Distribution and paleobiology of hibernation in fossil ground-dwelling squirrels from the Meade Basin, SW Kansas, USA
Hibernation is an adaptation to seasonality in resource availability, typically associated with sharp seasonal decrease in temperatures during winters (e.g., Williams et al. 2014). Previous work in my lab documented the biology of one modern hibernator, the thirteen-lined ground squirrel (Kisser and Goodwin 2012); and demonstrated that hibernation is reflected in the growth structure of evergrowing incisor teeth, both modern and fossil (Goodwin and Gonzalez 2001; Goodwin et al. 2005; Goodwin and Ryckman 2006), as well as in stable isotope profiles of these teeth (unpublished data). We demonstrated that hibernation occurred as early as the middle Pleistocene (Ice Age).
We propose to investigate distribution of hibernation in a rich fossil sequence from the Meade Basin, SW Kansas, which spans the late Miocene through Pleistocene. We propose, first, to document whether hibernation is recorded in fossil squirrel incisors from this sequence, with potential to push the record back to the late Miocene. Second, we propose to test two hypotheses about controls on hibernation (if observed) in time: a) that presence/absence of hibernation is phylogenetically controlled (that is, some species hibernate and others not, irrespective of environment); and b) that onset of hibernation in the region is associated with annual temperatures that cool past a critical threshold, initiating short growing seasons to which hibernation is adaptive. We will develop a protocol for identifying incisors to family, and will apply protocols developed in previous studies to recognize the hibernation mark. The project will be done with an Honors student, Mr. Randy Sanchez.