Undergraduate Honors Theses

The effects of climate change and megafaunal extinction on the body size and diet of the hispid pocket mouse (Chaetodipus hispidus) over the late Quaternary

Peyton WinterFollow

Date Thesis Awarded

4-2020

Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)

Department

Geology

Advisor

Rowan Lockwood

Committee Members

John Swaddle

Nicholas Balascio

Felisa Smith

Abstract

The end-Pleistocene extinction resulted in a significant loss of North American mammalian fauna—including all species larger than 600 kg. Considerable research has focused on the large-bodied victims of this extinction, but to date, little is known about the impact on the surviving small mammal species.

Here, we characterize the influence of climate and biodiversity loss over the late Quaternary on the hispid pocket mouse (Chaetodipus hispidus) from Hall’s Cave, Texas. Specifically, using a well dated fossil record, we analyzed the changes in the population body size and diet of C. hispidus across the last 16,000 years. In total upwards of 400 specimens were examined with approximately 45 specimens (30 for body size and 15 for diet) from each of 12 time intervals, each representing ~1.3 ka. Body size was estimated from the lower tooth row length and diet was assessed using isotopic niche estimated from carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes of bone collagen from fossil mandibles. We found that average body mass decreased significantly across the pre- and post-extinction time interval as well as across individual time bins. Isotopic analysis revealed little to no change in δ¹³C values but a significant decrease in δ¹⁵N values. Decreasing body size was shown to be statistically significantly correlated with an increase in temperature and a decrease in precipitation and species richness. Diet appears to have no significant correlation with body size, with decreasing δ¹⁵N values possibly linked to a baseline shift in nitrogen within the ecosystem itself. These results suggest C. hispidus is strongly impacted by variations in climate with changes in community structure playing a secondary role; however, whether these relationships are direct or indirect remains unclear.

Recommended Citation

Winter, Peyton, "The effects of climate change and megafaunal extinction on the body size and diet of the hispid pocket mouse (Chaetodipus hispidus) over the late Quaternary" (2020). Undergraduate Honors Theses. William & Mary. Paper 1541.
https://scholarworks.wm.edu/honorstheses/1541