2 - Biogeographical Rules and Bone Density; A Long Bone Assessment of the Eastern Gray Squirrel (Sciurus Carolinensis)

Poster Board Number: 2
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Abstract Body : Data obtained from bone analyses have reinforced hypotheses in biology for centuries. These studies focus on diverse species to understand variability in bone morphology. To understand how bone responds to environmental factors, numerous studies have examined species that are abundant in nature, with diverse ecological niches, and short life spans such as gray squirrels (Sciurus carolinensis). They are one of the most well studied organisms in North America, but little is known about their bone plasticity. The goal of this study is to examine the effect of urbanization and latitude on bone morphology specifically, on limb length and bone density among gray squirrels endemic to the eastern United States. First, we hypothesize that gray squirrels occupying the lower latitudes will have longer limbs than those in the higher latitudes following Allen’s rule. Secondly, that gray squirrels living in urban areas (inferred by population density) with great access to human food waste will have lower bone density than those in rural and more “natural” niches. We measured femoral and humeral lengths, and midshaft cortical bone density of gray squirrel specimens (n=28). We used electronic calipers to measure lengths and peripheral quantitative computed tomography (pQCT) to quantify bone density. Preliminary results show a strong correlation between bone length and latitude (n=0.7) in both the femur and humerus rather than an inverse correlation per Allen’s rule. Bone density data did not reveal a positive correlation with urbanization in either bone. Whereas additional data collection is needed, this study advances our understanding of how changing climate, human development and expansion influence the bone morphology of wildlife.