Thuan H Chau1, Brett J Tipple1,2, Lihai Hu3, Diego P Fernandez3, Thure E Cerling1,2,3, James R Ehleringer1,2, Lesley A Chesson1. 1. IsoForensics, Inc., 421 Wakara Way, Suite 100, Salt Lake City, UT, 84108, USA. 2. Department of Biology, University of Utah, 257 S 1400 E, Salt Lake City, UT, 84112, USA. 3. Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT, 84112, USA.
Abstract
RATIONALE: Oxygen isotope ratios (δ18 O values) of hair largely reflect features of regional hydrology while strontium isotope ratios (87 Sr/86 Sr) are thought to reflect bedrock geology; combination of both isotope signatures may provide greater capacity for determining provenance and reconstructing travel history of an organism. To test this hypothesis, we compared the O-Sr isotope profiles of hair from domestic horses with known residency histories. METHODS: Tail hairs were collected from a pair of horses pastured together for a period of 16 months, one of which lived in a different location for the 8 months prior. Hair samples were washed with solvents to remove external contaminants prior to sequential sampling for δ18 O and 87 Sr/86 Sr analysis via TC/EA-IRMS and MC-ICP-MS, respectively. Hair digests were concentrated and analyzed employing low-flow natural aspiration to measure 87 Sr/86 Sr. RESULTS: Tail hair from the control and transported horses had mean δ18 O values of 11.25 ± 1.62 ‰ and 10.96 ± 1.53 ‰, and mean 87 Sr/86 Sr of 0.7101 ± 0.0006 and 0.7109 ± 0.0020, respectively. The δ18 O and 87 Sr/86 Sr profiles for the control and transported horses were indistinguishable when they were pastured together. The 87 Sr/86 Sr profiles were significantly different during the period that the horses were living apart, while the δ18 O values were indistinguishable during that period. CONCLUSIONS: By comparing the O-Sr isotope profiles of a control and transported horse, we investigated isotopic signal(s) potentially useful for reconstructing travel histories via high-resolution sequential sampling along single strands of tail hair. Improved analytical capabilities allowed for extremely low Sr abundance samples to be analyzed for 87 Sr/86 Sr and proved capable of resolving a horse's movement between distinct regions.
RATIONALE: Oxygen isotope ratios (δ18 O values) of hair largely reflect features of regional hydrology while strontium isotope ratios (87 Sr/86 Sr) are thought to reflect bedrock geology; combination of both isotope signatures may provide greater capacity for determining provenance and reconstructing travel history of an organism. To test this hypothesis, we compared the O-Sr isotope profiles of hair from domestic horses with known residency histories. METHODS: Tail hairs were collected from a pair of horses pastured together for a period of 16 months, one of which lived in a different location for the 8 months prior. Hair samples were washed with solvents to remove external contaminants prior to sequential sampling for δ18 O and 87 Sr/86 Sr analysis via TC/EA-IRMS and MC-ICP-MS, respectively. Hair digests were concentrated and analyzed employing low-flow natural aspiration to measure 87 Sr/86 Sr. RESULTS: Tail hair from the control and transported horses had mean δ18 O values of 11.25 ± 1.62 ‰ and 10.96 ± 1.53 ‰, and mean 87 Sr/86 Sr of 0.7101 ± 0.0006 and 0.7109 ± 0.0020, respectively. The δ18 O and 87 Sr/86 Sr profiles for the control and transported horses were indistinguishable when they were pastured together. The 87 Sr/86 Sr profiles were significantly different during the period that the horses were living apart, while the δ18 O values were indistinguishable during that period. CONCLUSIONS: By comparing the O-Sr isotope profiles of a control and transported horse, we investigated isotopic signal(s) potentially useful for reconstructing travel histories via high-resolution sequential sampling along single strands of tail hair. Improved analytical capabilities allowed for extremely low Sr abundance samples to be analyzed for 87 Sr/86 Sr and proved capable of resolving a horse's movement between distinct regions.
Authors: Lesley A Chesson; Janet E Barnette; Gabriel J Bowen; J Renée Brooks; John F Casale; Thure E Cerling; Craig S Cook; Charles B Douthitt; John D Howa; Janet M Hurley; Helen W Kreuzer; Michael J Lott; Luiz A Martinelli; Shannon P O'Grady; David W Podlesak; Brett J Tipple; Luciano O Valenzuela; Jason B West Journal: Oecologia Date: 2018-06-28 Impact factor: 3.225