title: Reconstruction of travel history using coupled δ18O and87Sr/86Sr measurements of hair.
abstract: BACKGROUND
  Oxygen isotope ratios (δ18O values) of hair largely reflect features of regional hydrology while strontium isotope ratios (87Sr/86Sr) 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 δ18O and87Sr/86Sr analysis via TC/EA-IRMS and MC-ICP-MS, respectively. Hair digests were concentrated and analyzed employing low-flow natural aspiration to measure87Sr/86Sr.
  
  
  RESULTS
  Tail hair from the control and transported horses had mean δ18O values of 11.25 ± 1.62 ‰ and 10.96 ± 1.53 ‰, and mean87Sr/86Sr of 0.7101 ± 0.0006 and 0.7109 ± 0.0020, respectively. The δ18O and87Sr/86Sr profiles for the control and transported horses were indistinguishable when they were pastured together. The87Sr/86Sr profiles were significantly different during the period that the horses were living apart, while the δ18O 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 for87Sr/86Sr and proved capable of resolving a horse's movement between distinct regions. Copyright © 2017 John Wiley & Sons, Ltd.
authors.affiliation: IsoForensics, Inc., 421 Wakara Way, Suite 100, Salt Lake City, UT, 84108, USA.
authors.forename: Thuan H
authors.identifier: http://orcid.org/0000-0003-0390-4921
authors.initials: TH
authors.lastname: Chau
authors.affiliation: IsoForensics, Inc., 421 Wakara Way, Suite 100, Salt Lake City, UT, 84108, USA.|Department of Biology, University of Utah, 257 S 1400 E, Salt Lake City, UT, 84112, USA.
authors.forename: Brett J
authors.initials: BJ
authors.lastname: Tipple
authors.affiliation: Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT, 84112, USA.
authors.forename: Lihai
authors.identifier: http://orcid.org/0000-0003-2044-0524
authors.initials: L
authors.lastname: Hu
authors.affiliation: Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT, 84112, USA.
authors.forename: Diego P
authors.initials: DP
authors.lastname: Fernandez
authors.affiliation: IsoForensics, Inc., 421 Wakara Way, Suite 100, Salt Lake City, UT, 84108, USA.|Department of Biology, University of Utah, 257 S 1400 E, Salt Lake City, UT, 84112, USA.|Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT, 84112, USA.
authors.forename: Thure E
authors.initials: TE
authors.lastname: Cerling
authors.affiliation: IsoForensics, Inc., 421 Wakara Way, Suite 100, Salt Lake City, UT, 84108, USA.|Department of Biology, University of Utah, 257 S 1400 E, Salt Lake City, UT, 84112, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Ehleringer
authors.affiliation: IsoForensics, Inc., 421 Wakara Way, Suite 100, Salt Lake City, UT, 84108, USA.
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Chesson
mesh_terms: D000818:Animals; D002247:Carbon Isotopes / Q000032:analysis; D006197:Hair / Q000737:chemistry*; D006736:Horses; D013058:Mass Spectrometry / Q000379:methods*; D010103:Oxygen Isotopes / Q000032:analysis*; D013325:Strontium Isotopes / Q000032:analysis*; D014195:Travel
chemical_list: D002247:Carbon Isotopes; D010103:Oxygen Isotopes; D013325:Strontium Isotopes