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Show AN INDIVIDUAL MIGRATION STORY: COMPARING STRONTIUM ISOTOPE ANALYSIS IN ENAMEL, IVORY, AND FOOD SOURCES FROM A SINGLE MODERN ELEPHANT Katya Deming 1School 1,2 Podkovyroff 2 Yang , Gabriel (Faculty Mentor: Diego 2 Bowen , Kevin 2,3,4 Uno , Nancy 5 Carpenter , 2 Fernandez ), and Thure 1,2 Cerling of Biological Sciences, University of Utah, 2Department of Geology and Geophysics, University of Utah, 3Columbia University Lamont-Doherty Earth Observatory Division of Biology and Paleo Environment, 4Harvard University Department of Human Evolutionary Biology, 5Utah’s Hogle Zoo ABSTRACT Focusing on strontium (Sr) isotope analysis, this project directly contributed to the collection, processing and data configuration of elephant ivory and molar samples as well as food eaten by said elephant. Misha, an elephant from the Salt Lake City Hogle Zoo, had previously been living in California and then was moved to Utah. To follow this migration, ivory, enamel, and food samples were analyzed to determine Sr isotopic composition. This data encapsulates the complexity and abilities in stable isotope analysis for migration research. MATERIALS AND METHODS Sample Collection • Ivory: The ivory samples were collected using a micromilling device from Ivory piece #889. Four sets of samples were collected, identified as the 300s and 400s-600s series. • Enamel: The molar samples were already collected with a distinction of two techniques: C4 (micromill from Misha Rm3.5b enamel) vs C6 (conventionally sampled from Misha_Rm3.5 enamel). • Food: Food was provided in paper envelopes and labeled with contents. RESULTS: LASER ABLATION OF TUSK DENTIN Digestion: • • Fig. 6: Previous Laser Ablation Sr isotope profile Enamel and Ivory: Powered samples were dissolved in concentrated nitric acid (HNO3) with the enamel samples be filled to the same value amount with MilliQ water. Enamel 1 Run (next to EDJ) 0.714 Food: All samples were incinerated at 550 ºC and then ashes were digested with 2-3 mL of HNO3. 0.712 Elemental Analysis of Trace and Major Elements (Ivory, Enamel and Food) • Fields of archaeology and geochemistry have used stable isotope analysis processes have been used as evidence for topics such as human evolution, migration research, transitions to agriculture, among other topics1,2 • Mammalian tooth enamel forms incrementally from the top to the base of the tooth, allowing change through time to be tracked isotopically (Fig. 1) • 87Sr/86Sr reflects the bedrock Sr that is made available in soils to plants analysis and can be used to reconstruct migration during tooth mineralization • Bioavailable Sr is affected by the extent and type of weathering that occurs from the bedrock to soil which can be ultimately detected in the enamel or ivory samples of organisms2 • Isotopic variations of tooth enamel or ivory can be used to create isoscapes of geographic regions as well as further studied to analyze variations in migration patterns, climate and diet as a means of further understanding archaeological questions as well as modern mammals4,6,9 A calibration curve was prepared from single-element standards (Inorganic Ventures, Christianburg, VA, US), with indium added as internal standard. • 0.708 0.706 0.704 1200 Diluted samples and calibration solutions were run in a triple quadrupole inductively coupled plasma mass spectrometer (ICPMS, Agilent 8900, Santa Clara, California, USA). 1400 1600 1800 2000 2200 Certified reference materials 1643f (Trace Elements in Water, National Institute of Standards and Technology, Gaithersburg, MD, US) was used as a control for data quality. • • Using the Sr concentration calculated from the elemental analysis, aliquots containing 200 ng of Sr in 2 M HNO3 (prepared by mixing sample digest + conc HNO3 + water) and run through an automated Srpurification system (PrepFAST, ESI, Omaha, NE, US). Purified Sr fractions, contained in 6 M HNO3, were then dried down at 185 °C and redissolved with 1mL of 2.4% HNO3. These Sr fractions were used for isotopic analysis in a multicollector ICPMS (Neptune, ThermoFinnigan, Breman, Germany). 2800 3000 3200 Enamel 3 Run: 87Sr/86Sr vs. Cycle 0.714 0.712 0.712 87Sr/86Sr Sr Purification and 87Sr/86Sr determination (Ivory, Enamel and Food) 2600 Enamel 2 Run: 87Sr/86Sr vs. Cycle 0.714 • 2400 Cycle 0.710 0.710 0.708 0.708 0.706 0.706 0.704 0.704 100 600 1100 1600 150 2100 650 1150 1650 2150 Cycle Cycle Enamel 5 Run: 87Sr/86Sr vs Cycle 0.714 0.712 • Certified reference material 987 (SrCO3, National Institute of Standards and Technology, Gaithersburg, MD, US) was used to monitor the accuracy of the method. High-resolution laser-ablation Sr analysis (Ivory) 87Sr/86Sr • An ivory tusk is a modified upper incisor that forms incrementally throughout the lifetime of an elephant both in length and girth • 87Sr/86Sr • Stable isotope analysis of tooth enamel, bone, and ivory has emerged as a powerful tool for migration research of living and fossil animals5,8,9 All samples were diluted by a factor of 50 directly into an autosampler plate. 