Proteomic analysis resulting in species‐level identification of recently diverged North American arvicoline rodents

ABSTRACT North American arvicoline rodents have long been considered to have high biogeographic, biochronologic, and paleoecological value. They provide relative dating of faunal assemblages when absolute dating is not possible and contribute to paleobiome characterization. However, the scientific value of Arvicolinae is often limited by the level of taxonomic identification achievable by morphological analyses. ZooMS (zooarchaeology by mass spectrometry) is a proteomic method that permits taxonomic identification of bone material. We added 19 North American arvicoline species to the ZooMS reference database to assess the level of taxonomic resolution between those species using ZooMS. Results show species‐level taxonomic resolution for all tested arvicolines that diverged up to just under 1 mya. We estimate species‐level taxonomic resolution is achievable for arvicolines that diverged up to 273 kya and up to 170.5 kya for members of Microtus . Application to arvicoline fossils demonstrates the presence of previously unidentified species of Microtus in the Great Basin, that isolated molars are sufficient for taxonomic identification, and provides results consistent with the morphological hypothesis that Microtus paroperarius and Alexandromys oeconomus are not conspecific. ZooMS can drastically improve taxonomic identification of arvicolines, and may increase their utility for biochronological, biogeographic, and paleoecological interpretations of Pleistocene faunal response to climatic and other environmental changes.