The Association Between Dietary Niche Variation in Rodents and Climate Change Across the Paleocene-Eocene Thermal Maximum

Abstract

Mammalian teeth play a crucial role in food acquisition and breakdown and are therefore closely tied to dietary niche. This study reconstructed the diet of early Paleogene paramyid rodents across the Paleocene-Eocene Thermal Maximum (PETM) climatic event in an effort to understand the role of climate in mammalian dietary niche change. Dietary niches were quantified using three dental topographic measures: Dirichlet normal energy, relief index, and orientation patch count rotated. A Kruskal-Wallis test was conducted over eight time periods to determine if each of the dental topographic measures (i.e., diet) varied over time. Regression analysis of these measures with climatic variables was then used to evaluate the relationship of dietary niche with climate change. Results from the Kruskal-Wallis test indicated dietary niche variation over time (P=0.005) for the Dirichlet normal energy topographic measurement; however, regression analysis results did not indicate an association between dietary niche in these paramyid rodents and climate change across the time periods studied. While overall the results indicate that paramyid rodents likely experienced some dietary niche variation across the PETM, this study rejects the hypothesis that this variation is associated with the known climate change of this time. It is possible that the ability of paramyid rodents to utilize a large range of food resources resulted in a lack of competition for resources from mammalian immigrants and may have limited their need for significant dietary niche change in response to the PETM.