FILLING THE GAPS: A COMPREHENSIVE UNDERSTANDING OF DIETS AND ECOSYSTEM INTERACTIONS WITHIN THE MODERN AND FOSSIL SMALL MAMMAL COMMUNITIES OF MEADE BASIN, KANSAS

The modern Great Plains ecosystem began shifting from a C₃ plant-dominated biome to a C₄ grassland in the Miocene. Stable isotope analysis (SIA) of a diverse community of local consumers, in this case small mammals, provides both a paleoenvironmental record of the shift from C₃ plant to C₄ grass biomass, and a paleoecological record of species interactions and community dynamics. The Meade Basin in southwestern Kansas contains a rich and fairly complete fossil record of a Great Plains small mammal community throughout the past 5 million years. SIA of fossil tooth enamel from Meade small mammals has revealed interesting dietary patterns among, and within, major lineages of rodents and lagomorphs. Yet, an incomplete understanding of ecosystem interactions in the modern small mammal community hinders our interpretation of these fossil isotopic datasets. Until now the majority of the modern Meade dataset was derived from 5 years of live trapping across a range of prairie microhabitats, and this sample is inherently biased towards small bodied and nocturnal species. The goal of this project is to fill taxonomic gaps in the modern sample, and provide a complete interpretation of current small mammal dietary ecology that is directly comparable to the fossil data. Our samples are derived from biologic (owl pellets, raptor nests, and prairie dog burrows), and anthropogenic (road kill) collections, which contain remains of previously under sampled taxa within the small mammal community. Preliminary results have already highlighted the importance of this work. For example, prairie dogs are the highest C₄ grass consumers in the modern community, and without them we would underestimate the use of C₄ resources by small mammals. As another example, rabbits have predominantly been mixed C₃-C₄ to strongly C₃ plant consumers throughout the past 5 million years, and that diet appears to be maintained today. Our complete isotopic dataset will consist of results for ~50 specimens, and will yield a comprehensive understanding of species and ecosystem interactions among small mammals in the Great Plains today.