87Sr/86Sr BACKGROUND • 0.710 0.710 0.708 0.706 • Using a 193 nm excimer laser (Teledyne Excite) ~30 mm scans with 100 um diameter laser spot were run along the enamel-dentine junction. A marine shell was used as accuracy check, with measured values 0.70920 plus minus 0.00006. RESULTS: DISSOLUTION METHOD OF IVORY, ENAMEL AND FOOD 0.704 100 600 1100 1600 2100 Cycle Fig. 7: Laser Ablation Sr isotope profile from Misha molar Rm3.5b DISCUSSION AND CONCLUSIONS • Confirmation of the previous results completed by Dr. Kevin Uno, former PhD student • Both the enamel analyses line up with one another as well as conceptually Fig. 1: Example of a bovid tooth serially sampled for isotopic analysis, with sampling lines in red7 • The value of having food data is to get an idea of how food intake can play a role in Sr isotope analysis, not just for carbon isotopes. Fig. 3: Micromill Sr isotope profile data from Misha Ivory piece #889 • The final product of this project will result in a comprehensive modeling of Sr turnover, the time it takes for an animal to switch values in Sr based on movement, which will be a major contribution to paleodiet research. REFERENCES 1. Cerling, T. E., Andanje, S. A., Blumenthal, S. A., Brown, F. H., Chritz, K. L., Harris, J. M., Hart, J. A., Kirera, F. M., Kaleme, P., Leakey, L. N., Leakey, M. G., Levin, N. E., Manthi, F. K., Passey, B. H., & Uno, K. T. (2015). Dietary changes of large herbivores in the Turkana Basin, Kenya from 4 to 1 Ma. Proceedings of the National Academy of Sciences, 112(37), 11467-11472. 2. Coutu AN, Lee-Thorp J, Collins MJ, Lane PJ. Mapping the Elephants of the 19th Century East African Ivory Trade with a Multi-Isotope Approach. PLoS One. 2016 Oct 19;11(10):e0163606. doi: 10.1371/journal.pone.0163606. PMID: 27760152; PMCID: PMC5070863 • In order to correct for mixing ratios of the food, an intake model has been to be made to evaluate how much Sr intake is being consumed by those food items (Deming Yang) Fig. 4: Sr isotope profile from C6 vs C4 Misha enamel 3. Higgins, P., & MacFadden, B. J. (2004). “Amount Effect” recorded in oxygen isotopes of Late Glacial horse (Equus) and bison (Bison) teeth from the Sonoran and Chihuahuan deserts, southwestern United States Palaeogeogr. Palaeoclimatol. Palaeoecol., 206 (3–4) (2004), pp. 337-353. https://doi.org/10.1016/j.palaeo.2004.01.011 4. Koch, P.L., Fisher, D. C., & Dettman, D (1989). Oxygen isotope variation in the tusks of extinct proboscideans: A measure of season of death and seasonality. Geology 1989;; 17 (6): 515–519. https://doi.org/10.1130/0091-7613(1989)017<0515:OIVITT>2.3.CO;2 • Completing a multiple tissue, multiple method analysis of an animal that is relatively controlled as well as having data on the food the animal consumed can immensely assist in how to complete paleontology migration research in the future. 5. Lazzerini, N., Balter, V., Coulon, A., Tacail, T., Marchina, C., Lemoine, M., Bayarkhuu, N., Turbat, Ts., Lepetz, S., & Zazzo, A. (2021). Monthly mobility inferred from isoscapes and laser ablation strontium isotope ratios in caprine tooth enamel. Scientific Reports, 11(1), 111. 6. O’Brien, K. (2021) “Example of serial sampling on a bovid molar, with sampling locations in red.” Doctoral Dissertation Proposal. 7. Reade, H., Stevens, R. E., Barker, G., & O'Connell, T. C. (2015). Tooth enamel sampling strategies for stable isotope analysis: Potential problems in cross-method data comparisons. Chemical Geology, Volume 404, pp. 126-135. https://doi.org/10.1016/j.chemgeo.2015.03.026. 8. Wang, Y., & Cerling, T. E. (1994). A model of fossil tooth and bone diagenesis: Implications for paleodiet reconstruction from stable isotopes. Palaeogeography, Palaeoclimatology, Palaeoecology, 107(3-4), 281–289. https://doi.org/10.1016/0031-0182(94)90100-7 ACKNOWLEDGMENTS Fig. 5: Sr isotope profile from Hogle Zoo food This project was completed as a senior thesis in the Department of Geology and Geophysics at the University of Utah, with funding from the College of Mines and Earth Sciences Barbara Nash Research & Development fund for equipment usage. We also thank Deming Yang 1, Gabriel J. Bowen, Kevin T. Uno, Nancy A. Carpenter, and Thure E. Cerling for their collaboration on this project. |
