2.1 Sampling
We live-captured all mice using Sherman live traps and other methods described in Storz et al., (2020, 2024). We collected mice from a broad range of elevations in the Altiplano/Puna de Atacama ecoregions, from 2,340 m in the Atacama Desert to the 6,739 m summit of Volcán Llullaillaco (Figure 1). We sacrificed mice in the field, prepared them as museum specimens, and preserved liver tissue in 95‰ ethanol as source material for the stable isotope analysis. For the P. vaccarum specimen captured on the summit of Volcán Llullaillaco, we preserved the entire gastrointestinal tract in ethanol as a source of DNA for metagenomic and metabarcoding analyses. All mouse specimens are housed in the Colección de Mamíferos of the Universidad Austral de Chile, Valdivia, Chile.
We collected all mice in accordance with permissions to JFS and GD from the following Chilean government agencies: Servicio Agrícola y Ganadero (SAG, Resolución exenta # 6633/2020), Corporación Nacional Forestal (CONAF, Autorización # 171219), and Dirección Nacional de Fronteras y Límites del Estado (DIFROL, Autorización de Expedición Científica #68/2020). We handled all mice in accordance with protocols approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Nebraska (project ID: 1919).