Abstract
The catastrophic loss of large‐bodied mammals during the terminal Pleistocene likely led to cascading effects within communities. While the extinction of the top consumers probably expanded the resources available to survivors of all body sizes, little work has focused on the responses of the smallest mammals. Here, we use a detailed fossil record from the southwestern United States to examine the response of the hispid cotton rat Sigmodon hispidus to biodiversity loss and climatic change over the late Quaternary. In particular, we focus on changes in diet and body size. We characterize diet through carbon (δ13C) and nitrogen (δ15N) isotope analysis of bone collagen in fossil jaws and body size through measurement of fossil teeth; the abundance of material allows us to examine population level responses at millennial scale for the past 16 ka. Sigmodon was not present at the cave during the full glacial, first appearing at ~16 ka after ice sheets were in retreat. It remained relatively rare until ~12 ka when warming temperatures allowed it to expand its species range northward. We find variation in both diet and body size of Sigmodon hispidus over time: the average body size of the population varied by ~20% (90–110 g) and mean δ13C and δ15N values ranged between −13.5 to −16.5‰ and 5.5 to 7.4‰ respectively. A state–space model suggested changes in mass were influenced by diet, maximum temperature and community structure, while the modest changes in diet were most influenced by community structure. Sigmodon maintained a fairly similar dietary niche over time despite contemporaneous changes in climate and herbivore community composition that followed the megafauna extinction. Broadly, our results suggest that small mammals may be as sensitive to shifts in local biotic interactions within their ecosystem as they are to changes in climate and large‐scale biodiversity loss.
Highlights
Large-bodied mammals play a critical role within communities and ecosystems
The substantial amount of fossil material, and the robust and detailed age model provide a unique opportunity to reconstruct the ecology of Sigmodon hispidus in a period marked by intense shifts in both biodiversity and climate
Our results suggest that S. hispidus is being influenced by both climatic and community variables over time, likely through a combination of direct and indirect effects, but that the combination of these effects is not driving a strong shift in body size and/or diet
Summary
Large-bodied mammals play a critical role within communities and ecosystems. Either directly or indirectly, they influence soil and vegetation structure and composition, nutrient cycling and other biogeochemical processes, and especially, the distribution. Selection for a larger (or smaller) body size changes how animals interact with and/or are impacted by their ecosystem (Damuth 1981, Peters 1983, Calder 1984) This coupling of climatic change at the late Quaternary with the terminal Pleistocene megafauna extinction likely led to substantial ecosystem alterations for surviving mammals. The substantial amount of fossil material, and the robust and detailed age model provide a unique opportunity to reconstruct the ecology (diet and body size) of Sigmodon hispidus in a period marked by intense shifts in both biodiversity and climate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
