title: Experimental evidence shows no fractionation of strontium isotopes ((87)Sr/(86)Sr) among soil, plants, and herbivores: implications for tracking wildlife and forensic science.
abstract: Strontium isotopes ((87)Sr/(86)Sr) can be useful biological markers for a wide range of forensic science applications, including wildlife tracking. However, one of the main advantages of using (87)Sr/(86)Sr values, that there is no fractionation from geological bedrock sources through the food web, also happens to be a critical assumption that has never been tested experimentally. We test this assumption by measuring (87)Sr/(86)Sr values across three trophic levels in a controlled greenhouse experiment. Adult monarch butterflies were raised on obligate larval host milkweed plants that were, in turn, grown on seven different soil types collected across Canada. We found no significant differences between (87)Sr/(86)Sr values in leachable Sr from soil minerals, organic soil, milkweed leaves, and monarch butterfly wings. Our results suggest that strontium isoscapes developed from (87)Sr/(86)Sr values in bedrock or soil may serve as a reliable biological marker in forensic science for a range of taxa and across large geographic areas.
authors: a Department of Integrative Biology , University of Guelph , Guelph , Ontario , Canada.
authors: D T Tyler
authors: DT
authors: Flockhart
authors: T Kurt
authors: TK
authors: Kyser
authors: Don
authors: D
authors: Chipley
authors: Nathan G
authors: NG
authors: Miller
authors: D Ryan
authors: DR
authors: Norris
mesh_terms: D000818:Animals; D031108:Asclepias / Q000378:metabolism*; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D002080:Butterflies / Q000378:metabolism; D002170:Canada; D004784:Environmental Monitoring / Q000379:methods*; D020387:Food Chain; D060434:Herbivory; D016014:Linear Models; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism*; D013324:Strontium / Q000032:analysis / Q000378:metabolism*; D013325:Strontium Isotopes / Q000032:analysis; D014921:Wings, Animal / Q000737:chemistry
chemical_list: D015415:Biomarkers; D012989:Soil Pollutants; D013325:Strontium Isotopes; D013324:Strontium
keywords: Danaus plexippus; geographic assignment; isoscape; isotope ecology; migration; migratory connectivity; monarch butterfly; plant; soil; strontium-86; strontium-87