 'Trophic' and 'source' amino acids in trophic estimation: a likely metabolic explanation. Oecologia 184 (2):317-326. doi.org/10.1007/s00442-017-3881-9
Krajcarz M.T., Krajcarz M., Drucker D.G., Bocherens H. 2019. Prey‐to‐fox isotopic enrichment of 34S in bone collagen: Implications for paleoecological studies. Rapid Communications in Mass Spectrometry 33: 1311–1317. doi.org/10.1002/rcm.8471
Naito Y.I., Meleg I.N., Robu M. et al. 2020. Heavy reliance on plants for Romanian cave bears evidenced by amino acid nitrogen isotope analysis. Scientific Reports 10: 6612. doi.org/10.1038/s41598-020-62990-0
Project funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 101023317